Sex-linked differences in activity of enzymes in the blood of the urodele amphibian Pleurodeles waltl.

Few data are available on enzyme activity in amphibian plasma or erythrocytes. We measured the activity of several blood enzymes in the urodele amphibian Pleurodeles waltl reared under standard laboratory conditions. In subsequent experiments, we will estimate and compare the physiological and biochemical conditions of P. waltl when reared under extreme temperature or microgravity conditions. The enzymes selected were glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, superoxide dismutase, catalase, isocitrate dehydrogenase and glucose-6-phosphate dehydrogenase. In fresh plasma samples, enzyme activity in females was higher than in males, except for aspartate and alanine aminotransferases, which were equivalent in females and males. Glutamate dehydrogenase activity was higher in males than in females. In female erythrocytes, the activity of all enzymes was higher than in male erythrocytes. We have also studied the storage conditions of samples and observed that for most enzymes, the activity in freshly isolated plasma and erythrocyte preparations decreased after storage at -18 or +4 degrees C.