Cardiovascular Research 52 (2001) 361–371
www.elsevier.com / locate / cardiores
Review
Longchain n23 polyunsaturated fatty acids and blood vessel function
Mahinda Y. Abeywardena*, Richard J. Head
CSIRO Health Sciences and Nutrition, Kintore Avenue, P.O. Box 10041, Adelaide BC, SA 5000, Australia
Received 26 April 2001; accepted 3 July 2001
Abstract
The cardiovascular health benefits of longchain n23 polyunsaturated fatty acids (PUFAs) have been reported to exert at several
different cellular control mechanisms. These include, effects on lipoprotein metabolism, haemostatic function, platelet / vessel wall
interactions, anti-arrhythmic actions and also inhibition of proliferation of smooth muscle cells and therefore growth of the atherosclerotic
plaque. Fish oil feeding has also been found to result in moderate reductions in blood pressure and to modify vascular neuroeffector
mechanisms. The majority of such cardiovascular benefits of n23 PUFAs are likely to be mediated in the vascular wall and at the
vascular endothelium level, since this monolayer of cells plays a central role in the regulation and maintenance of cardiovascular
homeostasis and function. While these processes include endothelium-derived vasorelaxant and vasoconstrictor compounds, the vascular
endothelium also plays host to many receptors, binding proteins, transporters and signalling mechanisms. Accordingly, endothelial
dysfunction, which underlies many cardiovascular disease conditions, can trigger acute vascular events including vasospasm, thrombosis
or restenosis leading to ischaemia. The longchain n23 PUFAs have been reported to possess several properties that may positively
influence vascular function. These include favourable mediator profiles (nitric oxide, eicosanoids) that influence vascular reactivity,
change in vascular tone via actions on selective ion channels, and maintenance of vascular integrity. In addition to direct effects on
contractility, n23 PUFAs may affect vascular function, and the process of atherogenesis, via inhibition of vascular smooth muscle cell
proliferation at the gene expression level, and by modifying expression of inflammatory cytokinesis and adhesion molecules. Collectively,
these properties are consistent with pleiotropic actions of longchain n23 PUFAs, and may explain the beneficial cardiovascular protection
of this family of fatty acids that have been clearly evident through epidemiological data as well from more recent large-scale clinical
trials.  2001 Elsevier Science B.V. All rights reserved.
Keywords: Endothelial function; Nitric oxide; Prostaglandins; Vasoconstriction / dilation
1. Introduction
The benefits of high consumption of n23 polyunsaturated fatty acids (n23 PUFAs) on cardiovascular disease
mortality was first noted over two decades ago [1]. Now it
is well recognised that longchain PUFAs of marine origin
possess a multitude of actions that combat the pathogenesis
of coronary heart disease (CHD; [2–4]). Although dietary
intervention with fish oils failed to reduce incidence of
restenosis following coronary angioplasty, and conflicting
data exists for regression of atherosclerosis [3,5], signifi*Corresponding author. Tel.: 161-8-8303-8889; fax: 161-8-83038899.
E-mail address: [email protected] (M.Y. Abeywardena).
cant benefits of n23 PUFAs (eicosapentaenoic acid, 20:5
n23, EPA; docosahexaenoic acid, 22:6 n23, DHA) from
fish oil have been observed at several different stages of
CHD process. These include effects on lipoprotein metabolism, platelet / vessel wall interactions (thrombosis), cardiac
arrhythmia, and ischaemic damage to heart muscle, proliferation of smooth muscle and growth of atherosclerotic
plaque.
The finding that n23 PUFAs from fish oil can produce
moderate reductions in blood pressure in experimental
models of hypertension and in humans has focussed
attention on a potential role of n23 PUFAs in modulating
vascular contraction and vasodilatation. This review high-
Time for primary review 19 days.
0008-6363 / 01 / $ – see front matter  2001 Elsevier Science B.V. All rights reserved.
PII: S0008-6363( 01 )00406-0
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M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
lights some of the key observations that helped characterise the role of n23 PUFAs on acute physiological responses in blood vessels as well as their role in modulating
vascular cell to cell interactions that impinge on thrombosis formation and innervated vascular smooth muscle
cell (VSMC) proliferation.
2. The vascular endothelium
The endothelium plays a key role in vascular function
and attempts to maintain normal homeostasis via the
production of a range of biochemical mediators (Fig. 1).
The endothelium is also host to many receptors, binding
proteins, transporter and signalling mechanisms involved
in the regulation of cellular processes including cell
growth, programmed cell death (apoptosis) and cell migration. Most biochemical mediators produced by the endothelium are likely to exert modulatory actions on one or
more of these processes as well as to influence actions of
other mediators [6,7]. Locally generated vasoactive agents
of endothelial cell origin include angiotensin II (converted
from angiotensin I by the angiotensin converting enzyme
(ACE) in endothelial cells), nitric oxide (NO), endothelium
derived hyperpolarizing factor (EDHF), eicosanoids and
polypeptide molecules such as endothelin. In certain
disease states endothelium may also produce increased
level of free radicals and promote abnormal contraction of
blood vessels.
Endothelial dysfunction therefore potentially reflects an
imbalance between the vasoconstriction and vasodilator
compounds and is associated with several cardiovascular
risk factors such as hypercholesterolaemia, hypertension,
diabetes and smoking. Such abnormalities in the endothelium, which underlie many cardiovascular disease conditions, may trigger acute vascular events including vasospasm, thrombosis or restenosis resulting in myocardial
Fig. 1. Vasoactive compounds released by the endothelium. A range of
biochemical mediators are produced by the vascular endothelium and
involved in the maintenance of normal homeostasis. NO, nitric oxide;
PGI 2 , prostacyclin; EDHF, endothelium derived hyperpolarising factor;
A-II, angiotensin II; ET, endothelin; TxA 2 / PGH 2 , thromboxaneA 2 / prostaglandin H 2 ; O 2? , superoxide anion.
Fig. 2. Endothelial dysfunction in cardio and cerebro-vascular disease.
Abnormalities in endothelial function can trigger acute vascular events
and precipitate ischaemic attacks.
ischaemia and sudden death from ventricular arrhythmias
(Fig. 2).
It is conceivable that anti-thrombotic as well as antiatherogenic actions of n23 PUFA are at least in part
mediated at the vascular endothelial cell level since this
monolayer of cells not only influences platelet / vessel wall
interactions but also cell proliferation, cell death and
structural alterations of blood vessels known as vascular
remodelling.
The multiple modes of action of n23 PUFA may
include an influence on blood vessels since at least two
physiologically important biochemical mechanisms operating mainly in the vascular endothelium have been shown
to be positively modulated by fish oil fatty acids. The first
is the ability to modify eicosanoid biosynthesis [2], and the
other is an increased endogenous nitric oxide (NO)
production following supplementation with fish oil [8].
Both processes can influence vascular reactivity and likely
to form the basis for the reported improvements in
endothelial function and arterial elasticity observed with
n23 PUFAs [9,10]. Evidence also indicates that n23
PUFAs may influence vascular tone by exerting action on
selective ion channels [11,12] and maintain vascular
integrity by influencing soluble markers of endothelial
haemostatic activity [13]. Collectively, these findings
provide the basis for observations in experimental animal
models and human subjects which confirmed moderate
reductions in blood pressure [2–4,14,15] with n23 PUFAs
suggesting altered vascular neuroeffector responses.
2.1. Neuroeffector and vascular responses
Vascular neuroeffector mechanisms refer to the physiological processes underpinning responses generated by
either stimulation of the sympathetic nerves innervating the
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
vasculature or direct stimulation of VSMC in the region of
the sympathetic nerve-rich adventitia. Potential mechanisms of blood pressure lowering by n23 PUFAs have
been extensively studied in experimental animal models of
hypertension particularly the spontaneously hypertensive
rat (SHR) with the Wistar–Kyoto rat (WKY) serving as its
control. Dietary fish oil administration reduced the enhanced vascular contractility in the hypertensive animals
[14–18] and in humans [4,8,10]. In agreement with
observations in animals [18], findings in humans also
demonstrates potentially a greater role for DHA rather than
EPA in favourably modifying vascular reactivity and
lowering blood pressure [19,20].
A variety of mechanisms have been advanced and
explored to seek a molecular basis for the antihypertensive
and neurovascular modulatory role of dietary fish oils.
Included within these approaches has been a determination
of whether vasodilator / vasoconstrictor mechanisms based
upon eicosanoid metabolism (prostaglandins and thromboxanes) and nitric oxide (NO) production plays a role in
the modulating actions of dietary fish oils. While, there
appears to be no major involvement of vasodilatory
prostaglandins [15], thromboxane-A 2 (TxA 2 ) production is
elevated in the SHR and modified favourably with fish oils
[15–18,21].
It is established that activation of NO production in the
vascular endothelium induces vasodilatation. In the SHR,
NO mediated relaxation in the aorta is impaired and
restored with fish oil administration [17]. This could be
due to a suppression of vasoconstriction by NO in the
normotensive state and an absence of a similar influence in
the SHR. However, it would seem unlikely that the
modulation of contractile responses by fish oil treatment in
the SHR is solely attributable to a primary role of n23
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PUFAs in restoring endothelium dependent relaxation. For
instance, endothelium independent relaxant effects of EPA
and DHA have been reported in animal and human studies
[20,22,23]. While the basic mechanism is unclear in the
human setting, vasorelaxation in the WKY and SHR
induced by EPA and DHA are thought to involve prostanoid mediated activation of K 1 -ATP channels, and
mobilisation of intracellular Ca 21 in VSMC via L-type
(DHA) and non L-type (EPA) Ca 21 channels [22,23].
Therefore, it appears that fish oils may influence receptor function, transduction processes and membrane ion
channels in the vasculature. There is growing evidence
(discussed later) supporting a role of fish oils in altering
ion transport to promote a hyperpolarising action. Further
focus should also be directed toward understanding the
potential influence of specific n23 PUFAs on vascular
remodelling and favourably influencing vascular neuroeffector mechanisms (Fig. 3). In this context it should
noted that EPA inhibits VSMC proliferation [24,25], and
DHA has been reported to trigger VSMC apoptosis implicating a role in vascular remodelling [25,26].
3. Biochemical mediators
3.1. Eicosanoids
EPA and DHA can act as alternative substrates, for both
cyclooxygenase (COX) and lipoxygenase (LOX) enzyme
complexes giving rise to 3-series prostaglandins and
thromboxanes, and 5-series leukotrienes respectively (Fig.
4). Although these metabolites bear considerable structural
resemblances to those produced by the preferred substrate
Fig. 3. Beneficial modulation of vascular abnormalities in hypertension by longchain n23 PUFAs. Studies with fish oils in experimental animal models
and human subjects demonstrate n23 PUFAs to exert a wide range of protective actions on the vascular structure and function.
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M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
Fig. 4. Major eicosanoid metabolites derived from n23 and n26 polyunsaturated fatty acid substrates. Different families of eicosanoids with varied
biological potencies are produced by n23 PUFAs. COX, cyclooxygenase; LOX, lipoxygenase; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid;
AA, arachidonic acid; LT, leukotrienes; PG, prostaglandin; Tx, thromboxane.
for eicosanoid biosynthesis — n26 polyunsaturated arachidonic acid (AA, 20:4 n26) — the overall cardiovascular
benefits exerted by products derived from n23 PUFAs are
more favourable due to differences in biological activities
(Fig. 4; [2,27–29]).
The observed anti-thrombotic actions of fish oil PUFAs
are generally explained by the inhibition of platelet TxA 2
and parallel changes in the clotting mechanisms. Significant reduction in TxA 2 production following longchain
n23 PUFAs has been observed both in vitro and in vivo
studies both in experimental animal models and in human
subjects [2,28]. In vitro estimation of prostacyclins —
PGI 2 1PGI 3 — also shows a reduction after n23 PUFA
feeding, albeit smaller in magnitude than TxA 2 . In contrast, in vivo studies exhibited either no change or even an
increased generation of PGI 2 following n23 PUFAs
[27,29,30] providing evidence for a possible differential
modulation of thromboxane and prostacyclin production by
the n23 PUFAs [31]. Differences between in vitro and in
vivo production, as measured by the excretion of urinary
metabolites, have also been reported for E and F series
prostaglandins [32]. The vascular endothelium is the main
source of anti-aggregatory and vasodilatory prostacyclins,
therefore preservation of beneficial prostacyclins at the
expense of thromboxanes could form a key mechanism for
the reported benefits of n23 PUFA on vascular function.
This specific inhibitory action n-PUFA on TxA 2 synthesis is not explained by the changes in the availability of
precursor fatty acids alone and may perhaps be exerted at
the biosynthetic enzyme level [31]. In addition, DHA and
EPA have been shown to act as antagonists at the TxA 2 /
PGH 2 receptor in human platelets [33]. In the latter study,
DHA was found to be more potent than EPA in blocking
the activation of platelets induced by the stable TxA 2
mimetic U46619. However, DHA was the only PUFA to
show competitive antagonism at the TxA 2 / PGH 2 receptor
in rat aorta [34].
Further evidence in support of increased PGI 2 production was reported by Saito et al. [35] who observed
enhanced synthesis in cultured rat VSMC enriched with a
triglycerol emulsified form of EPA. Interestingly, DHA-TG
was without effect. Activation of COX by EPA via the
generation of low lipid peroxide level has been put forward
as a potential mechanism although the failure of DHA to
similarly activate the COX enzyme complex remains
unclear. In contrast, Achard et al. [36] found in bovine
aortic endothelial cells that both EPA and DHA reduce
PGH synthase-1 expression, perhaps at the transcriptional
level, thereby inhibiting the synthesis of PGI 2 . n23
PUFAs however, did not inhibit the endothelial cell PGI 2
synthase. Both EPA and DHA caused approximately a
50% inhibition in PGI 2 production in response to a range
of exogenous stimulants such as bradykinin, calcium
ionophore and AA.
Docosapentaenoic acid (DPA; 22:5 n23) has also been
shown to be inhibitory in the system but the effect may be
attributed to retroconversion of DPA to EPA [37]. Whether
this is a reflection of what occurs in vivo is an open
question since as indicated earlier, several studies have
reported differences between in vitro and in vivo generation of beneficial prostacyclins (PGI 2 1PGI 3 ) by n23
PUFAs. Further studies exploring the effects of n23
PUFAs on platelet thromboxane biosynthetic enzymes,
both at the biochemical and at the gene expression level,
would be needed to comprehensively define the modulation, including any preferential production of prostacyclins
by n23 PUFAs [31,38] in maintaining an anti-thrombotic
state.
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
3.2. Nitric oxide
It could be argued that recent observations of increased
urinary excretion of NO metabolites in humans after fish
oil supplementation [8] may be the primary mechanism
responsible for the anti-thrombotic effect of n23 PUFAs
in that enhanced endogenous NO may offset vasoconstrictor influences in general as well as any reductions in
vasodilatory influence of PGI 2 by these polyenoic fatty
acids. Nevertheless, it is worth noting that no increase in
endogenous NO production was seen with EPA and that
DHA appears to be the active component in mediating this
effect [8]. This latter observation however, is possibly at
odds with an anti-thrombotic action based on a differential
modulation of eicosanoids since both EPA and DHA have
been shown to be effective in achieving a favourable
prostacyclin / thromboxane ratio. Furthermore, preparations
enriched in EPA as well as DHA have been shown to
either maintain or even increase the generation of prostacyclins in experimental animals and in humans
[29,30,38].
The observation that EPA was ineffective in increasing
NO is an intriguing one since several studies reported that
DHA may play a more prominent role than EPA in
conferring protection against several cardiovascular disease
indices. These include lipids and lipoproteins, hypertension, cardiac arrhythmia, heart rate, vascular reactivity and
hypertension induced renal damage [4,18]. It is possible
that a prominent role of DHA when contrasted to EPA in
providing this vasoprotection may perhaps be related to a
differential influence on endothelial cell NO [8]. However,
in vitro treatment of rat aortic rings with either EPA or
DHA augmented the endothelium dependent vasorelaxation to a similar extent due to an enhanced release of
EDRF and vasodilator prostaglandins [39]. Furthermore,
Omura et al. [40] observed EPA, but not DPA or DHA
stimulated NO production and induced endothelium-dependant relaxation in bovine coronary arteries precontracted with thromboxane mimetic U46619. In contrast,
both EPA and DHA caused significant inhibition of
vasoconstriction in the isolated perfused rabbit ear induced
by E 2 and F 2 isoprostanes and U46619 [41]. More studies
are needed in relation to the mechanisms of vasorelaxation
induced by n23 PUFAs since both EPA and DHA have
also been reported to antagonise TxA 2 / PGH 2 receptors
[33,34] as well as to induce relaxation via endothelium
independent mechanisms [20,22,23].
In addition to enhancing vasodilatory influence, n23
PUFAs may inhibit the release of vasoconstrictor agents.
Similarly to the effects on vasoconstrictor eicosanoids
[2,28], EPA has been found to cause a dose dependent
inhibition of endothelin (ET-1) production in bovine
mesangial cells [42].
3.3. Nitric oxide, eicosanoids and isoprostanes
There is a potential interplay between NO and
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eicosanoids [43] and the role of n23 PUFAs in modulating vascular function should be measured against this
interaction. For example, it was demonstrated in hypertensive rats that inhibition of endothelial cell NO production
unmasked a vasoconstrictor response that was sensitive to
COX inhibitors as well as following the blockade of
TxA 2 / PGH 2 receptors [44,45]. However, this abnormal
TxA 2 -like constrictor response is mainly mediated via
prostaglandin endoperoxides (PGG 2 / PGH 2 ) intermediates
as inhibitors of TxA 2 synthetase was without effect [45].
Furthermore, it was observed that pre-feeding of hypertensive rats with purified DHA attenuated this response whilst
dietary EPA failed to alter this abnormality [18]. It appears
that this differential action of DHA is mediated via two
distinct mechanisms (Fig. 5) — via an inhibitory effect at
the TxA 2 synthetase level [31] and by antagonism at the
vascular TxA 2 / PGH 2 receptor [34]. This receptor antagonism was only observed for DHA and not shared by other
n23 PUFAs and is in agreement with observations following dietary administration of fish oil [18,34].
It is likely vascular relaxation promoted by fish oils
[9,10,14,16] is exerted mainly at the biochemical mediator
level including the inhibition of TxA 2 -like constrictor
response [18] whilst preferentially preserving or increasing
the prostacyclins [27–31], or by directly modulating NO
[8,40,46,47]. Current knowledge also suggests that isoprostanes — prostaglandin-like compounds formed nonenzymically from free radical mediated oxidation of
membrane lipids [48,49] — as potent modulators of
vascular contractility [48–50]. Studies also indicate the
production of isoprostanes via COX and NO pathways [51]
and thus assign a link between NO, prostanoids, free
radicals and isoprostanes for the regulation of vascular
tone [43]. The production and / or physiological effects of
isoprostanes that may result from longchain n23 PUFAs
are yet to be established due mainly to analytical limitations in characterising the different yet structurally closely
resembling families of different isoprostanes and prostaglandins.
Another possibility is that although longchain n23
polyenoic fatty acids have generally been regarded as
susceptible to oxidation due to the presence of number of
double bonds, it is equally likely that in situ these PUFAs
may act as a sink and / or scavengers to remove specific
free radicals. Acute additions of n23 PUFAs to human
neutrophils have been reported to decrease superoxide
anion generation primarily via a prostaglandin dependant
pathway [52], and fish oil supplementation has been shown
to attenuate free radical generation following coronary
occlusion and reperfusion in rabbits [53]. In vivo assessment of oxidant stress in humans — as quantified by
urinary F2 isoprostanes — have confirmed these earlier
reports and also demonstrated both EPA and DHA to
equally reduce the endogenous free radical status [54].
Therefore, n23 PUFAs in addition to exerting direct
actions at the substrate, enzyme and receptor levels may
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M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
Fig. 5. Differential modulation of PGI 2 and TxA 2 by longchain n23 PUFAs. Fish oil fatty acids may preferentially reduce the effects of vasoconstrictor
mediators (e.g. thromoboxane-A2, isoprostanes) via distinct mechanisms (see text).
also be to modulate key mediator pathways in the vasculature including COX, NO and isoprostane production, all of
which are dependant on the endogenous free radical status
[48,49,55,56]. Collectively these mechanisms argue for the
role of n23 PUFAs in mediating a shift from vasoconstriction to vasodilatation (Figs. 4 and 5).
4. Vascular membrane ion channels
A role of n23 PUFAs is modulating ion channels in cell
membranes has arisen from studies on excitable cardiac
muscle cells. The n23 PUFAs prevent abnormal beating in
rat cardiomyocytes exposed to several arrhythmogenic
stimulants [57]. It has been proposed that the n23 PUFAs
exert this influence by influencing Ca 21 availability by
inhibition of voltage dependent L-type Ca 21 channels and
voltage dependent Na 1 currents [58–60]. A major focus of
the role of n23 PUFAs and cardiac muscle cell excitability has been directed toward ischaemia induced arrhythmias
as these fatty acids prevent the development of ventricular
fibrillation (VF) associated with coronary artery ligation in
several animal models [61–64]. Work using isolated mammalian cell lines [65], myocytes [57–60] and studies on
heart rate variability (HRV) in humans [66,67] have
allowed a better understanding of anti-arrhythmic actions
of n23 PUFAs. HRV which is a measure of cardiac
autonomic tone, indicates that modulation of electrophysiological properties of the myocardium by n23 PUFAs as
the most likely mechanism for their anti-arrhythmic actions. n23 PUFAs have been shown to increase HRV,
which is reflected as a higher VF threshold thus reducing
the vulnerability to arrhythmia [66,67]. In view of the
importance of ion channels in vascular smooth muscle
function it is not surprising that attention has been drawn
to an interaction of n23 PUFAs and ion channels and
vascular function.
Another potential mechanism by which n23 PUFAs
may regulate vascular tone was reported by Asano et al.
[11]. Using cultured rat VSMC and voltage clamp technique, these investigators found that n23 PUFAs — EPA,
DPA and DHA, inhibit the receptor mediated non-selective
cation current and in addition, activate a K 1 current in a
concentration dependent manner. Although the ability of
n23 PUFAs to block the Na 1 channel in rat ventricular
myocytes has been reported previously [59,60], these
findings on the effectiveness of n23 PUFAs to activate K 1
channels indicate that this hyperpolarizing action may also
contribute to the vasorelaxant actions of fish oil fatty acids.
The effects of long-term treatment to permit incorporation of n23 PUFAs within cellular pools, as compared to
acute challenge, on electrophysiological properties of
VSMC was also recently reported by [12]. Treatment of rat
A7r5 VSMC cells with EPA for 7 days was associated with
a partial inhibition of resting intracellular calcium concentration [Ca 21 ] i and agonist induced rise in [Ca 21 ] i . In
addition, EPA treatment tended to hyperpolarize resting
membrane potential through an increase in outward currents generated via the activation of K 1 channel and
Na 1 / K 1 pump. These findings are of considerable interest
since the hyperpolarizing effects of n23 PUFAs following
long-term treatment may suppress or inactivate voltage
dependent Ca 21 channels resulting in a lower [Ca 21 ] i and
inhibit the agonist induced increases in [Ca 21 ] i in excitable
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
cells providing an electrophysiological basis for the reported anti-arrhythmic, vasorelaxant as well as antiatherogenic actions of n23 PUFAs. In support of the this
latter speculation for anti-atherogenic actions, the authors
observed that parallel to the reduction in membrane
potential and [Ca 21 ] i , EPA pre-treatment also inhibited the
PDGF induced migration of VSMC.
There is accumulating evidence to suggest that n23
PUFAs have an ability to act at the cellular ion channel
levels to alter the electrophysiology of excitable cells and
therefore to directly influence physiological parameters
including cardiac rhythm and vascular tone.
5. Growth and proliferation of vascular cells
5.1. Cell proliferation
In addition to their direct influence on vascular contractility and on more acute cellular events, n23 PUFAs may
also influence vascular function and the process of
atherogenesis by influencing the growth and proliferation
of VSMC [24–26,68]. Interestingly, the potency for this
anti-proliferative action has been reported to be greater for
EPA than DHA [69], which differs from the observations
for cardiovascular protection where DHA appears to play a
more prominent role [8,18–20].
The inhibition of VSMC proliferation by EPA is
achieved at various steps of the signal transduction pathway for growth factors. For example, EPA has been shown
to prevent the binding of PDGF to its surface receptor [24],
to suppress Protein Kinase C activation and mRNA
expression of the early growth gene in the nucleus, c-fos,
by inhibiting c-fos transcription. In addition, cyclins and
their catalytic subunits; cyclin-dependent kinases, which
control the progression of the cell cycle via DNA synthesis, have also been reported to be inhibited by the
longchain n23 PUFAs, EPA and DHA [69]. EPA also
been reported to suppress the transforming growth factor-b
and inhibit the exaggerated growth of VSMC of SHR [25].
Taken together, it appears that these longchain polyenoics
may inhibit the proliferation of VSMC by more than one
mechanism - modulation of various steps of growth signals
as well by inhibiting DNA synthesis.
5.2. Adhesion molecules
The adhesion of circulating leukocytes to vascular
endothelium and subsequent recruitment and infiltration of
monocytes into the vascular wall is a major event in the
biological events underpinning atherogenesis and inflammation. This complex series of events are primarily
regulated by the expression of a range of adhesion
molecules on vascular endothelial cells aided by the
release of various chemo-attractant factors. Whilst a normal healthy endothelium tends to repel the adhesion of
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leukocytes, an activated endothelium may promote adhesion processes. A range of compounds of different origin
including, oxidised low-density lipoproteins, lipopolysaccharides and inflammatory cytokines (e.g. interleukins,
tumour necrosis factor alpha) have been found to cause
‘endothelial activation’. Significant modulation of endothelial adhesion molecules by n23 PUFAs has also been
reported [70] and reviewed [71]. The expression of Vascular Cell Adhesion Molecule-1 (VCAM-1) has been reported to be reduced by DHA. In addition, DHA exerted a
time and dose dependent reduction in the expression of
endothelial cell adhesion molecule-1 (ELAM-1 / E-selectin), Intracellular Adhesion Molecule-1 (ICAM-1), interleukins (IL-6 and IL-8) after challenging with various
stimuli and the extent of reduction paralleled the incorporation of DHA into cellular phospholipids. Further to the
reduced expression of adhesion molecules and leukocyte
recruitment agents, DHA was found to reduce the adhesion
of human monocytes and monocratic U937 cells to activated endothelial cells [71–73]. In human umbilical vein
endothelial cells stimulated with inflammatory cytokine
interleukin 1-beta (IL-1b), the expression of ICAM-1,
VCAM-1 and E-selectin mRNA levels was reduced by
EPA and DHA.
It is noteworthy that these modulatory effects appear to
be totally independent of DHA metabolism to cyclooxygenase products [71,73]. Similarly, only DHA not EPA
reduced the cytokine stimulated VCAM-1 expression and
resulted in a greater reduction in pro-inflammatory cytokine production. Adhesion of human lymphocytes to
endothelial cells was reported to be inhibited by either the
addition or pre-treatment with n23 PUFAs [72]. Several
studies have found DHA to possess greater potency in
comparison to EPA although the two PUFAs in association
may act synergistically [73,74].
5.3. Fatty acid structure
Structural requirements for unsaturated fatty acids in
relation to endothelial activation by pro-inflammatory
cytokines have recently been identified [71,75]. In summary, the expression of VCAM-1 in endothelial cells
activated with pro-inflammatory cytokines such as IL-1,
TNF or bacterial lipopolysaccharide, was found to be
directly related to the presence (or absence) of double
bonds in the fatty acid molecule rather than the type of
unsaturation (i.e. n23 vs. n26). These investigators also
concluded that a double bond is the minimum necessary
and sufficient requirement for fatty acid inhibition of
endothelial activation. Therefore, the highest potency was
seen with DHA which accommodates the highest number
(six) of double bonds whilst both DPA and EPA, although
differing in chain length, have the same number of double
bonds and yielded identical results. Similarly, inhibition by
AA was lower than EPA and the fatty acids with the same
chain length but with variable number as well as the type
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M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
of unsaturation of double bonds — oleic (18:1 n29),
elaidic (18:1 n29 trans isomer of oleic acid), linoleic
(18:2 n26), a-linolenic (a18:3 n23) and g-linolenic
(g18:3 n26) — all yielded inhibitions that were reflective
of the number of double bonds rather than the type of
unsaturation. Whilst monounsaturated palmitoleic acid
(16:1) was similar to oleic and elaidic acids, saturated fatty
acids palmitic (16:0) or stearic (18:0), failed to provide
any protection. Furthermore, the protective effects of
unsaturated fatty acids required the incorporation of the
fatty acid in question to specific fatty acid pools within the
endothelial cell. This is in contrast to an apparent lack of
requirement for incorporation in studies reported for the
inhibition of ion channels following the acute addition
n23 PUFAs as in the case for anti-arrhythmic activity in
cultured myocytes [58–60] or opening of K 1 channels in
rat VSMC cells [11].
These findings may imply that altered fatty acid composition is a pre-requisite for the modulation of gene
expression for adhesion molecules. However, it is also
clear that this effect is not mediated via a general alteration
in the physico-chemical properties or ‘fluidity’ of the
membrane, since fatty acids with either cis or trans double
bonds resulted in same inhibitory potencies despite the
wide differences in physical properties that are known to
exist between these two configurations [76]. It was concluded that n23 PUFA will have the largest beneficial
effect among unsaturates for a given chain length since
they accommodate a greater number of double bonds and
in addition serves as poor substrates for eicosanoids
biosynthesis [75].
In vascular endothelial cells, DHA has been found to
increase membrane fluidity more than EPA [77]. In cardiomyocytes, however, any alterations in packing of
membrane phospholipids by n23 PUFAs are found not to
be responsible for their anti-arrhythmic properties [78].
Such observations may add a further dimension to the
currently held view regarding the potential for increased
lipid peroxidation in highly polyunsaturated fatty acids.
The findings could suggest that the higher the number of
double bonds in the fatty acid molecules, the greater the
protection against endothelial activation, which can trigger
inflammation and the process of atherogenesis. It appears
that increased number of double bonds in the fatty acid
molecule may be effective in conferring a higher protection. Conceivably this could be achieved by the PUFAs
from by acting as a sink for the damaging effects of
reactive free radicals.
Collectively, these data suggests that n23 PUFAs have
the ability to modulate certain key biologically active
proteins involved in the pathogenesis of atherosclerosis
through gene expression as well as at DNA and protein
synthesis levels in a manner independent of their modulatory effects on eicosanoid metabolism. Similarly, further
studies on structure–activity relationships of the n23
PUFAs induced changes in electrophysiology with re-
sultant effects on intracellular distribution of ions may in a
similar fashion further our understanding with regard to the
specific anti-arrhythmic and vasorelaxant actions of n23
PUFAs.
6. Summary
When reviewing the influence of n23 PUFAs on
cardiovascular function it is apparent that these fatty acids
influence a wide range of biochemical and physiological
functions. This is not surprising in view of the pivotal role
fatty acids play in membrane function and integrity as well
as their related role in the synthesis of biologically active
lipid mediators. However what does emerge are two
distinct actions which may provide insights into the precise
nature of the interaction of PUFAs in the cardiovascular
system. Firstly the n23 PUFAs exert beneficial effects on
several different cardiovascular risk factors including
favourable influences on plasma triglycerides, blood pressure, platelet and leukocyte function and coagulation and
fibrinolysis processes [2–5,13]. In addition, the n23
PUFAs provide protection during the acute events associated with, for example, myocardial ischaemia [61–64]. In
blood vessels it emerges that n23 PUFAs decrease either
the expression or activity of the processes that favour
platelet aggregation and induction of abnormal vascular
growth (Fig. 1). Concurrently n23 PUFAs favour vasodilatory mechanisms over vasoconstrictive processes by a
variety of possibly interlinked processes (Fig. 6). The
question remains as to why these longchain n23 PUFAs
consistently produce an influence on widely differing
processes consistent with cardiovascular disease prevention
as clearly demonstrated in several large clinical trials
[3,79]. What is evident is that in addition to being
protective against acute cardiovascular events and consequent deleterious effects of myocardial ischaemia including cardiac arrhythmia and tissue damage [18,64,80], the
n23 PUFAs act to prevent pathological and physiological
processes that precipitate ischaemic episodes.
In addition to the established cardiovascular benefits of
n23 PUFAs [2–5], more recent studies have identified
additional protective actions of longchain n23 polyenoic
fatty acids on a myriad of different cellular mechanisms of
pathophysiological consequence. Although, most of these
discoveries have been made in vitro, using cultured cell
lines in acute experiments under defined conditions, it is
likely that such protective actions may in deed be extended
to chronic disease processes such as atherogenesis and the
development of coronary artery disease.
It can also be speculated that the ability of longchain
n23 PUFAs to exert such multiple modes of action (Fig.
7) may provide the biological basis for their wide ranging
cardiovascular protection when compared to specific pharmacological agents directed towards individual cardiovascular pathophysiological mechanisms. Such spec-
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
369
Fig. 6. Pleiotropic actions of longchain n23 PUFAs on the vasculature. Summary of reported beneficial effects exerted by fish oil fatty acids.
Fig. 7. Cardiovascular benefits of longchain n23 PUFAs. Several key pathophysiological events in the cardiovascular disease cascade are beneficially
modulated by longchain n23 PUFAs of marine origin.
trum of potential benefits (Figs. 6 and 7) also suggests
longchain n23 PUFAs to possess substantial pleiotropic
actions, akin to those observed with certain pharmacological interventions [81]. It remains to be determined
what additional vascular benefits may be derived from
these longchain n23 PUFAs.
[5]
[6]
[7]
[8]
References
[9]
[1] Dyerberg J, Bang HO, Stoffersen E et al. Eicosapentaenoic acid and
prevention of thrombosis and atherosclerosis. Lancet 1978;2:117–
119.
[2] Schmidt EB. Fish consumption, n23 fatty acids in cell membranes,
and heart rate variability in survivors of myocardial infarction with
left ventricular dysfunction. Am J Cardiol 1997;74:1670–1673.
[3] Angerer P, von Schacky C. n23 Polyunsaturated fatty acids and the
cardiovascular system. Curr Opin Lipidol 2000;11:57–63.
[4] Mori TA, Beilin LJ. Long-chain omega 3 fatty acids, blood lipids
[10]
[11]
and cardiovascular risk reduction. Curr Opin Lipidol 2001;12:11–
17.
Von Schacky C. n23 fatty acids and the prevention of coronary
atherosclerosis. Am J Clin Nutr 2000;71:224S–227S.
Gibbons GH. Endothelial function as a determinant of vascular
function and structure: A new therapeutic target. Am J Cardiol
1997;79:3–8.
Noll G, Luscher TF. The endothelium in acute coronary syndromes.
Eur J Cardiol 1998;19:C30–C38.
Harris WS, Rambjor GS, Windsor SL, Diederich D. n23 fatty acids
and urinary excretion of nitric oxide metabolites in humans. Am J
Clin Nutr 1997;65:459–464.
Nestel PJ. Fish oil and cardiovascular disease: lipids and arterial
function. Am J Clin Nutr 2000;71:228S–231S.
Goodfellow J, Bellamy MF, Ramsay MW, Jones CJH, Lewis MJ.
Dietary supplementation with marine omega-3 fatty acids improve
systemic large artery endothelial function in subjects with hypercholesterolemia. J Am Coll Cardiol 2000;35:265–270.
Asano M, Nakajima T, Iwasawa K et al. Inhibitory effects of v-3
polyunsaturated fatty acids on receptor mediated non-selective
cation currents in rat A7r5 vascular smooth muscle cells. Br J
Pharmacol 1997;120:1367–1375.
370
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
[12] Asano M, Nakajima T, Hazama H et al. Influence of cellular
incorporation of n23 eicosapentaenoic acid on intracellular Ca 21
concentration and membrane potential in vascular smooth muscle
cells. Atherosclerosis 1998;138:117–127.
[13] Meydani M. Omega-3 fatty acids alter soluble markers of endothelial function in coronary heart disease patients. Nutr Rev 2000;58:56–
59.
[14] Head RJ, Mano MT, Bexis S, Howe PRC, Smith RM. Dietary fish
oil administration retards the development of hypertension and
influences vascular neuroeffector function in stroke-prone hypertensive rats (SHR-SP). Prostaglandins Leukot Essent Fatty Acids
1991;44:119–122.
[15] Mano MT, Bexis S, Abeywardena MY et al. Fish oils modulate
blood pressure and vascular contractility in the rat and vascular
contractility in the primate. Blood Press 1995;4:177–186.
[16] Chin JPF. Marine oils and cardiovascular reactivity. Prostaglandins
Leukot Essent Fatty Acids 1994;50:211–222.
[17] Bexis S, Lungershausen YK, Mano MT et al. Dietary fish oil
administration retards blood pressure development and influences
vascular properties in the spontaneously hypertensive rat (SHR) but
not in the stroke-prone spontaneously hypertensive rat (SHR-SP).
Blood Press 1994;3:120–126.
[18] McLennan PL, Howe P, Abeywardena MY et al. The cardiovascular
protective role of docosahexaenoic acid. Eur J Pharmacol
1996;300:83–89.
[19] Mori TA, Bao DQ, Burke V, Puddey IB, Beilin LJ. Docosahexaenoic
acid but not eicosapentaenoic acid lowers ambulatory blood pressure
and heart rate in humans. Hypertension 1999;34:253–260.
[20] Mori TA, Watts GF, Burke V, Hilme E, Puddey IB, Beilin LJ.
Differential effects of eicosapentaenoic acid and docosahexaenoic
acid on vascular reactivity of the forearm microcirculation in
hyperlipidemic, overweight men. Circulation 2000;102:264–1269.
[21] Stier CT, Itskovitz HD. Thromboxane A 2 and the development of
hypertension in spontaneously hypertensive rats. Eur J Pharmacol
1998;146:129–135.
[22] Engler MB, Engler MM. Docosahexaenoic acid induced vasorelaxation in hypertensive rats: Mechanisms of action. Biol Res Nurs
2000;2:85–95.
[23] Engler MB, Engler MM, Browne A, Sun YP, Sievers R. Mechanisms of vasorelaxation induced by eicosapentaenoic acid (20:5
n23) in WKY rat aorta. Br J Pharmacol 2000;131:1793–1799.
[24] Terano T, Shiina T, Tamura Y. Eicosapentaenoic acid suppressed the
proliferation of vascular smooth muscle cells through modulation of
various steps of growth signals. Lipids 1996;31:S301–S304.
[25] Nakayama M, Fukuda N, Watanabe Y et al. Low dose eicosapentaenoic acid inhibits the exaggerated growth of vascular smooth
muscle cells from spontaneously hypertensive rats through suppression of transforming growth factor-b. J Hypertens 1999;17:1421–
1430.
[26] Diep QN, Touyz RM, Schiffrin EL. Docosahexaenoic acid, a
peroxisome proliferator-activated receptor-a ligand, induces apoptosis in vascular smooth muscle cells by stimulation of p38 mitogenactivated protein kinase. Hypertension 2000;36:851–855.
[27] Fischer S, Weber PC. Prostaglandin I 3 is formed in vivo in man after
dietary eicosapentaenoic acid. Nature 1984;307:165–168.
[28] Weber PC. Clinical studies on the effects of n23 fatty acids on cells
and eicosanoids in the cardiovascular system. J Intern Med
1989;225:61–68.
[29] Abeywardena MY, Fischer S, Schweer H, Charnock JS. In vivo
formation of metabolites of prostaglandins I 2 and I 3 in the marmoset
monkey (Callthrix jacchus) following dietary supplementation with
tuna fish oil. Biochim Biophys Acta 1989;1003:161–166.
[30] De Caterina R, Gianessi D, Mazzone A et al. Vascular prostacyclin is
increased in patients ingesting v-3 polyunsaturated fatty acids
before coronary artery by-pass graft surgery. Circulation
1990;82:428–438.
[31] Abeywardena MY, McLennan PL, Charnock JS. Differential effects
[32]
[33]
[34]
[35]
[36]
[37]
[38]
[39]
[40]
[41]
[42]
[43]
[44]
[45]
[46]
[47]
[48]
[49]
[50]
of dietary fish oil on myocardial prostaglandin I 2 and thromboxane
A 2 production. Am J Physiol 1992;260:H379–H385.
Abeywardena MY, McLennan PL, Charnock JS. Differences between in vivo and in vitro production of eicosanoids following
long-term dietary fish oil supplementation in the rat. Prostaglandins
Leukot Essent Fatty Acids 1991;42:159–165.
Swann PG, Venton DL, Le Breton GC. Eicosapentaenoic acid and
docosahexaenoic acid are antagonists at the thromboxane A 2 / prostaglandin H 2 receptor in human platelets. FEBS Lett 1989;243:244–
246.
Abeywardena MY, Head RJ. Differential antagonism by DHA and
EPA at the thromboxane-A 2 and isoprostane receptors in rat aorta
(abstr). 4th Congress of ISSFAL, June 4–9, Japan, 2000, p. 68.
Saito J, Terano T, Hirai A, Shiina T, Tamura Y, Saito Y. Mechanisms of enhanced production in cultured rat vascular smooth
muscle cells enriched with eicosapentaenoic acid. Atherosclerosis
1997;131:219–228.
Achard F, Gilbert M, Benistant C et al. Eicosapentaenoic and
docosahexaenoic acids reduce PGH synthase-1 expression in bovine
aortic endothelial cells. Biochem Biophys Res Commun
1997;241:513–518.
Benistant C, Achard F, Ben Salma S, Lagarde M. Docosapentaenoic
acid (22:5 n23): metabolism and effect on prostacyclin production
in endothelial cells. Prostaglancins Leukot Essent Fatty Acids
1996;55:287–292.
Fischer S, Vischer A, Preac-Mursic V, Weber PC. Dietary docosahexaenoic acid is retroconverted in man to eicosapentaenoic acid which
can be quickly transformed to prostaglandin I 3 . Prostaglandins
1987;34:367–375.
Lawson DL, Mehta JL, Saldeen K, Mehta P, Saldeen TGP. Omega-3
polyunsaturated fatty acids augment endothelium-dependent vasorelaxation by enhanced release of EDRF and vasodilator prostaglandins. Eicosanoids 1991;4:217–223.
Omura M, Kobayashi S, Mizukumi Y et al. Eicosapentaenoic acid
(EPA) induces Ca 21 independent activation and translocation of
endothelial nitric oxide synthase and endothelium-dependent vasorelaxation. FEBS Lett 2001;487:361–366.
Sametz W, Jeschek M, Juan H, Wintersteiger R. Influence of
polyunsaturated fatty acids on vasoconstrictions induced by 8-isoPGF2a and 8-iso-PGE2. Pharmacology 2000;60:155–160.
Nitta K, Uchida K, Tsutsui T et al. Eicosapentaenoic acid inhibits
mitogen-induced endothelin-1 production and DNA synthesis in
cultured bovine mesengial cells. Am J Nephrol 1998;18:164–170.
Hardy P, Dumont I, Battacharya M et al. Oxidants, nitric oxide and
prostanoids in the developing ocular vasculature: a basis for
ischaemic retinopathy. Cardiovasc Res 2000;47:489–509.
Dyer SM, Taylor DA, Bexis S, Hime NJ, Frewin DB, Head RJ.
Identification of a non-endothelial cell thromboxane-like constrictor
response and its interaction with the renin-angiotensin system in the
aorta of spontaneously hypertensive rats. J Vasc Res 1994;31(1):52–
60.
Abeywardena MY, Head RJ. Dietary polyunsaturated fatty acid and
antioxidant modulation of vascular dysfunction in the spontaneously
hypertensive rat. Prostaglandins Leukot Essent Fatty Acids
2001;65:91–97.
Chin PF, Dart M. How do fish oils affect vascular function? Clin
Exp Pharmacol Physiol 1995;22:71–81.
Okuda Y, Kawashima K, Sawada T et al. Eicosapentaenoic acid
enhances nitric oxide production by cultured human endothelial
cells. Biochem Biophys Res Commun 1997;232:487–491.
Morrow JD, Chen Y, Brame CJ et al. The Isoprostanes: unique
prostaglandin-like products of free radical initiated lipid peroxidation. Drug Metab Rev 1999;31:117–139.
Mezzetti A, Cipollone F, Cuccurullo F. Oxidative stress and
cardiovascular complications in diabetes: isoprostanes as new
markers on an old paradigm. Cardiovasc Res 2000;47:475–488.
Wilson SH, Best PJM, Lerman LO, Holmes DR, Richardson DM,
M.Y. Abeywardena, R. J. Head / Cardiovascular Research 52 (2001) 361 – 371
[51]
[52]
[53]
[54]
[55]
[56]
[57]
[58]
[59]
[60]
[61]
[62]
[63]
[64]
[65]
[66]
Lerman A. Enhanced coronary vasoconstriction to oxidative stress
product, 8-epi-prostaglandin F2a in experimental hypercholestrolemia. Cardiovasc Res 1999;44:601–607.
Jourdan KB, Mitchell JA, Evans TW. Release of isoprostanes by
human pulmonary artery in organ culture: A cyclooxygenase and
nitric oxide dependent pathway. Biochem Biophys Res Commun
1997;233:668–672.
Chen LY, Lawson DL, Mehta JL. Reductions in human neutrophil
superoxide anion generation by n23 polyunsaturated fatty acids:
Role of cyclooxygenase products and endothelium-derived relaxing
factor. Thromb Res 1994;76:317–322.
Chen MF, Hsu HC, Chen WJ et al. Fish oil supplementation
attenuates free radical generation in short-term coronary occlusionreperfusion in cholesterol fed rabbits. Prostaglandins 1994;47:307–
317.
Mori TA, Puddey IB, Burke V et al. Effect of v-3 fatty acids on
oxidative stress in humans: GCMS measurement of urinary F 2 isoprostane excretion. Redox Rep 2000;5:45–46.
Helmer ME, Cook HW, Lands WEM. Prostaglandin biosynthesis
can be triggered by lipid peroxides. Arch Biochem Biophys
1979;193:340–345.
Tomasian D, Keaney J, Vita JA. Antioxidants and the biocativity of
endothelium-derived nitric oxide. Cardiovasc Res 2000;47:426–435.
Kang JX, Leaf A. Prevention of fatal cardiac arrhythmias by
polyunsaturated fatty acids. Am J Clin Nutr 2000;71:202S–207S.
Xiao YF, Gomez AM, Morgan JP, Lederer WJ, Leaf A. Suppression
of voltage gated L-type Ca 21 currents by polyunsaturated fatty acids
in adult and neonatal rat cardiac myocytes. Proc Natl Acad Sci USA
1997;94:4182–4187.
Xiao YF, Wright SN, Wang GK, Morgan JP, Leaf A. N23 fatty acids
suppress voltage-gated Na 1 currents in HEK293t cells transfected
with the a-subunit of the human cardiac Na 1 channel. Proc Natl
Acad Sci USA 1998;95:2680–2685.
Leifert WR, McMurchie EJ, Saint DA. Inhibition of cardiac sodium
currents in adult rat myocytes by n23 polyunsaturated fatty acids. J
Physiol 1999;520:671–679.
McLennan PL, Abeywardena MY, Charnock JS. Dietary fish oil
prevents ventricular fibrillation following coronary artery occlusion
and reperfusion. Am Heart J 1988;116:709–717.
Abeywardena MY, Charnock JS. Dietary lipid modification of
myocardial eicosanoids following ischaemia and reperfusion in the
rat. Lipids 1995;30:1151–1156.
Charnock JS. Lipids and cardiac arrhythmia. Prog Lipid Res
1994;33:355–385.
Billman GE, Kang JX, Leaf A. Prevention of sudden cardiac death
by dietary pure v-3 polyunsaturated fatty acids in dogs. Circulation
1999;99:2452–2457.
Singleton CB, Valenzuela SM, Walker BD et al. Blockade by n23
polyunsaturated fatty acid of the Kv4.3 current stably expressed in
Chinese hamster ovary cells. Br J Pharmacol 1999;127:941–948.
Christensen JH, Gustenhoff P, Korup E et al. Effect of fish oil on
heart rate variability in survivors of myocardial infarction: a double
blind randomised controlled trial. Br Med J 1996;312:677–678.
371
[67] Christensen JH, Christensen MS, Dyerberg J, Schmidt EB. Heart
rate variability and fatty acid content of red blood cell membranes: a
dose response study with n23 fatty acids. Am J Clin Nutr
1999;70:331–337.
[68] Shiina T, Terano T, Saito Y, Tamura Y, Yoshida S. Eicosapentaenoic
acid and docosahexaenoic acid suppress the proliferation of vascular
smooth muscle cells. Atherosclerosis 1993;104:95–103.
[69] Terano T, Shiina T, Yamamoto K et al. Eicosapentaenoic acid and
docosahexaenoic acid inhibit DNA synthesis through inhibiting cdk2
Kinase in vascular smooth muscle cells. Ann NY Acad Sci
1997;811:369–377.
[70] Lehr HA, Hubner C, Finckh B, Nolte D, Beiseigel U, Kohlschutter
A, Messmer K. Dietary fish oil reduces leukocyte / endothelium
interaction following systemic administration of oxidatively modified low-density lipoprotein. Circulation 1991;84:1725–1731.
[71] De Caterina R, Liao JK, Libby P. Fatty acid modulation of
endothelial activation. Am J Clin Nutr 2000;71:213S–223S.
[72] Weber C, Erl W, Pietsch A. Danesch, Weber P.C. Docosahexaenoic
acid selectively attenuates induction of vascular cell adhesion
molecule-1 and subsequent monocytic cell adhesion to human
endothelial cells stimulated by tumour necrosis factor-alpha. Arterioscler Thromb Vasc Biol 1995;15:622–628.
[73] De Caterina R, Libby P. Control of endothelial leukocyte adhesion
molecules by fatty acids. Lipids 1996;31:S57–S63.
[74] Khalfoun B, Thibault G, Bardos P, Lebranchu Y. Docosahexaenoic
and eicosapentaenoic acids inhibit in vitro human lymphocyteendothelial cell adhesion. Transplantation 1996;62:1649–1657.
[75] De Caterina R, Bernini W, Carluccio MA, Liao JK, Libby P.
Structural requirements for inhibition of cytokine-induced endothelial activation by unsaturated fatty acids. J Lipid Res 1998;39:1062–
1070.
[76] Stubbs CD, Smith AD. The modification of mammalian membrane
polyunsaturated fatty acid composition in relation to membrane
fluidity and function. Biochim Biophys Acta 1984;779:89–137.
[77] Hashimoto M, Hossain S, Yamasaki H, Yazawa K, Masumura S.
Effects of eicosapentaenoic acid and docosahexaenoic acid on
plasma membrane fluidity of aortic endothelial cells. Lipids
1999;34:1297–1304.
[78] Pound EM, Kanf JX, Leaf A. Partitioning of polyunsaturated fatty
acids, which prevent cardiac arrhythmias, into phospholipid cell
membranes. J Lipid Res 2001;42:346–351.
[79] GISSI-Prevenzione Investigators. Dietary supplementation with n23
polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet 1999;354:447–
455.
[80] Otsuji S, Shibata N, Hirota H, Akagami H, Wada A. Highly purified
eicosapentaenoic acid attenuates tissue damage in experimental
myocardial infarction. Jpn Circ J 1993;57:335–343.
[81] White CM. Pharmacological effects of HMG-CoA reductase inhibitors other than lipoprotein modulation. J Clin Pharmacol
1999;39:111–118.