Sensory Neurons With Afferents From Hind Limbs
Enhanced Sensitivity in Secondary Hypertension
Peter Linz, Kerstin Amann, Wolfgang Freisinger, Till Ditting, Karl F. Hilgers, Roland Veelken
Downloaded from http://hyper.ahajournals.org/ by guest on June 17, 2017
Abstract—Sensory nerve fibers from the dorsal root ganglia (DRG) may contribute to the regulation of peripheral vascular
resistance. Axons of DRG neurons of the lower thoracic cord project mainly to resistance vessels in the lower limbs,
likely opposing the vasoconstrictor effects of the sympathetic activity. This mechanism might be of importance in
hypertension with increased sympathetic activity. We tested the hypothesis that sensory neurons of the DRG in the lower
thoracic cord show an altered sensitivity to mechanical stimuli in hypertension. Neurons from DRG (T11 to L1) of rats
with hypertension (2 kidney-1 clip hypertensive rats and 5 of 6 nephrectomized rats) were cultured on coverslips.
Current time relationships were established with whole-cell patch recordings. Cells were characterized under control
conditions and after exposure to hypoosmotic solutions to induce mechanical stress. Neurons with projections to the
kidney were studied for comparison. The hypoosmotic extracellular medium induced a significant change in
conductance of the cells in all of the groups of rats. In hypertensive rats, responses of cells with hindlimb axons were
significantly different from controls: (2 kidney-1 clip hypertensives: ␦⫺351⫾52 pA and 5 of 6 nephrectomized rats:
␦⫺372⫾43 pA versus controls: ␦⫺190⫾25 pA; P⬍0.05). Responses of DRG cells with renal afferents to mechanical stress
were unaffected. Neurons from DRG in the lower thoracic cord with projections to the lower limbs exhibited an increased
sensitivity to mechanical stress. We speculate that this observation may indicate an increased activity of these neurons, their
axons, and neurotransmitters in the control of resistance vessels in hypertension. (Hypertension. 2006;47[part 2]:527-531.)
Key Words: hindlimb 䡲 hypertension, renal 䡲 mechanosensitivity 䡲 hypertension, secondary 䡲 kidney
䡲 nephrectomy 䡲 rats
T
cally characterized as C-fibers10 that, in addition, were often
observed to be peptidergic secreting substances like substance P (SP) and calcitonin gene-related peptide
(CGRP).11,12 Again, little is known about perivascular innervation of vessels relevant in hypertension. Some investigations were published on the perivascular CGRP-containing
innervation of the mesenteric artery.13,14 Only scarce reports
on hindlimb circulation are available.15 However, those latter
investigations would be more relevant to answer the question
about the extent to which vascular sensory, peptidergic
afferent nerves are of importance in hypertension.
One reason why putative perivascular fibers of resistance
vessels were as yet not or seldom investigated is the fact that
they are very difficult to study with available neurophysiological methods, which prove to be tedious even with respect
to easier accessible sensory axons.16 This problem could be
partly overcome with recently developed approaches using
neuronal cell cultures in vitro from, for example, the nodose
ganglion, where the first neuron of afferent pathways from
arterial or cardiac baroreceptors1718 can be found that were
investigated with the patch clamp technique, because it is
likely that the neuronal cell body responds to mechanical
he autonomic innervation of the cardiovascular system is
seen as an important controller of the cardiovascular system.1–3 This is not only true for the efferent sympathetic nerve
activity but also for afferent neural pathways.4 Malfunction of
these systems is likely to be involved in the development and
maintenance of hypertension. Of major importance in this
respect are baroreceptor afferents from the carotic arteries and
the aortic arch, which exert a strong influence on sympathetic
outflow in health and hypertension.5 A comparable lesser role
might be attributed to cardiac baroreceptor afferents exerting a
considerable control on renal nerve activity 6 and renal afferents
from baroreceptors in the kidney and its pelvis.7
Interestingly, almost nothings is known about neural afferents from resistance vessels, for example, in the extremities
or the skin, although these arteries are exposed to strong
mechanical stress because of pulsatile blood pressure that
increases in hypertension.8 It seems unlikely that afferent
innervation is lacking in the extremities or, if present, without
influence on cardiovascular autonomic nerve function under
the mentioned physiological conditions.
It is known from other investigations that afferent nerve
fibers from skin9 and other organs can be electrophysiologi-
Received October 4, 2005; first decision October 22, 2005; revision accepted November 29, 2005.
From the Department of Internal Medicine 4/Nephrology and Hypertension (P.L., W.F., T.D., K.F.H., R.V.), Department of Pathology (K.A.),
University of Erlangen-Nürnberg, Erlangen, Germany.
Correspondence to Roland Veelken, Department of Medicine 4, University of Erlangen-Nürnberg, Loschgestraße 8, 91054 Erlangen, Germany. E-mail
[email protected]
© 2006 American Heart Association, Inc.
Hypertension is available at http://www.hypertensionaha.org
DOI: 10.1161/01.HYP.0000199984.78039.36
527
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March 2006 Part II
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stimuli in a similar manner to the endings of afferent axons.19
The respective neuronal cell bodies could be identified by
applying specialized dyes to the very sites on the carotic
arteries or the surface of the heart where the nerve endings of
the afferent axons could be found to retrogradely stain
neurons in the nodose ganglion.18 The described experimental
procedure can be easily adapted to other sites of interest to
identify the first neurons of other sensory afferent pathways.
Furthermore, this approach allows us to elucidate the potential mechanisms responsible for the mechanosensitivity of
sensory nerve endings,20 although really specific inhibitors of
mechanosensitive ion channels, for example, are still not
available, and existing concepts to explain the mechanosensitivity of afferent nerve fibers are far from being undisputed.6
Hence, we wanted to test the hypothesis that the response of
neurons from dorsal root ganglia (DRG) with axons to the
hindlimb vasculature of rats exhibit an altered sensitivity to
mechanical stimulation in models of secondary hypertension,
namely in 2 kidney 1 clip rats and 5 of 6 nephrectomized rats
as compared with respective normotensive animals.
We investigated neurons from DRG with axons to the
kidneys as control samples, because we knew from preliminary experiments that both groups of neurons can be found in
the DRG of the vertebrae Th 11 to L2. We used hypoosmolar
media to expose cultivated neurons to mechanical stress as
described previously.
Methods
For the experiments, male Sprague-Dawley rats (Ivanovas, Kisslegg,
Germany) weighing 250 to 300 g were maintained in cages at
24⫾2°C. They were fed a standard rat diet (no. C-1000, Altromin)
containing 0.2% sodium by weight and were allowed free access to
tap water. All of the procedures performed on animals were done in
accordance with the guidelines of the American Physiological
Society and approved by the local government.
Preparation of Hypertensive Models in Rats
All of the procedures performed in animals were done in accordance
with guidelines of the American Physiological Society. 2K1C
renovascular hypertension was induced in male Sprague-Dawley rats
as described previously.21 Control animals were sham operated. The
animals were followed by weekly measurements of weight and
systolic blood pressure by tail-cuff plethysmography. In contrast to
the model used by Mann et al,22 lower perfusion pressure of the
poststenotic kidney does not occur immediately after the procedure
but develops slowly with the growth of the animal over a period of
ⱖ1 week. Animals were only included in the 2K1C groups if systolic
blood pressure was ⬎150 mm Hg. Animals that failed to thrive or
lost weight were excluded after 2 weeks.
Hypertension after 5/6 nephrectomy was induced by subtotal nephrectomy or sham operation and subsequently fed using a pair-feeding
protocol to assure a similar food intake in sham and animals that had
undergone surgery. As described before,23 the rats underwent 2-step
subtotal nephrectomy (removal of right kidney; 7 days later, weightcontrolled surgical removal of cortical tissue of the hypertrophied left
kidney corresponding to 66% of the weight of the right kidney).
Measurement of Arterial Blood Pressure
After the development of increased blood pressure (median time of 4
weeks) in clipped or renally ablated rats, animals were equipped with a
femoral artery catheter under ketamine/xylazine anesthesia, and intraarterial blood pressure was measured in conscious rats 4 hours after
anesthesia via a transducer connected to a polygraph (Hellige).
Labeling of Mechanosensitive Dorsal Root Ganglion
Neurons With Hindlimb or Renal Afferents
To identify putative mechanosensitive neurons with renal or hindlimb
afferents, we labeled these cells using the dicarbocyanine dye 1,1⬘
dioleyl-3,3,3⬘ tetramethyl-indocarbocyaline methansulfonate (D9–DiI,
50 mg/mL in dimethyl sulfoxide, Molecular Probes) either by subcapsular application of DiI (5 ␮L of 10 mg/mL) in both kidneys or
application underneath the fascia onto the large muscles of both upper
hindlimbs 1 week before harvesting of respective neurons from DRG
T11 to L2.17,18 Care was taken to prevent back leak or spreading of the
substance to surrounding tissue. Initially rats were anesthetized with a
500-␮L bolus injection of hexobarbital (20 mg/mL) IP. After the
insertion of a venous line, appropriate anesthesia was achieved with an
IV maintenance infusion of hexobarbital (80 ␮g/100 g per minute)
through the venous femoral catheter. We allowed 1 week for DiI to be
transported back to the neuronal cells in the DRG. The subscapsular
renal injection of DiI could be brought about with minor surgery. Only
small incisions through skin and muscles were necessary to expose renal
poles. Analgetic drugs were not necessary, and the animals recovered
readily.
Neuronal Cell Culture
Respective rats were anesthetized with hexobarbital as described
above, the animals decapitated, and DRG from T11 to L2 dissected.
Primary cultures of neurons from the DRG were obtained by
mechanical and enzymatic dissociation by adapting protocols described previously by others.17 The ganglia were incubated with
trypsin (1 mg/mL), collagenase (1 mg/mL), and DNase (0.1 mg/mL)
in modified L-15 medium for 1 hour at 37°C. Enzymatic activity was
terminated by the addition of soybean trypsin inhibitor (2 mg/mL),
BSA (1 mg/mL), and CaCl2 (3 mmol/L) in modified L-15 medium,
and the ganglia were triturated using sterile siliconized Pasteur
pipettes to dissociate individual cells. After centrifugation, the cells
were resuspended in a modified L-15 medium with 5% rat serum and
2% chick embryo extract and plated on polylysine-coated glass
coverslips. 5-Fluorodeoxy-2-uridine (80 ␮mol/L) was added to
prevent the proliferation of nonneuronal cells. The cells were plated
on coverslips for 1 day for electrophysiological experiments in a
modified L-15. To demonstrate that labeled cells were neurons, all of
the cells used for experimental procedures were tested for fast
sodium currents during repolarization, which are characteristic for
neuronal cells. Furthermore, a small laser beam (480 nm) powered
by a storage battery was mounted to the patch clamp recording setup.
This equipment allowed for the detection of DiI-stained DRG cells
during the experiments using respective optical filters.
Patch Clamp
Patch recordings18 were obtained from respective neurons using a
recording solution containing 104 mmol/L KCL, 16 mmol/L KOH,
1 mmol/L magnesium ATP, and 10 mmol/L HEPES. The resistances
of the electrodes ranged from 3 to 6 mol/L⍀. The seal resistance was
between 2 and 10 G⍀, and the series resistance was ⬎100 mol/L⍀.
Whole-cell voltage clamp recordings were obtained with the help of
a 200 B Axopatch amplifier (Axon Instruments). Data were sampled
at 5 kHz and stored on a computer hard disk using a commercially
available software package (pClamp, Axon Instruments). Current
time relationships were obtained by exposing neurons to hypoosmolar solution for 5 minutes followed by a 10-minute recovery period.
In general, cells were placed in a 1-chamber laminar flow bath and
perfused at a rate of 0.5 to 1 mL/min by gravity feed lines connected
to fluid reservoirs. Fluid was removed by carefully applied suction
to the bath. The composition of the control bath solution was
120 mmol/L NaCl, 2 mmol/L CaCl2, 1 mmol/L MgCl2, 1 mmol/L
KCl, 10 mmol/L HEPES, and 40 mmol/L mannitol obtaining a
solution of 290 osM. The hypoosmotic solution had the same ionic
content without the mannitol. This solution exhibited an osmolality
of 255 osM. The osmolality of each solution was controlled for using
an osmometer (Micro-Osmometer).
We first exposed the cells to control medium. After we had achieved
stable current time relationships in this solution (5 minutes), the
Linz et al
extracellular medium was changed, and the cells were exposed to the
hypoosmotic medium for 5 minutes to induce mechanical stress. The
hypoosmotic medium was then again replaced with the original extracellular control solution. We only included neurons in the analysis if
their resting membrane potentials was ⬍⫺40 mV.
Experimental Protocols
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In all groups of rats, blood pressure was not only assessed by
tail-cuff plethysmography but also measured directly with an arterial
line as mentioned above. Only cells that stained brightly for DiI in
the light of the laser beam were used for the experiments after
harvest and culturing. Cells with putative neurons from the hindlimbs of hypertensive animals (2K1C or 5/6 nephrectomy) and their
respective controls underwent the protocol for osmomechanical
stimulation. The experimental protocol was also performed in
neurons with putative renal afferents likewise located in DRG of
vertebrae T11 to L2 to use the results from a neuron population with
afferents of a different anatomic site as comparison. The neurons had
to be recorded during the first 2 days after harvesting, because it turned
out that putative differences in the response pattern of different groups
of neurons to mechanical stress gradually diminished in the days to
follow and, eventually, were no longer observable.
Data Analyses
The data were statistically analyzed with ANOVA and Newman–
Keuls post hoc test (where appropriate) using a CSS statistical
software package (StatSoft Inc). Only a priori fixed comparisons
were tested. Statistical significance was defined as P⬍0.05. Data are
given as mean⫾SEM.24
Results
Animals and Blood Pressure
Blood pressure in 5/6 nephrectomized animals (n⫽8) increased up to a mean blood pressure of 138⫾10 mm Hg,
whereas the respective pressure in 2 kidney/1 clip rats (n⫽10)
was significantly higher with 188⫾10 mm Hg (P⬍0.05).
Pooled Sham controls exhibited a mean arterial pressure of
90⫾8 mm Hg (n⫽12).
Sensory Afferents From Hind Limbs
529
pattern of distribution between neurons with hindlimb or
renal afferents could not be served, although the neurons with
renal afferents appeared to be found more often closer to the
ventral portion of the ganglia. After 1 day in culture, DRG
cells could be distinguished in most cases from fibroblast and
other cells by their larger soma. A fraction of these cells
(between 15% and 25%) was brightly labeled with DiI as seen in
the respective cross-sections (Figure 1). The cells clearly labeled
were classified as putative DRG cells with hindlimb or renal
afferents. These cells were used in our experiments after primary
cultures of neurons from the respective DRG were obtained by
mechanical and enzymatic dissociation. No differences in size
could be detected between labeled and unlabeled cells.
Neuron Investigation
During mechanical osmotic stress, dorsal root ganglion cells
with hindlimb afferents exhibited a significantly higher inward current in 2 kidney/1 clip hypertensive rats than in the
respective controls. However, neurons with renal afferents
showed a completely different pattern in these rats, because
no differences in inward current to osmotic stress could be
observed between hypertensive and control animals. Furthermore, the peak inward current of neurons with renal afferents
was numerically identical in renal neurons of hypertensive
and control animals as compared with dorsal root ganglion
cells with hindlimb afferents of 2 kidney/1 clip hypertensive
rats (Figure 2). Interestingly, no difference could be observed
in the responsiveness of renal neurons that could have pointed
to differences because of the fact that in this model 1 kidney
is clipped and 1 kidney is exposed to the increased blood
pressure. In some rats of the clipped group, we labeled right
and left kidneys selectively. Because no differences in the
Labeled Cells In Situ and in Culture
Slices of harvested DRG cells positively stained with DiI
were viewed under epifluorescence with modulation contrast
optics as yellow cells (Figure 1). A clear difference in the
Figure 1. Photomicrographs of DRG (T11 to L2) viewed under
epifluorescence with modulation contrast optics to identify putative dorsal root ganglion cells labeled by DiI with afferents from
hindlimbs (left) and kidneys (right).
Figure 2. DiI-positive DRG neurons with hindlimb afferents were
significantly more sensitive to mechanical stress in 2 kidney-1 clip
(2K/1C) rats as compared with their normotensive Sprague-Dawley
controls. These responses were markedly different in neurons with
afferents to the kidneys: Mechanical stress induced in hypertensive
and control animals is completely similar, with quite considerable
increases in inward currents (*P⬍0.05 hindlimb control vs hindlimb
2K1C).
530
Hypertension
March 2006 Part II
response pattern could be observed, we subsequently returned
to the standard protocol injecting DiI subcapsularly into both
kidneys at the same time.
In 5 of 6 nephrectomized rats, a similar pattern to the 2
kidney/1 clip rats was observed. Again, DRG neurons with
putative hindlimb afferents were significantly more sensitive
to mechanical stress in hypertensive animals than in controls,
whereas such a difference could not be observed with respect
to cells with renal afferents. As in 2 kidney/1 clip rats, the
peak inward current of neurons with renal afferents was again
numerically identical in renal neurons of hypertensive and
control animals as compared with dorsal root ganglion cells
with hindlimb afferents of rats with renal ablation (Figure 3).
Discussion
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We demonstrated for the first time that neurons with hindlimb
afferents of 2 different rat models with secondary hypertension that putatively innervate resistance vessels revealed an
altered sensitivity to mechanical stress in a cell culture model
that potentially allows for the mechanistic investigations of
mechanosensitivity and its alteration in vascular afferent
nerve fibers. The observed differences in neurons from
hypertensive and normotensive control rats cannot be completely unspecific, because this response pattern to mechanical stress could not be observed in neurons with afferents
from the kidneys. Furthermore, in normotensive animals, we
observed differences in the peak inward currents between
neurons with afferents from different sites (hindlimb and
kidney). Finally, the alterations observed in dorsal root cells
with projections from the hindlimb might reflect a general
alteration of the sensitive innervation of muscular vasculature, for example, resistance vessels, because the degree of
Figure 3. In 5 of 6 nephrectomized rats, a similar pattern to that
in 2 kidney-1 clip (2K/1C) rats was observed. DiI-positive DRG
neurons with hindlimb afferents were significantly more sensitive
to mechanical stress in hypertensive animals than in controls,
whereas such a difference could not be observed with respect
to cells with renal afferents. *P⬍0.05 hindlimb control vs hindlimb 2K1C.
the increase in blood pressure was obviously not directly
associated with the increased sensitivity of these cells to
mechanical stress. Other than resistance vessels, we cannot
completely exclude that some hindlimb afferents and the respective neurons innervated other structures of the hindlimb serving,
for example, muscle receptors, nociceptors, or thermoceptors.
However, because the observed responses were relatively homogenous, we assume in any case that a quite uniform and
specific alteration in the sensory innervation of the hindlimb
afferents occurred in the models of secondary hypertension used.
The differences in mechanosensitivity that we observed
between neurons in hypertensive and normotensive animals
during the first 2 days after harvesting were obviously related
to the hypertensive state, because they disappeared during the
subsequent days. The importance of these alterations in mechanosensitivity could be only assessed in animals with selective
ablation of neurons with hindlimb afferents to observe whether
under these circumastances hypertension is less pronounced,
hindlimb resistance decreased, or structural changes in resistance
vessels or other areas of the hindlimbs ameliorated.
The question of how far the putatively altered nerve traffic
from hindlimb afferents will control efferent sympathetic
nerve activity to hindlimb vessels can not as yet be answered.
It is likely that this afferents will decrease sympathetic nerve
activity comparable to central input from arterial,25 cardiac,26
or renal baroreceptors.27 However, sympathoexcitatory afferents have been described as well.28
We did not determine the peptide content of our neurons;
however, production of substances like CGRP is likely.
Results of experiments in rats suggested that CO2 liberated
from exercising skeletal muscle activated capsaicin-sensitive
perivascular sensory nerves locally, which resulted in the
release of CGRP from their peripheral endings, and then the
released peptide caused local vasodilatation.15 In spontaneously hypertensive rats, long-term treatment with angiotensin
II–inhibiting drugs significantly increased the density of
CGRP-containing nerve fibers in mesenteric arteries, that is,
those normally reduced in hypertensive animals as compared
with normotensive controls.29 These results suggested that
long-term inhibition of the renin-angiotensin system in SHR
prevents remodeling of CGRP-ergic nerve fibers and prevents
the reduction of CGRP-ergic nerve function in this hypertensive model.30 Nothing is known about the relation of putative
afferent nerve traffic and impaired mechanosensitivity to an
altered production and release of CGRP by perivascular
nerves of the mesenteric artery or resistance vessels.
With respect to neurons with renal afferents, we could not
observe any differences between normotensive and hypertensive animals. One could argue that this is a sign for the fact
that mechanical forces with respect to the hypertensive
kidneys and their afferent nerve fibers are certainly not
involved in the development and maintenance of hypertension. The fact that renal afferent deafferentiation could delay
the rise in blood pressure in most of hypertensive animals
known16 could be disputed with the argument that chemical
stimulation of these fibers might be predominantly involved.31 However, one should take into account that increases of renal interstitial pressure have been monitored in
pathological situations in rats 32 so that more tonic mechanical
Linz et al
forces within the kidney might induce less severe alterations in
neuronal structures than the more severe forces of an increased
pulsatile blood pressure, eventually even inducing vascular
damage8. A better argument against the importance of altered
stimulation of renal afferents by mechanical forces in hypertension might be, rather (at least in the 2 kidney/1 clip model), the
fact that the responsiveness of renal neurons from respective
DRG was obviously not influenced by the origin of the afferent
axons from the clipped or the contralateral kidney in our
experiments.8 Does this also mean that a release of CGRP is
unlikely from renal afferents in these models? We cannot
comment on this question from our experiments, but recent
results on the renoprotective properties of CGRP in experimental
hypertension do not support this assumption.33–35 Rather, one
could hypothesize that afferent sensory nerve impulses and
efferent release of peptides from endings of these very nerves
might be controlled independently from one another.
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Perspectives
An additional elucidation of the functional role of afferent
nerve fibers from the hindlimb compartment in hypertensive
models, for example, in rats, cannot rely on neurophysiological nerve recordings because of the delicate nature of the
fiber elements involved. Rather, selective dorsal rhizotomies
combined with blood flow assessments and morphological
investigations of vascular damage, as well as the role of
neuronally secreted peptides, like CGRP, in resistant vessels,
might be helpful. Those investigations could answer the question
of how far mechanosensitive vascular afferent nerve fibers might
be involved in hypertension and related vascular damage.
Acknowledgments
This work was supported by a grant-in-aid from the Deutsche
Forschungsgemeinschaft (KFO 106-1 and 106-2).
References
1. Wyss JM, Carlson SH. The role of the nervous system in hypertension.
Curr Hypertens Rep. 2001;3:255–262.
2. Sripairojthikoon W, Wyss JM. Cells of origin of the sympathetic renal
innervation in rat. Am J Physiol. 1987;252:F957–F963.
3. Beevers G, Lip GY, O’Brien E. ABC of hypertension: The pathophysiology of hypertension. BMJ. 2001;322:912–916.
4. Chapleau MW, Li Z, Meyrelles SS, Ma X, Abboud FM. Mechanisms
determining sensitivity of baroreceptor afferents in health and disease.
Ann N Y Acad Sci. 2001;940:1–19.
5. Stauss HM. Baroreceptor reflex function. Am J Physiol Regul Integr
Comp Physiol. 2002;283:R284 –R286.
6. Ditting T, Linz P, Hilgers KF, Jung O, Geiger H, Veelken R. Putative role
of epithelial sodium channels (ENaC) in the afferent limb of cardio renal
reflexes in rats. Basic Res Cardiol. 2003;98:388 – 400.
7. Kopp UC, Smith LA. Inhibitory renorenal reflexes: a role for substance P or
other capsaicin-sensitive neurons. Am J Physiol. 1991;260:R232–R239.
8. Mulvany MJ. Small artery remodeling in hypertension. Curr Hypertens
Rep. 2002;4:49 –55.
9. Kress M, Petersen M, Reeh PW. Methylene blue induces ongoing activity
in rat cutaneous primary afferents and depolarization of DRG neurons via
a photosensitive mechanism. Naunyn Schmiedebergs Arch Pharmacol.
1997;356:619 – 625.
10. Ditting T, Hilgers KF, Scrogin KE, Stetter A, Linz P, Veelken R. Mechanosensitive cardiac C-fiber response to changes in left ventricular filling,
coronary perfusion pressure, hemorrhage, and volume expansion in rats.
Am J Physiol Heart Circ Physiol. 2005;288:H541–H552.
11. Tiegs G, Bang R, Neuhuber WL. Requirement of peptidergic sensory innervation for disease activity in murine models of immune hepatitis and protection by beta-adrenergic stimulation, J Neuroimmunol. 1999;96:131–143.
Sensory Afferents From Hind Limbs
531
12. Kopp UC, Cicha MZ. Impaired substance P release from renal sensory
nerves in SHR involves a pertussis toxin-sensitive mechanism. Am J
Physiol Regul Integr Comp Physiol. 2004;286:R326 –R333.
13. Kawasaki H, Saito A, Goto K, Takasaki K. Age-related changes in
calcitonin gene-related peptide (CGRP)-mediated neurogenic vasodilation of the mesenteric resistance vessel in SHR. Clin Exp Hypertens A.
1991;13:745–754.
14. Kawasaki H, Nuki Y, Yamaga N, Kurosaki Y, Taguchi T. Decreased
depressor response mediated by calcitonin gene-related peptide (CGRP)containing vasodilator nerves to spinal cord stimulation and levels of
CGRP mRNA of the dorsal root ganglia in spontaneously hypertensive
rats. Hypertens Res. 2000;23:693– 699.
15. Yamada M, Ishikawa T, Yamanaka A, Fujimori A, Goto K. Local neurogenic regulation of rat hindlimb circulation: CO2-induced release of
calcitonin gene-related peptide from sensory nerves. Br J Pharmacol.
1997;122:710 –714.
16. DiBona GF, Kopp UC. Neural control of renal function. Physiol Rev.
1997;77:75–197.
17. Cunningham JT, Wachtel RE, Abboud FM. Mechanosensitive currents in
putative aortic baroreceptor neurons in vitro. J Neurophysiol. 1995;73:
2094–2098.
18. Linz P, Veelken R. Serotonin 5-HT(3) receptors on mechanosensitive
neurons with cardiac afferents. Am J Physiol Heart Circ Physiol. 2002;
282:H1828 –H1835.
19. Harper AA. Similarities between some properties of the soma and sensory
receptors of primary afferent neurones. Exp Physiol. 1991;76:369 –377.
20. Drummond HA, Price MP, Welsh MJ, Abboud FM. A molecular component of the arterial baroreceptor mechanotransducer [see comments].
Neuron. 1998;21:1435–1441.
21. Hartner A, Cordasic N, Goppelt-Struebe M, Veelken R, Hilgers KF. Role
of macula densa cyclooxygenase-2 in renovascular hypertension. Am J
Physiol Renal Physiol. 2003;284:F498 –F502.
22. Mann B, Hartner A, Jensen BL, Hilgers KF, Hocherl K, Kramer BK,
Kurtz A. Acute upregulation of COX-2 by renal artery stenosis. Am J
Physiol Renal Physiol. 2001;280:F119 –F125.
23. Amann K, Rump LC, Simonaviciene A, Oberhauser V, Wessels S, Orth
SR, Gross ML, Koch A, Bielenberg GW, Van Kats JP, Ehmke H, Mall G,
Ritz E. Effects of low dose sympathetic inhibition on glomerulosclerosis
and albuminuria in subtotally nephrectomized rats. J Am Soc Nephrol.
2000;11:1469 –1478.
24. Wallenstein S, Zucker IH, Fleiss JL. Some statistical methods useful in
circulation research. Circ Res. 1980;47:1–9.
25. Malpas SC. What sets the long-term level of sympathetic nerve activity:
is there a role for arterial baroreceptors? Am J Physiol Regul Integr Comp
Physiol. 2004;286:R1–R12.
26. Veelken R. Neural control of kidney function. Kidney Blood Press Res.
1998;21:249 –252.
27. Kopp UC, Buckley-Bleiler RL. Impaired renorenal reflexes in twokidney, one clip hypertensive rats. Hypertension. 1989;14:445– 452.
28. Saleh TM, Connell BJ, Allen GV. Visceral afferent activation-induced
changes in sympathetic nerve activity and baroreflex sensitivity. Am J
Physiol. 1999;276:R1780 –R1791.
29. Kawasaki H. Regulation of vascular function by perivascular calcitonin
gene-related peptide-containing nerves. Jpn J Pharmacol. 2002;88:39–43.
30. Hobara N, Gessei-Tsutsumi N, Goda M, Takayama F, Akiyama S,
Kurosaki Y, Kawasaki H. Long-term inhibition of angiotensin prevents
reduction of periarterial innervation of calcitonin gene-related peptide
(CGRP)-containing nerves in spontaneously hypertensive rats. Hypertens
Res. 2005;28:465– 474.
31. Kopp UC, Cicha MZ, Smith LA. Endogenous angiotensin modulates
PGE(2)-mediated release of substance P from renal mechanosensory nerve
fibers. Am J Physiol Regul Integr Comp Physiol. 2002;282:R19–R30.
32. Patel KP, Carmines PK. Renal interstitial hydrostatic pressure and sodium
excretion during acute volume expansion in diabetic rats. Am J Physiol
Regul Integr Comp Physiol. 2001;281:R239 –R245.
33. Deng PY, Ye F, Cai WJ, Deng HW, Li YJ. Role of calcitonin gene-related
peptide in the phenol-induced neurogenic hypertension in rats. Regul
Pept. 2004;119:155–161.
34. Deng PY, Ye F, Zhu HQ, Cai WJ, Deng HW, Li YJ. An increase in the
synthesis and release of calcitonin gene-related peptide in two-kidney,
one-clip hypertensive rats. Regul Pept. 2003;114:175–182.
35. Supowit SC, Rao A, Bowers MC, Zhao H, Fink G, Steficek B, Patel P,
Katki KA, DiPette DJ. Calcitonin gene-related peptide protects against
hypertension-induced heart and kidney damage. Hypertension. 2005;45:
109 –114.
Sensory Neurons With Afferents From Hind Limbs: Enhanced Sensitivity in Secondary
Hypertension
Peter Linz, Kerstin Amann, Wolfgang Freisinger, Till Ditting, Karl F. Hilgers and Roland
Veelken
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Hypertension. 2006;47:527-531; originally published online January 9, 2006;
doi: 10.1161/01.HYP.0000199984.78039.36
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