Blood-gas properties of plateau zokor (Myospalax baileyi).

Plateau zokor (Myospalax baileyi) is one of the blind subterranean mole rats that spend their life solely underground in sealed burrows. It is one of the special species of the Qinghai-Tibet plateau. In their burrows, oxygen is low and carbon dioxide is high and their contents fluctuate with the change of seasons, soil types, rain and depth of burrows. However, plateau zokors show successful adaptation to that extreme environment. In this study, their adapting mechanisms to the hypoxic hypercapnic environment were analyzed through the comparison of their blood-gas properties with that of pikas (Ochotona curzniae) and Sprague-Dawley rats. The results indicated that plateau zokors had higher red blood corpuscle counts (8.11+/-0.59 (10(12)/L)) and hemoglobin concentrations (147+/-9.85 g/L), but hematocrit (45.9+/-3.29%) and mean corpuscular volume (56.67+/-2.57 fL) were lower than the other rodents. Their arterial blood and venous blood pH were 7.46+/-0.07 and 7.27+/-0.07. Oxygen pressure in arterial blood of plateau zokors was about 1.5 times higher than that of pikas and rats, and it was 0.36 and 0.26 times in their venous blood. Partial pressure for carbon dioxide in arterial and venous blood of plateau zokors was 1.5-fold and 2.0-fold higher, respectively, than in rats and pikas. Oxygen saturation of plateau zokors was 5.7 and 9.3 times lower in venous blood than that of pikas and rats, respectively. As result, the difference of oxygen saturation in arterial blood to venous blood was 2- and 4.5-fold higher in plateau zokors as that of pikas and rats, respectively. In conclusion, plateau zokors had a high tolerance to pH changes in tissues, together with strong capabilities to obtain oxygen from their hypoxic-hypercapnic environment.