AMER. ZOOL., 20:163-172 (1980)
Adaptation of Red Blood Cell Function to Hypoxia and
Temperature in Ectothermic Vertebrates1
STEPHEN C. WOOD
Department of Physiology, University of New Mexico, School of Medicine,
Albttquerque, New Mexico 87131
INTRODUCTION
The main purpose of this paper is to review the role of red cell metabolism and
function in adaptations of ectothermic vertebrates to hypoxia and temperature.
The term adaptation, as used in this article, means an alteration of physiological
function which compensates for a stressful
environmental or organismic factor. Two
such factors of paramount importance to
ectothermic vertebrates are temperature
and oxygen availability. The physiological
function to be examined in terms of adaptability is oxygen transport by blood from
the gas exchange surface to the intracellular sites of O2 utilization.
Hypoxia is best denned as inadequate
uptake of O2 by tissues. The cause may be
environmental (reduced O2 content and/or
partial pressure in the respiratory medium) or organismic. In the latter category
there is a hierarchy of sub-causes proceeding down the "oxygen cascade," i.e., impaired gas exchange, shunt, ventilation/
perfusion mismatch, hypoperfusion, or inappropriate oxygen binding properties of
blood. The "appropriateness" of the oxygen binding properties of blood depends,
in turn, on environmental conditions, i.e.,
the partial pressure of O2 (Po2) in the respiratory medium, and on the efficacy of
gas exchange and degree of shunt.
The position of the oxyhemoglobin dissociation curve (ODC) even with full
knowledge about the environmental oxygen availability, is inadequate information
for conclusions about adaptability of "appropriateness" for tissue oxygenation.
Such conclusions are valid only if information is available on in vivo values of tem-
perature, blood gases (arterial and mixed
venous Po2 and Pco2), pH and oxygen capacity. Furthermore, the position of the
ODC may cause, as well as be affected by,
hypoxia. For example, in vertebrates with
incompletely separated pulmonary and
systemic circulations (lungfishes, amphibians, and reptiles), the arterial hypoxemia
due to right-to-left shunting may lead to
severe arterial desaturation and hypoxia if
the ODC is positioned too far to the right.
Conversely, hypoxia caused by environmental factors can, by influencing the
aerobic metabolism of nucleated red cells
(or anaerobic metabolism of mammalian
red cells), alter (in opposite directions!) the
level of allosteric effectors of hemoglobin
function and shift the position of the ODC.
Thus, although it is often irresistably
tempting (as evidenced below) to assess
physiological meaning from shapes and
positions of ODCs, Bohr factors, and apparent enthalpy (AH) values, such speculations should always be recognized and
identified as just that.
INTERACTION OF TEMPERATURE AND
HYPOXIA
In ectotherms, the obligatory coupling
of tissue temperature and oxygen demand
is, for acute changes in temperature, predictable and well understood. Much less
predictable and poorly understood is the
relationship between temperature and hypoxia. While it is obvious that increased
body temperature may tax the capacity of
the oxygen transport system resulting in
hypoxia, it is also possible for decreased
body temperature to cause hypoxia. For
example, if the organismic factors which
determine
the rate of oxygen transport
1
From the Symposium on Respiratory Pigments pre- down the "O cascade" have a temperature
2
sented at the Annual Meeting of the American Society of Zoologists, 27-30 December 1978, at Rich- coefficient less than that of metabolism, an
increase in body temperature will cause
mond, Virginia.
163
164
STEPHEN C. WOOD
hypoxia. Conversely, if the Q10 of oxygen Physiological significance of
transport is greater than that of metabo- AH in homeotherms
lism, a decrease in body temperature will
The temperature sensitivity of hemoglocause hypoxia. Of the four steps in the "O2 bin-oxygen affinity is an easily understood
cascade,"2 it is the ultimate process, i.e., and measurable phenomenon. However,
diffusion of oxygen from capillaries to cel- the link between biochemistry and physilular sites of utilization that is dependent ology is more difficult to assess, especially
on the position and shape of the ODC. if body temperatures encompass a wide
The adaptability of oxygen affinity, hemo- range (see below). For homeotherms, the
globin subunit cooperativity, and oxygen problems of assessing the physiological imcapacity of blood to environmental and portance of AH are minimal due to the
organismic factors is a major ingredient in small range of body temperature and the
the evolutionary success of ectotherms.
availability of data on in vivo blood gases
and pH.
Some recent data to assess the classical
ADAPTATIONS TO TEMPERATURE
view that the right-shifted ODC due to the
Physical principles
hyperthermia (and lactic acidemia) of
The combination of oxygen molecules heavy exercise is adaptive in increasing tiswith hemoglobin is accompanied by a re- sue O2 uptake was provided by Thomson
lease of heat. It follows (Le Chatelier prin- et al. (1978). They found that the femoral
ciple) that an increase in blood tempera- blood in heavily exercising men had a pH
ture will decrease the oxygen affinity of of 7.27 and a temperature of 40.7. Garby
and Meldon (1977) applied these data to
hemoglobin.
When the temperature of hemoglobin is their mathematical model of tissue oxyraised, the increase in Po2 at constant sat- genation during exercise and found that
uration (right-shifted ODC) is a function the combined effects of acidosis and temof the heat of combination of oxygen with perature (yielding a P50 of 38 torr comhemoglobin (AHo^). The general form of pared with ca. 26 torr for resting individthe van't Hoff isochore is d In K/dT = AH/ uals) would allow the required blood flow
RT2. For oxygen binding by hemoglobin to be 49 ml/100 g/min as opposed to 82 if
the equilibrium constant, K, is equivalent there were no shift in the ODC. It would
to P50 (Hill equation) and the above equa- be very interesting to study the signifition can be restated as d log Po2/d (1/T) = cance of temperature on oxygen delivery
AH/2.303 R. (R is the gas constant, 1.987 in mammals such as desert ungulates
where core body temperature may incal/°K/mole.)
This relationship between temperature crease by almost 5° during running (Tayand oxygen affinity of blood was first de- lor and Lyman, 1972).
scribed by Barcroft and Hill (1909) and the
nature of the bond between heme iron and Physiological significance of
oxygen is such that little or no interspecies A// in ectotherms
variation should occur in temperature senTemperature has a dual action on the
sitivity of hemoglobin (cf., Klotz and Klotz, oxygen affinity of blood: the direct effect
1955). This is generally true for homeo- described above and an indirect effect
therms, i.e., the AH of mammalian hemo- caused by the temperature-induced
globins falls within the range of —9 to —14 changes in blood pH. Anaerobic changes
kcal/mole (Rossi-Fanelli et al., 1964). How- in blood temperature cause the blood pH
ever, as discussed in the following sections, to change by approximately -0.014 u/°C.
there are some interesting exceptions This has striking consequences even in hoamong ectothermic vertebrates.
meotherms when core temperature arterial blood perfuses peripheral tissues operating
at other than core temperature.
2
(1) convection of the respiratory medium, (2) diffusion across the gas exchange surface, (3) convection Reeves (1976) calculated that the pH of
arterial blood would increase to 7.67 in
of blood, (4) diffusion into cells.
ADAPTATIONS OF RED CELLS TO HYPOXIA AND TEMPERATURE
165
1.6
cooled skin capillaries and decrease to 7.35
\Rajo
in exercising (42°C) muscle capillaries. He
Neoceratodus^.
points out that this change in pH with tem1.4
perature, parallel to the change in pH of
neutral water, results in a constant charge
1.2
state on proteins and, presumably, provides for enzymatic activity which is temperature independent.
This phenomenon is of greater significance in ectotherms where in addition to Q-° 08
regional differences in body temperature,
Hb-Solution
core temperature may vary daily by as
O.4%,noDPG
06
much as 20-30°C. If both the temperature
(AH) and proton sensitivity of ectotherm
0.4
hemoglobin have high values, the dual effects of temperature can easily shift the
Q2 position of the ODC so much that oxygen
delivery is affected out of proportion to
3.1
3.2
3.3
3.4
3.5
3.6
3.7
oxygen uptake. Adaptations of metabolic
I/Absolute Temperature X IO3
rate were once described as allowing ec403735 30 25 20 15 10 5
0
totherms to "escape from the tyranny of
Temperature °C
the Arrhenius equation" (Barcroft, 1934).
The following sections consider some anal- FIG. 1. Effect of temperature on the oxygen affinity
purified human hemoglobin A and hemoglobin
ogous and some different strategies allow- of
from several species of fish. (Reprinted from K. Joing hemoglobin function a similar "escape." hansen and C. Lenfant, In Alfred Benzon Sympo-
f '°
Hemoglobins with a reduced A//:
Strategy I
The "strategy"3 of temperature adaptation which employs hemoglobin (or hemoglobin components) with reduced apparent AH values was first described in fish.
As shown in Figure 1, the most dramatic
reduction in temperature sensitivity occurs
with tuna hemoglobin (AH = 1 . 8 kcal/
mole). The fascinating ability of the tuna
to maintain a large core to peripheral temperature gradient (Carey and Teal, 1966)
has prompted some novel speculation concerning the functional significance of the
low AH. Hochachka and Somero (1973)
suggest that if tuna hemoglobin had a normal AH, the cool peripheral blood entering the warm, deep muscles might unload
oxygen so rapidly as to produce gas emboli. Since the large temperature gradient
only develops during active swimming, this
3
To those who would object to the term "strategy"
on the basis that it implies some divine (or otherwise)
inspiration, I plead its acceptability on the basis of the
thoughtful descriptions of "strategies" of adaptation
by Hochachka and Somero (1973).
sium IV, Oxygen Affinity of Hemoglobin and Red
Cell Acid-Base Status. Copenhagen, Munksgaard
1972, with permission of the publisher.)
theory would be difficult to test. Also, the
original data on the AH of tuna hemoglobin was obtained from hemolysates (RossiFanelli and Antonini, 1960). It would be
more relevant to know the AH of whole
blood which, as discussed below, would
probably be even lower than —1.8 kcal/
mole.
A variation on this theme of adaptation
occurs in some fishes with multiple hemoglobins. Chum salmon, for example, have
two hemoglobin components, one with a
normal and the other with reduced sensitivity to temperature and pH (Hashimoto,
1960). Some reasonable speculations about
the significance of this suggest homeostasis
of oxygen delivery during periods of fluctuating body temperature (Johansen and
Weber, 1976). As body temperature increased, the beneficial effect of augmented
oxygen unloading could be provided by
the temperature sensitive hemoglobin,
while the temperature insensitive hemoglobin would assure continued oxygen
166
STEPHEN C. WOOD
1.4
Hb Solution 0.4%
1.2
Ictalurus Nebulosus
(whole blood) _
(e.g., Amia) is that higher body temperatures induce air breathing. When this happens, the higher AH is advantageous in
shifting the ODC into a range of Po2 values
more appropriate for air breathing (Johansen et al., 1970; Johansen and Lenfant, 1972).
Amia Colvo
(whole blood)
1.0 mM OPG
v
1.0
20° c \
0.8
24»C
Q6
Mechanism of reduced values of AH
0.4
0.2
3.3
3.4
3 5 3 6 3.3 3 4
3 5 3 6 3 3 3.4
35
36
I/Absolute Temperature X I 0 3
FIG. 2. Left, panel: Effect of DPC on the oxygen
affinity and temperature sensitivity of stripped human hemoglobin A. Middle and right panels: Temperature-induced changes in the oxygen affinity of
fish whole blood. Note that the in vivo change in P50
in acclimated fish (lines connecting the two temperature curves) is much less than the in vitro temperature sensitivity of blood. (Reprinted from K. Johansen and C. Lenfant, In Alfred Benzon Symposium
IV, Oxygen Affinity of Hemoglobin and Red Cell
Acid-Base Status. Edited by M. Rj?frih and P. Astrup.
Copenhagen, Munksgaard, 1972, with permission of
the publisher.)
Since the intrinsic properties of hemoglobin-oxygen interaction dictate a constant and relatively high AH, observed deviations of the AH of blood from that of
purified hemoglobin solutions must reflect
additive or subtractive, and usually pH dependent, interaction of hemoglobin with
intracellular ligands other than oxygen. Of
particular importance is the effect of organic phosphates on the apparent AH of
oxygen binding. As shown in Figure 2, the
presence of 2,3 DPG reduces the temperature sensitivity of oxygen binding. This
occurs because the binding of oxygen and
2,3 DPG are both exothermic reactions.
Since oxygenation of hemoglobin in the
presence of 2,3 DPG produces displacement of 2,3 DPG, the absorption of heat
from 2,3 DPG displacement is subtracted
from the release of heat from oxygen uptake and the apparent AH is decreased
from -10.7 kcal/mole (no DPG) to - 7 . 3
kcal/mole (DPG). Benesch et al. (1969)
speculated that the low AH of tuna hemoglobin may result from interaction with
some cofactor which is bound with a AH
very close to that of oxygen. If this were
true, then the AH of tuna hemoglobin
should increase when purified solutions instead of hemolysates are examined. To the
author's knowledge, this has not been
done with tuna hemoglobin. However,
Powers et al. (1979) have shown that
species difference in the thermal sensitivity
of oxygen binding by fish blood are due
only to differences in intracellular pH, organic phosphates, and other ligands. They
found no species differences in the intrinsic thermodynamic properties of fish
hemoglobins.
loading at the gills. It would be very interesting to experimentally test this idea. If
the P50 = f (temp) curves intersect in the
physiological range, then, at the temperature of intersection, the fish has only one
operational ODC. At a higher body temperature, the temperature-sensitive hemoglobin would have a lower oxygen affinity
than the temperature-insensitive hemoglobin. However, at a body temperature lower
than the point of intersection of the P50 =
f (temp) curves, the reverse would be true.
Thus, the operational site of both the temperature sensitivity and Bohr effect could
switch between the lungs and tissues at different body temperatures.
The other species in Figure 1 illustrate
the trend of higher apparent AH values in
stenothermal species. For example, the
African lungfish Protopterus experiences
minimal changes in body temperature and
has hemoglobin with a high AH. Conversely, the Australian lungfish, Neoceratodus, is There is, however, some evidence for a
eurythermal and has a low AH. An addi- reduced intrinsic enthalpy of hemoglobin.
tional factor applicable to Protopterus and Barra et al. (1973) showed that one hemoother species capable of bimodal breathing globin component in trout which, even
167
ADAPTATIONS OF RED CELLS TO HYPOXIA AND TEMPERATURE
when purified, has a reduced AH, has a
number of amino acid substitutions involving the loss of histidine. This could provide a molecular mechanism for the reduced AH since the loss of histidines would
reduce the enthalpic contributions of the
Bohr effect to normal temperature sensitivity. The loss of histidines also accounts
for the reduced proton sensitivity of this
trout hemoglobin.
Reduced AH values in reptiles:
A case study
The available data on AH of reptilian
blood does not support the generalization
that stenothermal species show a higher
AH than eurythermal species. In fact, the
reverse seems to be the case (cf., Pough,
1980) when large scale species comparisons are made.
However, for one eurythermal species
which does have a low AH, in vivo data are
available to assess the significance of AH to
oxygen transport. This is the common
iguana in which the AH of whole blood is
- 3 kcal/mole (Wood and Moberly, 1970).
Figure 3 shows the physiological range of
ODCs in the iguana. Blood pH in the iguana, as in most other reptiles, is inversely
related to body temperature. At a body
temperature of 20° the P50 of blood is 20
torr at the in vivo blood pH of 7.7. Body
temperature routinely increases to 37°C
when iguanas bask in the sun. At this temperature, if the AH of iguana blood were
— 13 kcal/mole the P50 of blood would increase to ca. 51 torr due to temperature
alone, i.e., at pH 7.7. However, iguana
blood has an in vivo temperature coefficient of d P H / d T = -0.018 u/°C. So at
37°C, arterial pH would be decreased from
7.7 to 7.4. The Bohr factor of iguana blood
is -0.52 d log P-Jd pH (Wood and Moberly, 1970). This would augment the right
shift of the ODC so that at 37°C and pH
7.4, the P5() of blood would be 73 torr. As
shown in Figure 3, this P50 would be only
7 torr below arterial Po2 and arterial saturation could at best be about 70%. However, when the actual AH of iguana blood
is applied to the above example, the P50 is
found to increase to 54 instead of 73 torr
and arterial blood is almost fully saturated.
1001
90
eo
70
30
40
50
60
70
P02 . mm Hg
90
100
110
Fic. 3. Oxygen dissociation curves of iguana blood
at in vivo values of temperature and pH during heating and cooling. Curves drawn from data of Wood
and Moberly, 1970. Arterial Po2 value from W. R.
Moberly, unpublished.
It could also be argued that the above potential problem would be alleviated by a
reduced Bohr factor. This is true, but may
be a less desirable strategy for a diving animal, like the iguana, in which the large
Bohr factor assures effective utilization of
the blood oxygen store (cf., Wood and
Lenfant, 1976).
Temperature acclimation of oxygen
affinity: Strategy II
A reduced value of AH may be beneficial in reducing the potentially harmful
effects of rapid changes in body temperature or rapid changes in blood temperature in flowing from cool to warm tissues.
For longer term temperature changes,
there are numerous examples where
hemoglobin function shows a type of adaptation analogous to that of metabolic
rate, i.e., a rotation or parallel displacement of the P50 = f (temp) curve. The latter type of acclimation has been described
most often. In this case the seasonal, or
long-term, change in oxygen affinity with
temperature is much less than the acutely
measured AH for either acclimation group
(cf, Figs. 2 and 4). This has been described
for the frog, Rana esculenta (Kirberger,
1953; Straub, 1957; Gahlenbeck and Bartels, 1968), the fishes, Ictalurus nebulosus
(Grigg, 1969), Amia calva (Johansen and
Lenfant, 1972), Carassius auratus (Vaccaro
168
STEPHEN C. WOOD
100
pH 764(
warm
acclim
50
20
30
Temperoture,°C
40
Malacochersus tornicri
10
30
50
70
90
110
Po2 (mmHg)
Fir.. 4. Oxygen dissociation curves of warm and cold acclimated tortoises measured at 20° and 35°C at in vivo
values of blood pH. Insert shows effect of acclimation on reducing the effects of temperature on P5(, (dashed
line). Data from Wood et ai, 1977.
et al., 1975), and a tortoise, Malacochersus
tornieri (Wood et al., 1978).
have, or should have, been investigated:
1. A change in the distribution of multiple
hemoglobin components. This was
ruled out in the cases of Ictalurus and
Carassius.
2. A change in the intracellular (RBC)
concentration of chloride or other diffusible ions known to affect hemoglobin-oxygen affinity, e.g., H + , Mg ++ .
This has not, to my knowledge, been
investigated. However, for species which
show an inverse relationship of blood
Mechanism of temperature acclimation of
pH and temperature, there should be
oxygen affinity
no significant changes in the Donnan
distribution of ions since net protein
The following potential mechanisms of
change
remains constant (Reeves, 1976).
thermal acclimation of oxygen affinity
In all of the above studies, the ODC of
cold acclimated animals was shifted to the
right when compared with that of warm
acclimated animals at the same temperature and pH. Consequently, as shown in
Figures 2 and 4, the AH after thermal acclimation is considerably less than the in
vitro or short-term in vivo AH for these
species.
ADAPTATIONS OF RED CELLS TO HYPOXIA AND TEMPERATURE
ACUTE HYPOXIC HYPOXIA
169
CHRONIC HYPOXIC HYPOXIA
T
T
Increased blood pH
(hyperventilation)
Increased HHb/HbO2 ratio
Altered Donnan distribution
"of H+ ions
Increased red cellpH-
Decreased red cell
Inhibition"^
DPG Phosphtase
p-EFT-SHIFTED ODC |
Activation of DPG
Mutase
jncreased2,3DPG
Concentration
Altered Donnan distribution"
of H+ions
•
I RIGHT-SHIFTED ODCl
Fie. 5. Mechanisms controlling 2,3-DPG metabolism and hemoglobin oxygen affinity of human red blood
cells during hypoxia. (Modified from E. Gerlach and J. Duhm, 2,3-DPG metabolism of red cells: Regulation
and adaptive changes during hypoxia. In Alfred Benzon Symposium IV, Oxygen Affinity of Hemoglobin and
Red Cell Acid-Base Status. Edited by M. Rfinh and P. Astrup. Copenhagen, Munksgaard, 1972, with permission from the publisher.)
3. A change in the concentration or effectiveness of organic phosphate modulators of oxygen affinity. In the study of
Grigg (1969), he ruled out differences
in oxygen affinity due to altered hemoglobin components. Also, since purified
hemoglobins from both acclimation
groups had the same oxygen affinity,
changes in intrinsic oxygen affinity were
excluded. Organic phosphates do not
seem to be involved in the temperature
acclimation of Amia or Carassius but are
known to change during thermal acclimation of other fishes (Powers, 1974).
In the tortoise, an increase in red cell
ATP accounts for the right-shifted
curve of cold acclimated animals.
The physiological significance of this
pattern of temperature acclimation has yet
to be determined. It is, of course, tempting
to speculate that since this pattern of acclimation is analogous to that observed for
oxygen demand, there is some functional
link. The experiment which remains to be
done is to measure oxygen delivery to the
tissues of cold acclimated animals and the
question: is the right-shifted ODC following cold acclimation adaptive to the increase (over acute exposure) in oxygen demand?
ADAPTATIONS TO HYPOXIA
Hypoxia is a frequent or continuous
problem for many ectotherms, especially
aquatic species. The problem is accentuated in water breathers because of the low
oxygen content of water relative to air.
Also, a ventilatory response to hypoxia is
largely precluded because of the excessive
work of breathing.
Adaptations of erythrocyte function to
hypoxia were, until the late 1960s, thought
to be limited to increases in O2 carrying
capacity due to increases in red cell mass.
The demonstration by Benesch and Benesch (1967) and Chanutin and Curnish
(1967) of the allosteric effects of organic
phosphates on human hemoglobin stimulated a great deal of research on this aspect
of metabolism and function in mammalian
red cells (cf., Bunn, 1980). The types of
organic phosphates in vertebrate red
blood cells were described long before the
170
S T E P H E N C.
WOOD
-HYPOXIC HYPOXIAChronic
Acute
Decreased red cell ATP
Increased blood pH
I LEFT-SHIFTED ODCl
Altered Donnan
J
Increased Hb/HbO 2
ratio
Increased red cell pH
Fie. 6. Mechanisms controlling ATP concentration and oxygen affinity of nucleated red blood cells. From
Wood and Lenfant, 1979.
functional significance was appreciated
(Rapoport and Guest, 1941) and current
data on organic phosphate distribution is
presented elsewhere (cf., Bartlett, 1980).
For present purposes, I will consider two
important features of organic phosphates
in ectotherm erythrocytes. First, is the fact
that oxidative phosphorylation is the primary source of most organic phosphates
in the nucleated red cells of non-mammalian vertebrates. Thus, in contrast to 2,3
DPG in mammals, the synthesis of allosteric effectors in nucleated red cells is
oxygen dependent. Second, is the fact that
organic phosphates have, in all red cells,
an indirect (non-allosteric) effect on hemoglobin function. This results from their
effect, as non-diffusible anions, on the
Donnan distribution of hydrogen ions and
intracellular pH. In mammals, as shown in
Figure 5, the initial effect of hypoxia is an
increase in both plasma pH (from hyperventilation) and red cell pH. This stimulates phosphofructokinase which increases
glycolytic rate and DPG mutase which increases 2,3 DPG synthesis. Noteworthy
features of this regulatory pattern are the
negative feedback control of red cell pH
and the fact that the two effects of pH on
Hb-O 2 affinity tend to offset each other.
The Bohr effect tends to move the ODC
to the left during alkalosis while the alkalosis-induced increase in 2,3 DPG tends to
move the ODC to the right. Consequently,
the in vivo curve in acute high altitude exposure may be unchanged from the sea
level curve.
In nucleated red cells (Fig. 6) a decrease
in organic phosphates occurs during hypoxia, at least in the case of ATP. In contrast to mammalian red cells, the acid-base
and organic phosphate changes induced
by hypoxia have complementary effects on
the oxygen affinity of nucleated red cells
(see below). GTP is synthesized in the
Kreb's cycle and its metabolic control may
be independent from ATP production. In
some fish species, GTP has been shown to
be more important than ATP in regulating
Hb-O2 affinity (Weber et al., 1976) and,
although ATP must be reduced during
hypoxic conditions, it seems that GTP may
be regulated enzymatically in a manner
analogous to DPG.
A change in the concentration of organic phosphate has two effects which work in
concert to alter oxygen affinity of hemoglobin. By binding to deoxygenated hemoglobin, the direct or allosteric effect is produced. Also, a change in organic phosphate
concentration affects the Donnan equilibrium of ions (including H+) across the cell
membrane resulting in a Bohr shift of the
ODC. The relative contributions of these
two effects to the displacement of the ODC
depend primarily on the level of plasma
pH. As shown in Figure 7, at high values
of plasma pH, the indirect effect of organic phosphate is more important. In poikilotherms, this is often the physiological
pH range (Duhm, 1971; Wood and Johansen, 1973).
The paradox that both an increase and
a decrease in red cell organic phosphates
ADAPTATIONS OF RED CELLS TO HYPOXIA AND TEMPERATURE
171
IOOI
I
6.6 6.8 7.0 7.2 7.4 7.6 78 8.0
plasmo pH (pHe)
Q
'0
10
20
30
40
Po2 , torr
50
60
70
FIG. 7. Oxygen dissociation curves of control and hypoxia adapted eels at 20° and in vivo values of extracellular and intracellular pH. As shown in the insert, the decreased ATP concentration in hypoxic eels causes
a net efflux of H + ions and a higher intracellular pH than control eels at the same extracellular pH. Data
from Wood and Johansen, 1972 and 19736.
REFERENCES
can be adaptive to hypoxia is resolved
when the degrees of hypoxia experienced Barcroft, J. 1934. Features in the architecture of
physiological function. Cambridge University
by different vertebrates are considered. As
Press.
discussed earlier, it is the degree of hypox- Barcroft,
J. and W. O. R. King. 1909. The effect of
ia which determines the usefulness of a left
temperature on the dissociation curve of blood.
versus a right shift of the ODC. In severe
J. Physiol. (London) 39:374-384.
hypoxia, a left shift proves to be advanta- Barra, D., F. Bossa, J. Bonaventura, and M. Brunori. 1973. Hemoglobin components from trout
geous as shown experimentally in fish and
(Salmo irideus). Determination of the carboxyl
in mice (Wood and Johansen, 1972; Eaton
and amino terminal sequences and their funcetal., 1974).
tional implications. FEBS Lett. 35:151 — 154.
ACKNOWLEDGMENTS
The author's research has been supported by NIH Grant HL-18026 and NSF
Grant PCM-24246. The symposium of
which this article is a part, "Respiratory
Pigments: Structure, Function and Environmental Adaptation," was supported by
NSF Grant PCM78-14511.
Bartlett, G. 1980. Phosphate compounds in vertebrate red blood cells. Amer. Zool. 20:103-114.
Benesch, R. and R. E. Benesch. 1967. The effect of
organic phosphates from the human erythrocyte
on the allosteric properties of hemoglobin. Biochem. Biophys. Res. Commun. 26:162.
Benesch, R. E., R. Benesch, and C. I. Yu. 1969. The
oxygenation of hemoglobin in the presence of
2,3-diphosphoglycerate. Effect of temperature
pH, ionic strength and hemoglobin concentration. Biochemistry 8:2567-2571.
172
STEPHEN C. WOOD
Bunn, H. F. 1980. Regulation of hemoglobin function in mammals. Amer. Zool. 20:199-211.
Carey, F. G. and J. M. Teal. 1966. Heat conservation
in tuna fish muscle. Proc. Nat. Acad. Sci. U.S.A.
56:1464-1469.
Eaton, J. W., T. D. Skelton, and E. Berger. 1974.
Survival at extreme altitude: Positive effect of increased hemoglobin oxygen affinity. Science
183:743-745.
Gahlenbeck, H. and H. Bartels. 1968. Temperatur
adaptation der sauerstoff-affinitat des Blutes von
Rana esculenta. L. Z. Vergl. Physiol. 59:232-240.
Grigg, G. C. 1969. Temperature-induced changes in
the oxygen equilibrium curve of the blood of the
brown bullhead, lclalurus nebulosns. Comp. Biochem. Physiol. 28:1203-1223.
Hashimoto, K., Y. Yamaguchi, and F. Matsuura.
1960. Comparative studies on the two hemoglobins of salmon IV. Oxygen dissociation curve.
Bull. Japan. Soc. Sci. Fish. 26:827.
Hochachka, P. and G. Somero. 1973. Strategies of biochemical adaptation. W. B. Saunders Co., Philadelphia.
Johansen, K., D. Hanson, and C. Lenfant. 1970.
Respiration in a primitive airbreather, Amia calva. Respir. Physiol. 9:162-174.
Johansen, K. and C. Lenfant. 1972. A comparative
approach to the adaptability of O2Hb affinity. In
M. R^rth and P. Astrup (eds.), Oxygen affinity of
librium of hemoglobin from Thunnus thynnus.
Nature 188:895-896.
Rossi-Fanelli, A., E. Antonini, and A. Capu Ho.
1964. Hemoglobin and myoglobin. /n C. B. Anfinsen, Jr., M. L. Anson, J. Edsall, and F. M.
Richards (eds.), Advances in protein chemistry, Vol.
19, pp. 73-222. Academic Press, New York.
Straub, M. 1957. Weitere Untersuchungen zur
Temperatur adaptation der sauerstoff bindung
des blutes von Rana esculenta L. Ztschr. Vergl.
Physiol. 39:507-523.
Taylor, C. R. and C. P. Lyman. 1972. Heat storage
in running antelopes: Independence of brain
and body temperatures. Am. j . Physiol. 222:114117.
Thomson, J. M., J. A. Dempsey, L. W. Chosy, N. T.
Shahidi, and W. G. Reddan. 1974. Oxygen
transport and oxyhemoglobin dissociation during prolonged muscular work. J. Appl. Physiol.
37:658-664.
Weber, R. E., S. C. Wood, and J. P. Lomholt. 1976.
Temperature acclimation and oxygen-binding
properties of blood and multiple hemoglobins of
rainbow trout. J. Exp. Biol. 65:333-345.
Wood, S. C. and Kjell Johansen. 1972. Adaptation
to hypoxia by increased HbO2 affinity and decreased red cell ATP concentration. Nature New
Biology 237:278-279.
Wood, S. C. and Kjell Johansen. 1973a. Blood oxygen transport and acid-base balance in eels durhemoglobin and red cell acid-base status, pp. 750ing hypoxia. Amer. J. Physiol. 225:849-851.
780. Munksgaard, Copenhagen.
Kirberger, C. 1953. Temperatur adaptation der Wood, S. C. and Kjell Johansen. 1973ft. Organic
phosphate metabolism in nucleated red cells: InSauerstoflbindung des Blutes von Rana esculenta
fluence of hypoxia on eel HbO2 affinity. NethL. Ztschr. Vergl. Physiol. 35:153-158.
erlands J. Sea Res. 7:328-338.
Klotz, I. M. and T. A.KIotz. 1955. Oxygen carrying
proteins: A comparison of the oxygenation re- Wood, S. C. and C. Lenfant. 1976. Respiration: Mechanics, control and gas exchange. In C. Gans
action in hemocyanin with that in hemoglobin.
and W. R. Dawson (eds.), Biology of the Reptilia,
Science 121:477-480.
Vol. 5, pp. 225-274. Academic Press, New York.
Pough, F. H. 1980. Blood oxygen transport and delivery in reptiles. Amer. Zool. 20:173—185.
Wood, S. C. and C. Lenfant. 1979. Oxygen transport
and oxygen delivery. In S. C. Wood and C. LenPowers, D. A. 1974. Structure, (unction, and molecfant (eds.), Evolution of respiratory processes: A comular ecology offish hemoglobins. Ann. New York
parative approach, pp. 193-224. Marcel Dekker,
Acad. Sci. 241:472-490.
Inc., New York.
Powers, D. A. 1980. Molecular ecology of teleost fish
hemoglobins: Strategies for adapting to chang- Wood, S. C, G. Lykkeboe, K. Johansen, and R. E.
Weber. 1977. Temperature acclimation in the
ing environments. Amer. Zool. 20:139-162.
pancake tortoise: Metabolic rate, blood pH, oxyRapoport, S. and G. M. Guest. 1941. Distribution of
gen affinity and red cell organic phosphates.
acid-soluble phosphorus in the blood cells of varComp. Biochem. Physiol. 59A: 155-160.
ious vertebrates.}. Biol. Chem. 138:269-282.
Reeves, R. B. 1976. Temperature-induced changes Wood, S. C. and W. R. Moberly. 1970. The influence
of temperature on the respiratory properties of
in blood acid-base status: pH and Pco2 in a biIguana blood. Respiration Physiology 10:20-29.
nary buffer. J. Appl. Physiol. 40:752-761.
Rossi-Fanelli, A. and E. Antonini. 1960. Oxygen equi-