Whole Blood Oxygen Affinity Research Articles

The Blood of Carnivorous Marsupials: Low Hemoglobin Oxygen Affinity

We examined the blood of four dasyurid marsupials, all small, active insectivores and/or carnivores, to establish if there were any specializations in oxygen transport. All four species had hemoglobins with a low affinity for oxygen. This was demonstrated by high P50's (the partialpressure of oxygen [PO₂] at which the hemoglobin is half-saturated with oxygen) of the whole blood (means of 38.3-59.8 mmHg) and of red cells suspended in a physiological buffer (means of 41.6-49.0 mmHg) at a CO₂ tension of 43 mmHg. There was a strong correlation betuween increase in body mass over three orders of magnitude and increase in the oxygen affinity of the whole blood. The effects of changing CO₂ tensions on the oxygen affinity of whole blood were measured as △log P50/Δlog PCO₂; mean values ranged from 0.25 to 0.373. Values for △log P50/ΔpH wuere measured for red-cell suspensions; means values ranged from -0.40 to -0.481. The introduction of 2,3-diphosphoglycerate significantly decreased the oxygen affinity, of the hemoglobin of Dasyuroides byrnei. The blood of D. byrnei and Dasyurus viverrinus had high hematocrits and high concentrations of hemoglobin. We conclude that hemoglobins with a low affinity for oxygen, an adaptation to an active lifestyle, are a characteristic of dasyurid marsupials generally.

Allosteric Control of Oxygen Binding by Haemoglobin During Embryonic Development in the Crocodile Crocodylus Porosus: The Role of Red Cell Organic Phosphates and Carbon Dioxide

ABSTRACT The P50 of whole blood [30°C, (15.6mmHg)] decreases during embryonic development from approximately 6.7kPa (50mmHg) at 15 days to about half this value at hatching (86 days), paralleling a decrease in ATP from 100 to 5–10 μmol g−1 Hb. There is also a progressive changeover from embryonic to adult haemoglobin (HbA). A pulse of 2,3-diphosphoglycerate (2,3-DPG) (18μmol g−1 Hb) occurs late in embryonic life. It has no effect on whole-blood oxygen-affinity and falls rapidly at hatching to values typical of post-hatchling crocodilians in general (<1.0 μmol g−1 Hb). ATP has a marked effect on the oxygen affinity of embryonic haemoglobin (HbE) but not on HbA. 2,3-DPG has only very small effects on the oxygen affinities of HbE and HbA. CO2 has a small effect on the oxygen affinity of HbE but a marked effect on that of HbA. Values of measured in the chorio-allantoic artery [2.9kPa (22mmHg)] and vein [5.9kPa (52mmHg)] imply an increase in saturation from approximately 30% to more than 80%. Neither whole-blood oxygen-affinity nor ATP level was altered in response to an experimental 7-day exposure to low ambient oxygen levels [10.7kPa (80mmHg)]. The results do not lend themselves easily to the pan-selectionist paradigm in which all physiological traits are viewed as being adaptive.

Reliability of the determination of whole-blood oxygen affinity by means of blood-gas analyzers and multi-wavelength oximeters.

Determination of the oxygen affinity of human whole blood with the help of blood-gas analyzers and multi-wavelength oximeters is compared with an accurate method for recording hemoglobin oxygen dissociation curves (Clin Chem 1982;28:1287-92). P50 (oxygen tension at half saturation; So2 = 50%) and Hill's n (delta log [So2/(1-So2)]/delta log Po2) were determined in blood of 24 healthy donors. Three slightly different procedures were used for determination of P50 on the basis of Po2, pH, Pco2, and So2 measured with each of four different blood-gas analyzer/oximeter combinations. These methods were not able to discriminate between high and low values for P50 within the normal reference interval, but never failed to detect the high oxygen affinity of blood stored for 12 days, reflected in low values of P50. The methods thus proved suitable for detecting clinically significant deviations in oxygen affinity such as occur in patients with, e.g., abnormal hemoglobins, anemias, or carbon monoxide poisoning. Determination of Hill's n by these methods did not produce useful results.

Hypoxic Responses in a Fish From a Stable Environment: Blood Oxygen Transport in the Antarctic Fish Pagothenia Borchgrevinki

ABSTRACT The effects of hypoxic exposure on whole-blood oxygen-affinity were examined in the antarctic fish Pagothenia borchgrevinki. Fish exposed to for 11–14 days at −1·5°C had a P50 value of 20·6 ± 4·8 mmHg (S.D., N =13) at pH8-16, compared with 31·1 ± 4·3mmHg (N = 10) at pH8-00 for normoxic fish. Exposure to low oxygen levels resulted in a significant (66 %) rise in haemoglobin concentration, and erythrocyte [ATP] decreased by approximately 27%. There was no evidence for erythrocyte swelling. An aberrant gill morphology was observed in six fish and these showed unexpectedly high erythrocyte ATP levels. Oxygen-carrying capacity increased by approximately 40% in hypoxic fish and was correlated with a 34 % decrease in spleen mass. Despite the fact that antarctic fish have exceptionally low demands for oxygen and are unlikely ever to encounter environmental hypoxia, this antarctic fish has the necessary machinery to respond to hypoxia in a way that is typical of teleosts that naturally inhabit oxylabile environments. The ability to make short-term adaptive changes in the O2 delivery system in response to hypoxic exposure may be typical for vertebrates in general, rather than a feature seen only in those organisms which encounter environmental hypoxia on a regular basis.

Pathophysiology of hypoxia in mice infected with Plasmodium berghei.

Pathophysiological significance of hypoxia in malarial infection was investigated in mice infected with Plasmodium berghei NK65. Intraperitoneal inoculation of mice with 1 X 10(7) parasitized red blood cells resulted in death of the hosts 6-7 days later. Anaemia of infected animals developed on day 4 after inoculation and oxygen affinity of whole blood, measured as P50 act pH, increased simultaneously. This change may be a physiological adaptive response to a reduction in oxygen delivery to the tissues to day 5. However, the blood oxygen supply on day 6 appeared to be deteriorating and this is thought to be an important factor contributing to the death of the host. The value of adenylate energy charge in red cells during malarial infection, however, was comparatively well-maintained. Allopurinol stimulated the multiplication of malaria parasites and seems to have induced collapse in host-parasite balance more rapidly. Decrease in blood pH and in blood oxygen transport may be important factors for the pathogenesis of the allopurinol-treated hosts.

Pressure increases oxygen affinity of whole blood and erythrocyte suspensions.

Effect of hydrostatic pressure (HP) on whole blood (WB) or erythrocyte suspension hemoglobin (Hb) O2 affinity has been studied using newly developed techniques. O2 partial pressure at which hemoglobin is half-saturated with O2 (P50) measurements were made at 5 HP (1, 26, 51, 76, and 126 ATA) on thin films of human WB or erythrocytes at 37 degrees C. CO2 partial pressure of WB was either 28 or 57 Torr (film pH 7.51 or 7.31). HP increased affinity of erythrocytes and WB. For erythrocytes in tris(hydroxymethyl)aminomethane buffer, the ratio (r) of P50 (1 ATA)/P50 (51 ATA) was 1.089 (P less than 0.01) at pH 7.0. WB P50 decreased with HP at a rate of -3.3 X 10(-2) Torr X atm-1; change in P50 at higher HP vs. 1 ATA was highly significant (P less than 0.01). No effect of HP was seen on the CO2 Bohr coefficient. Inert gas choice, N2 vs. helium (He), had no effect. Measurement of decrease of P50 with HP at 76 ATA in hemolyzed WB gave an r of 1.15, as great or greater than that found in WB, indicates that Donnan equilibrium alteration is not involved. No effect of HP was found in WB on the ratio of P50 of erythrocytes with normal (5 mmol/l erythrocytes) 2,3-diphosphoglycerate (DPG) to P50 of erythrocytes with less than 5% of normal DPG; i.e., no effect of pressure was seen on the independent influence of DPG on P50. WB measurements of Hb O2 uptake under simulated physiological conditions are characterized by a net decrease in partial molal volume on oxygenation of 30-35 ml/mol Hb4.

EFFECT OF BW12C ON OXYGEN AFFINITY OF HAEMOGLOBIN IN SICKLE-CELL DISEASE

Eight subjects with sickle-cell disease in the symptom-free steady-state received a single one-hour infusion of the new anti-sickling agent BW12C on a total of eleven occasions. A dose-dependent increase in wholeblood oxygen affinity was observed, resulting from the action of BW12C in stabilising the oxy-conformation of haemoglobin and causing a left shift of the oxygen saturation curve. At the highest dose given (20 mg/kg bodyweight), up to 23% of haemoglobin was modified to a BW12C-reacted high-affinity form without evidence of tissue hypoxia. There was biochemical and rheological evidence for a transient decrease in haemolytic rate.

Blood respiratory properties of the mudsucker fish Labeo capensis (Smith)

1. 1. For Labeo capensis (Smith) the increase in blood organic phosphates (ATP, GTP) in winter fish exceeds the increase in summer fish. 2. 2. Blood chlorides, blood osmotic pressure, hematocrit and hemoglobin concentration decrease significantly in winter fish when compared to summer fish. 3. 3. Four effectors, viz. temperature, organic phosphates, H + and Cl −, could lower the oxygen affinity of whole blood, especially in summer fish. .

The oxygen uptake of Sarotherodon niloticus L. and the oxygen binding properties of its blood and hemolysate (pisces: cichlidae)

1. 1. The oxygen consumption of Sarotherodon niloticus L. was found to decline below a critical oxygen concentration of about 2 mg O 2/l. 2. 2. An important influence of CO 2 on the oxygen affinity of whole blood was observed at all temperatures between 20 and 35°C for gas mixtures containing 5.6% CO 2. 3. 3. Purified hemolysate showed extremely high oxygen affinities ( p 50=1.08 mmHg at pH 8.2 and 20°C). Low cooperativity was observed at all temperatures from 20 to 35°C, and pH values between 6.5 and 8.2. 4. 4. The Bohr effect proved to be important at pH values lower than pH 7.5 ( Φ = Δ log P 50/ ΔpH = −0.58 between pH 6.5 and 7.0 at 35°C). 5. 5. The oxygen affinities show high thermal sensitivity without a marked pH influence (Δ H value for overall oxygenation at pH was −71.7kJ/mol). 6. 6. The obtained results are interpreted as adaptations to diurnal variations in ambient temperature and oxygen availability.

Human whole-blood oxygen affinity: effect of temperature.

phe effect of temperature changes on human whole-blood O2 affinity was measured in the blood of six healthy donors over almost the entire O2 saturation (SO2) range (1-99%). The results showed that temperature has no influence on the shape of the O2 dissociation curve, implying that the temperature coefficient (delta log PO2/delta T) is independent of SO2. Simultaneous measurements of the total (proton) Haldane factor (delta[HbH]/[delta HbO2]) at the five temperatures under study (22, 27, 32, 37, and 42 degrees C) revealed that this factor depends on temperature. The liberation of protons from hemoglobin appeared to be linear with respect to changes in SO2. We therefore conclude that the (proton) Bohr factor (H+ factor) is dependent on temperature over the entire SO2 range in the same way as previously described for SO2 = 50%. The exothermic oxygenation reaction in whole blood was accompanied by a heat evolution (delta HO2) of 42.7 kJ/mol (monomeric) hemoglobin.

Human whole-blood oxygen affinity: effect of carbon monoxide.

Oxygen dissociation curves (ODC) were recorded in the presence of carboxyhemoglobin fractions (FHbCO) up to 60%. The gradual shift to the left of the ODC at increasing amounts of HbCO was reflected in a gradual fall in the half-saturation pressure of the remaining Hb and was accompanied by a gradual change in the shape of the ODC to a hyperbolic one. The H+ factor (delta log PO2/delta pH) was determined over the entire oxygen saturation (SO2) range at three different FHbCO levels (14, 30, and 52%). At FHbCO = 14 and 30% and for the SO2 range 20-90%, the H+ factor vs. SO2 curve was not significantly different from that in the absence of HbCO. At FHbCO = 52%, however, the value found for the H+ factor (-0.55) was appreciably more negative than in the case of blood containing less than 1% HbCO (-0.44), and there was no dependence on SO2. Comparison of measured and calculated ODCs at varying HbCO fractions showed, for FHbCO less than or equal to 50%, that measured and calculated ODCs coincide over the greater part of the SO2 range. For FHbCO greater than 50%, the measured ODC was situated to the left of the calculated one over the entire SO2 range. We conclude that the heme-heme interaction for CO is appreciably larger than for O2 only for FHbCO greater than 50%, whereas for FHbCO less than 50% there is virtually no difference.

Glycosylated haemoglobins and the oxygen affinity of whole blood.

The pO2 at which haemoglobin is half-saturated with oxygen (p50) was determined at fixed pCO2 (45 mmHg) and without altering the resulting pH and the level of organic phosphates in heparinized whole blood samples from 26 diabetic patients and 24 normal subjects of both sexes. Diabetic blood p50 was higher (29.79 +/- 1.68 versus 28.26 +/- 1.16 mmHg, p less than 0.001) and with a higher 2,3-diphosphoglyceric acid/haemoglobin molar ratio (1.04 +/- 0.15 versus 0.86 +/- 0.10, p less than 0.001). The pH at a pCO2 of 45 mmHg was the same in the two groups. The observed p50 values were compared with those obtained after normalization in respect to pH and the level of 2,3-diphosphoglyceric acid. We conclude that glycosylated haemoglobins, known to have an increased affinity for oxygen when purified and in diluted solutions, do not play a significant role in the oxygen affinity pattern of diabetics at the concentrations normally found in vivo.

Regulation of Blood Oxygen Affinity in the Australian Blackfish Gadopsis Marmoratus

ABSTRACT The regulation of whole blood oxygen affinity in the freshwater black-fish Gadopsis marmoratus Richardson has been examined, and correlations made between oxygen-binding properties and the habitat and swimming behaviour of the fish. Blackfish whole blood has a low oxygen affinity relative to other fish bloods reported in the literature. This is not due to a low oxygen affinity of the stripped haemoglobins, but arises from interactions between haemoglobin and intraerythrocytic modulators. The presence of high concentrations of ATP, and to a lesser extent GTP, in the erythrocyte, together with the effect of these nucleoside triphosphates on the oxygen affinity of haemoglobin solutions at physiological NTP: Hb4 molar ratios, demonstrates that this class of compounds is a major regulator of oxygen affinity in blackfish blood. The oxygen affinities of whole blood and haemoglobin solutions are sensitive to pH, with haemoglobin solutions displaying a relatively large alkaline Bohr coefficient of-– 1·05 over the physiologically relevant pH range of 6·5–7·0. Although increasing lowers the oxygen affinity of whole blood, it does so only through the effect on pH, as pH-buffered haemoglobin solutions show no oxygen-linked CO2 binding. This lack of oxygen-linked CO 2 binding has not been reported for any other naturally occurring vertebrate haemoglobins. Muscle morphology and biochemistry, and behavioural observations, indicate that the blackfish uses anaerobic energy metabolism during rapid swimming and in recovery. It is concluded that the oxygen-binding properties of blackfish blood reflect adaptations for maintaining adequate tissue oxygenation for animals at rest and during slow sustained swimming in waters of high oxygen tensions.

An Increased Bohr Effect in Sickle Cell Anemia

AbstractRecent findings that hemoglobin S gelation and sickling are pH- dependent and also influence oxygen affinity suggested that the red cells containing this hemoglobin variant might show an abnormal Bohr effect. We therefore studied the effects of pH variation on the in vitro oxygen affinity of whole blood from persons with sickle cell anemia (SS) and normal donors (at 37 degrees C and constant carbon dioxide tension of 40 mm Hg). The Bohr effect in SS blood was greatly increased only between blood pH 7.4 and 7.2 (cell pH 7.2 and 7.0, a shift that strongly affects gelation), with delta log p50/deltapH= - 0.92 to -0.99 (normal = -0.42 to -0.46). Thus a drop in SS blood pH below 7.4 in tissue capillaries yields twice the normal decrease in oxygen affinity and a large release of oxygen from red cells, whose risk of sickling is high. Even mild transient acidosis would seem hazardous for patients with sickling disorders.

An increased Bohr effect in sickle cell anemia

Recent findings that hemoglobin S gelation and sickling are pH- dependent and also influence oxygen affinity suggested that the red cells containing this hemoglobin variant might show an abnormal Bohr effect. We therefore studied the effects of pH variation on the in vitro oxygen affinity of whole blood from persons with sickle cell anemia (SS) and normal donors (at 37 degrees C and constant carbon dioxide tension of 40 mm Hg). The Bohr effect in SS blood was greatly increased only between blood pH 7.4 and 7.2 (cell pH 7.2 and 7.0, a shift that strongly affects gelation), with delta log p50/deltapH= - 0.92 to -0.99 (normal = -0.42 to -0.46). Thus a drop in SS blood pH below 7.4 in tissue capillaries yields twice the normal decrease in oxygen affinity and a large release of oxygen from red cells, whose risk of sickling is high. Even mild transient acidosis would seem hazardous for patients with sickling disorders.

Effects of some cardioactive drugs on the oxygen affinity of whole blood.

Increasing amounts of Digoxin, Lasix, Teofyllamin and CI-775 were added to human blood in vitro and the whole blood oxygen affinity was measured. We found no definite proof that any of the drugs was able to affect the oxygen affinity of the red cells even at unphysiologically high concentrations.

Relationship between the major phosphorylated metabolic intermediates and oxygen affinity of whole blood in the loggerhead ( Caretta caretta) and the green sea turtle ( Chelonia mydas) during development

(1) 2,3-Diphosphoglyceric acid (2,3-DPG) is present in the erythrocytes (RBC) of the 68-day loggerhead turtle embryo and 44-day green sea turtle embryo at levels of 7.4 and 5.5 μmoles/ml of RBC, representing the major organic phosphate during the latter period of embryonic development. (2) Inositol pentaphosphate (IPP) is absent in the red blood cells of the embryos of both the loggerhead and green sea turtle. (3) Near equimolar amounts of 2,3-DPG and IPP are present in the erythrocytes of the adult loggerhead and green sea turtle. The total concentration of these two organic phosphates is approximately 0.75 μmoles/ml of RBC in the adult of both species. (4) There is a switch from embryonic to adult hemoglobin during development of these two species of turtles; the two embryonic bands have identical electrophoretic mobilities, whereas the two adult bands migrate differently on cellulose acetate at pH 8.6. (5) The whole blood oxygen affinity of the adult loggerhead and green sea turtle is 60.3 and 32.6 Torr, respectively. (6) The stripped adult hemoglobins in these two species of turtles show no change in oxygen affinity upon addition of 2,3-DPG, ATP, or IPP. (7) It therefore appears unlikely that whole blood oxygen affinity is controlled by organic phosphate modulation of hemoglobin function in these species of turtles.

Oxygen-binding properties of hemoglobins from estivating and active African lungfish.

The oxygen-binding characteristics and the multiplicity of the stripped hemoglobiin from active lungfish Protopterus amphibius, are the same as in specimens that have been estivating for about 30 months, showing that alteration in the hemoglobin molecules is not involved in the earlier reported increase in oxygen affinity of whole blood during estivation (Johansen et al., '76). At pH 7.0 and 26 degrees C the hemolysates show a high oxygen affinity (P50 = 3.1 Torr), a Bohr factor (delta log P50/delta pH) of - 0.33, and a cooperativity coefficient (n) of 1.7. Between 15 and 26 degrees C, the apparent heat of oxygenation (delta H) is - 8.6 Kcal-mole-1 at pH 7.0, corresponding with data for other fish. A low sensitivity of oxygen affinity to urea appears to be adaptive to the high urea concentrations in estivating lungfish. The salt sensitivity is, however, similar to human hemoglobin. The hemoglobin consists of two major (electrophoretically anodal) components, which differ slightly in oxygen affinity but are both sensitive to pH and nucleoside triphosphates (NTP). Guanosine triphosphate (GTP), the major erythrocytic organic phosphate, however, depresses the oxygen affinity of the composite and separated hemoglobins more effectively than ATP suggesting that GTP is the primary modulator of oxygen affinity. Comparative measurements reveal only one major hemoglobin component in P. annectens which has a markedly lower oxygen affinity and phosphate sensitivity than P. amphibius hemoglobins and thus seems less pliable to phosphate-mediated variation in oxygen affinity. The data are discussed in relation to the hemoglobin systems of other fish.

The relationship of blood oxygen affinity to body size in lizards

1. 1. Oxygen affinity of whole blood of 51 species of lizards from 12 families was measured at the eccritic temperature of each species. 2. 2. Blood oxygen affinity was lower than that of birds or mammals and increased with increasing body size. 3. 3. Iguanid lizards were used as a basis for comparisons of other families. Blood oxygen affinity of lizards in the families Agamidae, Cordylidae, Lacertidae and Varanidae did not differ from that of iguanids of comparable body size. 4. 4. Teiid and anguid lizards had lower oxygen affinities than iguanids. possibly reflecting their more active lives. 5. 5. Scincid and chamaeleonid lizards had higher blood oxygen affinities than iguanids, apparently as a result of their lower eccritic temperatures. 6. 6. Geckonid and xantusiid lizards had higher blood oxygen affinities than iguanids at their normally low eccritic temperatures and at higher temperatures comparable to eccritic temperatures of iguanid lizards.

The oxygen affinity of concentrated human hemoglobin solutions and human blood.

The log P50 of normal human blood at 37 degrees C, PCO2 = 0, 21, 42, AND 57 MM Hg in the absence and in the presence of 2,3-DPG and ATP, has been determined in the pH range 7.0 to 7.6. Similar data have been obtained for human hemoglobin isotonic solutions at different protein concentrations in the presence of various amounts of each of the cofactors which are known to affect hemoglobin oxygen affinity in blood. It has been found that the addition of KC1, organic phosphates, magnesium ions, and CO2 confers to a 32% human hemoglobin solution the same oxygen affinity (over the entire physiological pH range) of whole blood. Thus there is no room for significant effects caused by some other unidentified molecules or ions.