Expression of Ldh-c (Sperm-Specific Lactate Dehydrogenase Gene) in Skeletal Muscle of Plateau Pika, Ochotona curzoniae, and its Effect on Anaerobic Glycolysis

The plateau pika (Ochotona curzoniae) has a strong adaptability to hypoxic plateau environment. We found that the sperm-specific lactate dehydrogenase (LDH-C-4) gene Ldh-c is expressed in plateau pika skeletal muscles. In order to shed light on the effect of LDH-C-4 on the anaerobic glycolysis in plateau pika skeletal muscle, 20 pikas were randomly divided into two groups the inhibitor group (experimental) and the control group, reach of 10 pikas. The pikas of experimental group were injected with 1 mL of 1 mon N-isopropyl oxamate, a specific LDH-C-4 inhibitor, in biceps femoris muscle of hind legs, each leg with 500 mu L. The pikas of control group were injected with the same volume of normal saline. The mRNA and protein expression levels of Ldh-c in plateau pika skeletal muscles were determined by real-time PCR and Western blot. The LDH activities, lactate contents and ATP levels in skeletal muscle were compared between the experimental group and the control group. The results showed that 1) the expression levels of Ldh-c mRNA and protein were 0.804 +/- 0.059 and 0.979 +/- 0.176, respectively; 2) 30 min after administration of 1 mL of 1 mol/L N-isopropyl oxamate injected in biceps femoris muscle, the concentration of N-isopropyl oxamate in blood was 0.08 mmol/L; 3) in skeletal muscles of the inhibitor group and the control group, the LDH activities were 6.30 +/- 0.50 U/mg and 10.01 +/- 0.59 U/mg, the contents of LD were 0.28 +/- 0.039 mmol/g and 0.84 +/- 0.16 mmol/g, and the ATP level were 8.15 +/- 1.03 nmol/mg and 12.06 +/- 1.23 nmol/mg (P < 0.01); 5) the inhibition rates of N-isopropyl oxamate to LDH, LD and ATP were 37.12%, 66.27%, and 32.42%, respectively. The results suggest that Ldh-c expresses in skeletal muscles of plateau pika, and the pika skeletal muscle may get at least 32.42% ATP for its activities by LDH-C-4, catalyzed anaerobic glycolysis, which reduces the dependence on oxygen and enhances the adaptation to the hypoxic environments.