The Effect Of Temperature On Blood Gas And Acid-base Status And The Change On The Ultrastructure Of Several Tissues During The Hibernation Period In The Lizard, Phrynocephalus Przewalskii

Temperature is an important factor that affects the animal's metabolism ( especially the ectotherms). In this article, the lizards Phrynocephalus przewalskii that is a representation for transition from ectotherms to endotherms were studied to apprehend the temperature effects on the metabolism in Phrynocephalus przewalskii from two aspects.In the first part, blood gases and acid-base parameters were studied in Phrynocephalus przewalskii, at different temperatures (5℃, 15℃, 25℃, 35℃). The results indicated that increased temperatures were accompanied by a significant reduction of arterial pH from 7.90±0.04 at 5℃ to 7.64±0.06 at 35℃. This fall was associated with an intense increase in Paco₂ from 9.6±0.4mmHg at 5℃ to 15.6±0.9mmHg, whereas arterial PO2 increased significantly with rising temperature from 23.6±l.lmmHg at 5℃to 65.4±2.5mmHg at 35℃.Moreover, arterial [HCO₃^-] changed irregularly with the increased temperature. At low temperatures, the lower PCO2 may reduce the O₂ transport to be adapted to the metabolism depression, and the change of Paco₂also showed that metabolism depression caused the CO₂ production to be reduced. Furthermore, the change of PCO2 was related to the acid-base equilibrium in the body. A higher temperature was accompanied by an elevation of PCO2 that might lead to acidosis. In the experiment, the change of pH in arterial blood confirmed the possibility, but acidosis may be a physical regulation for the higher metabolism. In addition, the comparison of the temperature effects on blood gases and acid-base parameters for O. mykiss, P. scriptaelegans and P._przewalskii indicated that the water-breath vertebrates and air-breath vertebrate regulated the pH in blood by different physical mechanisms.In the second part, comparative observations have been conducted on the ultrastructure of the liver, pancreas and fat body in Phrynocephalus przewalskii during the pre-hibernation and mid-hibernation periods, and the results showed that great changes took place in the cellular structures of glycogen, lipid, endoplasmic reticulum, mitochondrion in the liver, pancreas and fat body of Phrynocephalusprzewalskii. During the mid-hibernation period, dense granular bodies appeared in the mitochondrions of the pancreatic acinar cells, the perinuclear space increase, and the amorphous bodies appeared in the nucleus. These change in morphous and structures might adapt to the metabolism depression and reduce the consumption of materias and energy.