2 - Use of Genetic Anaemias in Mice as Tools for Haematological Research

Abstract

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 ∼1500 m altitude (barometric pressure Pb = 635 mm Hg) and 296 specimens of 64 species at ∼2100 m (Pb = 596 mm Hg), 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 1500 m and 5.4% (± 0.3) at 2100 m. Differently, among the three mammalian orders studied a significant increase in Hct occurred only in females of Carnivora (at 1500 m) and in males of Primates (at 2100 m). The average ΔHct of all species combined was 0.8% (± 0.7) at 1500 m and 1.5% (± 0.4) at 2100 m, both significantly less than in humans (P < 0.001). At 2100 m 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 2100 m 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.