SEX AND AGE-DEPENDENCE OF RAT-KIDNEY SIALIDASE

Rat kidney sialidase levels have been reported to be markedly altered in pathological states such as diabetes. This was associated with a mo dification of sialic acid levels. Therefore, it was interesting to stu dy the variations of kidney sialidase and sialyltransferase activities and sialic acid content according to sex and age. This was carried ou t from birth to 210 days of age. The substrates used were sialylalpha( 2-3)[H-3]-lactitol for sialidase activity, asialofetuin and [C-14]-CMP Neu5Ac for sialyltransferase activity. In males sialidase activity inc reased until 32 days then slightly declined, In females, the activity increased and leveled off at 135 days of age. Higher sialidase activit y was observed in females than in males from 56 days of age. Gonadecto my had no effect on this activity. In both sexes, sialyltransferase ac tivity decreased markedly with age. This activity was higher in female s than in males, whereas sialic acid levels varied only moderately wit h age and were slightly higher in females.