Respiratory characteristics of the blood of the baboon, gibbon and chimpanzee

Hematocrit of mammals (Artiodactyla, Carnivora, Primates) at 1500m and 2100m altitudes

The rise in hematocrit (Hct) is one of the hallmarks of human acclimatization to high altitude and, in chronic conditions, reflects the hypoxia-induced polycythemia. However, it is not a uniform response among domestic species and it is not found in Andean camelids, species long adapted to high altitudes. Hence, we asked to what extent the polycythemia of humans is common among mammals. Hct data were collected from captive mammals of three orders (Primates, Artiodactyla, Carnivora), 70 specimens of 33 species at ∼1500m altitude (barometric pressure Pb=635mmHg) and 296 specimens of 64 species at ∼2100m (Pb=596mmHg), long-term residents at those altitudes. Sea level values and data in men and women at the corresponding altitudes were from a compilation of literature sources. At either altitude Hct was significantly higher than at sea level both in men and women; the increase (ΔHct) for genders combined averaged 3.4% (±0.7 SEM) at 1500m and 5.4% (±0.3) at 2100m. Differently, among the three mammalian orders studied a significant increase in Hct occurred only in females of Carnivora (at 1500m) and in males of Primates (at 2100m). The average ΔHct of all species combined was 0.8% (±0.7) at 1500m and 1.5% (±0.4) at 2100m, both significantly less than in humans (P<0.001). At 2100m the average ΔHct of nine species long adapted to high altitude was 0.4% (±1), significantly less than in non-adapted species (P<0.001). A polycythemic response like that of men and women at 2100m occurred in less than 10% of the mammals examined. We conclude that, at least for the altitudes studied, a minimal polycythemia is a general feature of both high-altitude adapted and non-adapted species, and the magnitude of the human response is exceptional among mammals.

Hematocrit and Hemoglobin Levels of Nonhuman Apes at Moderate Altitudes: A Comparison with Humans

Mortola, Jacopo P. and DeeAnn Wilfong. Hematocrit and hemoglobin levels of nonhuman apes at moderate altitudes: a comparison with humans. High Alt Med Biol. 17:323-335, 2016.-We asked to what extent the hematologic response (increase in hematocrit [Hct] and in blood hemoglobin concentration [Hb]) of humans to altitude hypoxia was shared by our closest relatives, the nonhuman apes. Data were collected from 29 specimens of 7 species of apes at 2073 m altitude (barometric pressure Pb = 598 mm Hg); additional data originated from apes located at a lower altitude (1493 m, Pb = 639 mm Hg). The human altitude profiles of Hct and Hb between sea level and 3000 m were constructed from a compilation of literature sources that (all combined) comprised data sets of 10,000-12,000 subjects for each gender. These human data were binned for 0-250 m altitude (sea level) and for each 500 m of progressively higher altitudes. Values of Hb and Hct of both men and women were significantly higher than at sea level at the 1500 bin (1250-1750 m); hence, the altitude threshold for the human hematological responses must be between 1000 and 1500 m. In the nonhuman apes, no increase in Hct or Hb was apparent at 1500 m; at 2000 m, the increase was significant only for the Hb of females. At either altitude in the group of nonhuman apes, the increase in Hct was much less than in humans, and that of Hb was significantly less at 1500 m. We conclude that lack of, or minimal, hematopoietic response to moderate altitude can occur in mammalian species that are not genetically adapted to high altitudes. Polycythemia is not a common response to altitude hypoxia and, at least at moderate altitudes, the degree of the human response may represent the exception among apes rather than the rule.

Comparative studies of the respiratory functions of mammalian blood. XII. Black galago (Galago crassicaudatus argentatus) and brown galago (Galago crassicaudatus crassicaudatus)

Respiratory characteristics of blood from sixteen adult male galagos were studied (8 brown and 8 black). The average body weight of the black galagos was significantly higher than that of the brown(1.512 +/- 0.162 vs. 0.988 +/- 0.099 kg, respectively). The blood oxygen capacities for black and brown galagos were 20.6 +/- 1.9 and 21.5 +/- 1.8 vol percent, respectively. The Bohr factor for blood from the black galago was -0550 +/- 0.039 (n = 9) and for brown galago blood was -0.523 +/- 0.050 (n = 6). There was no significant (P greater than 0.05) difference in P50 values of blood from the two subspecies of galagos, 36.7 +/- 1.1 vs. 37.7 +/- 0.9 mm Hg for the black and brown, respectively. The Haldane effect for black galago blood was higher than that for brown (7.5 vs. 65 vol percent, respectively). The concentrations of 2.3-DPG were similar in black and brown galago blood, 16.16 +/- 1.52 vs. 16.37 +/- 0.76 mumol/g Hb, respectively. Starch gel electrophoresis showed three major components of hemoglobin from both subspecies. There is a trend toward decreasing blood oxygen affinity as one ascends the primate evolutionary scale, which may be secondary to the trend toward a greater adult body weight.

The phylogenetic distribution of red cell 2,3 diphosphoglycerate and its interaction with mammalian hemoglobins

In order to better understand the extent to which 2,3 diphosphoglycerate (DPG) contributes to red cell function in the mammals, we assayed DPG levels in blood from a taxonomically diverse set of 71 species representing 14 orders. In addition, for 66 species and 4 hemoglobin phenotypes of the sheep, the effect of DPG on oxygen affinity was measured by determining P 50 values for hemoglobin in the absence of DPG and at 0.2 mM and 1.0 mM concentrations. Most mammals had high levels of red cell DPG and phosphate-free hemoglobins with a relatively high oxygen affinity. In contrast, two taxonomically unrelated groups had both very low intra-erythrocytic DPG concentrations as well as hemoglobins of native low oxygen affinity that interacted weakly with DPG. This latter group includes the Feloidea (order Carnivora) and the Bovoidea (order Artiodactyla). The relationship between DPG concentration, hemoglobin oxygen affinity and the interaction of DPG with hemoglobin is treated quantitatively to provide a model of mammalian red cell function. This derived expression is compared with descriptive allometric equations for whole blood P 50 and is shown to provide statistically reasonable predictions.