Kidney in the aging cat: hexokinase, aldolase, L-alpha-glycerophosphate dehydrogenase, and lactate dehydrogenase histochemistry.

Hexokinase, aldolase, L-alpha-glycerophosphate dehydrogenase, and lactate dehydrogenase activities were determined in the kidney of the aging cat. Kidneys from 24 domestic cats 2 months to 7.5 years old in 6 age groups were examined by light microscopic and histochemical methods. Enzyme activities in anatomic components of the kidney were assessed on a quantitative basis for evaluation of mean activity between the age groups. In the cats with advancing age, renal components generally had stable activity. A significant (P less than 0.05) increase in hexokinase activity occurred with advancing age in the ascending part of the renal loop (Henle's loop) and in the distal convoluted tubule. Significant (P less than 0.05) increases in aldolase activity with aging were in cortical connective tissue, internal part of the glomerular capsule (podocytes), distal convoluted tubule, and convoluted segment (Pi) of the proximal portion of the nephron tubule. L-alpha-glycerophosphate dehydrogenase and lactate dehydrogenase activity increased significantly with aging in the convoluted (Pi) segment of the proximal portion of the nephron tubule.