Comparative Study Of Lactate Metabolism Of Plateau Zokor (Myospalax Baileyi) And Plateau Pika(Ochotona Curzoniae)

Plateau pika （Ochotona curzoniae） and plateau zokor （Myospalax baileyi） are thespecialized native species of Qinghai-Tibet plateau, plateau zokor is one of the blindsubterranean mole rats that spend their life solely underground in sealed burrows, andplateau pika is a sprint running animal aboveground. In order to study the differencesof glycolysis in skeletal muscle and lactate metabolism in liver of plateau zokor andplateau pika, we cloned the part of pyruvate carboxylase gene （PC） cDNA sequences;determined the expression levels of PC, Ldh-a, Ldh-b mRNA, the activities of PC,LDH and the contents of lactate; and observed the isoenzymes of LDH in liver andskeletal muscle of plateau pika and plateau zokor, respectively. The results showedthat the expression of Ldh-b increased significantly at mRNA and protein levels （P <0.01）, but the activities and the contents of lactate decreased significantly in skeletalmuscle of plateau zokor compared with that of plateau pika （P <0.01）; in plateauzokor’s liver, the mRNA levels of Ldh-a, Ldh-b and PC, the activities of LDH and PC,and the contents of lactate decreased markedly compared with that of plateau pika （P<0.01）. Interestingly, the main isoenzymes of LDH in the liver of plateau pika wereLDH-B₄, LDH-AB₃, LDH-A₂B₂and LDH-A₃B, but only LDH-A₄was observed in theliver of plateau zokor. These results indicated that plateau pika obtained the most ofATP for sprint running through enhancing the levels of anaerobic glycogysis andproduced more lactate in their skeletal muscle, and the lactate from skeletal musclewas converted into glucose and glucogen in their liver by enhancing the process ofgluconeogenesis. As a result, we supposed that plateau pika reduced dependence onoxygen in hypoxic environment. However, plateau zokor obtained enough ATP fortheir enduring digging activity by enhancing the levels of aerobic oxidation in theirskeletal muscle although they inhabit in hypoxic underground burrows. Thisexperiment will provide scientific theory to further explore plateau animals to adapt tothe low oxygen environment.