Seasonal Changes In Physiological Parameters Related To Adaptation To Hypoxia In Plateau Zokors

Plateau zokors (Myospalax baileyi) are one of blind subterranean mole rats that spend their life solely underground in sealed burrows. In their burrows, oxygen is low and carbon dioxide is high and their contents fluctuated with changing of seasons, types of soil, water in soil and depth of burrows. To explore the mechanisms of plateau zokors to adapt the hypoxic-hypercapnic environment, its blood physiological parameters and the content of myoglobin in cardiac and skeletal muscle were analyzed in spring, summer and autumn. The activities of lactate dehydrogenase in serum and tissues, and the content of lactate in serum of plateau zokors in spring, summer and autumn were determined by using method of enzyme analysis. The seasonal changes of lactate dehydrogenase isoenzymes spectrums in serum and tissues of plateau zokors were analyzed by using method of the discontinuous systemic poly-acrylamide perpendicular plank gel electrophoresis.The results indicated that red blood corpuscle (RBC), hemoglobin (Hb) and hematocrit (HCT) in blood of plateau zokors significantly increased from spring to autumn. The activity of inducible nitric oxide synthase (iNOS) and carbon dioxide combining-power (CO2-CP) in serum of plateau zokors were increased markedly with increase of carbon dioxide concentration in burrows in summer. Arterial blood pH of plateau zokors in spring, summer and autumn had no obvious difference, but pH of venous blood in spring significantly lower than that in summer and autumn. Partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2) and difference of partial pressure of oxygen (DPO) between arterial blood and venous blood were without obvious seasonal difference. Degree of oxygen saturation of arterial blood (SaO2) had no obvious seasonal difference in spring, summer and autumn, but SO2 of venous blood in spring significantly lower than that in summer and autumn. In cardiac muscle and skeletal muscle of plateau zokors, the content of myoglobin (Mb) was increased obviously in spring. The content of 2, 3-diphosphoglycerate (2, 3-DPG) in erythrocyte of plateau zokor was increased obviously in autumn. The activities of lactate dehydrogenase (LDH) in serum had obvious seasonally difference that they were higher in spring and lower in autumn, and the content of lactate in serum showed same changing tendancy. The spectrums of lactate dehydrogenase isoenzymes in serum showed five bands that were LDH1, LDH2, LDH3, LDH4 and LDH5 from positive pole to negative pole respectively in spring, it showed clearly two bands in serum of summer that were LDH4 and LDH5 and one band in serum of autumn that was LDH5. The activities of LDH in tissues of skeletal muscle, cardiac muscle and brain were higher compared with the other tissues, it decreased markedly from spring to autumn. In tissues of liver, kidney and lungs, activities of LDH were lower than the other tissues. In livers, activities of LDH in spring were significantly higher than that in summer and autumn, which had no obvious difference between summer and autumn. In kidneys and lungs, activities of LDH showed no obviously difference between spring and summer, which decreased markedly in autumn. The spectrums of lactate dehydrogenase isoenzymes in tissues of cardiac muscle, liver, lungs, kidney, brain and skeleton muscle showed five bands in spring, summer and autumn respectively, the spectrums were obviously different in different tissues, and the content of LDH isoenzymes showed seasonal changes in different tissues.In conclusion, with seasonal fluctuation of oxygen and carbon dioxide in burrows , physiological parameter of oxygen metabolism of plateau zokors showed seasonal changes. Glycolysis levels in plateau zokors had obvious seasonally change which decreased from spring to autumn significantly. It related to the activity of plateau zokors in different seasons and seasonal fluctuation of oxygen and carbon dioxide in burrows of plateau zokors. The partial pressure of carbon dioxide in arterial blood of plateau zokors increased significantly, PO2 and SaO2 of arterial blood were high, but PO2 and SO2 of venous blood were low in the three seasons. DPO between arterial blood and venous blood were high that were advantageous to obtaining oxygen in tissues effectively. The number of RBC and the contents of Hb were higher while the blood viscosity was not increased. The contents of 2, 3-DPG in erythrocyte of plateau zokors was low, and the contents of Mb were high.Not only were they advantageous to the blood combination and transportation more oxygen in the lung, and release enough oxygen in tissues, but also they were advantageous to obtaining oxygen in tissues effectively. Oxygen is low and carbon dioxide is high and their concentrations fluctuate with the change of seasons in burrows, plateau zokors enhanced capabilities of getting oxygen by regulated the contents of functional proteins related to transport oxygen and the physiological mechanisms related to metabolisms of oxygen so as to maintain oxygen homeostasis of their tissues.