Hydrolase Activities Increase in the Rat Aorta with Growth and Aging but Not in Liver and Kidney1

We examined specific activities (based on DNA) of six glycosidases and cathepsin C in aorta, kidney, and liver from male rats of 2, 6, 10, and 14 months of age. The premise was that assessing cellular catabolism of arterial and nonvascular tissues over age might more fully clarify the impact of age (and growth) alone upon vascular wall metabolism. All aortic glycosidases increased significantly (P <0.05) over the holding period as follows: neutral α-glucosidase, up 93%; β-galactosidase, up 102%; N-acetyl-β-glucosaminidase, up 119%; α-mannosidase, up 77%; β-glucuronidase, up 65%; acid α-glucosidase, up 95%. Cathepsin C specific activity was unchanged as was aortic DNA content; total protein content increased 136%. In the kidney, all glycosidase specific activities declined over age with decreases ranging 39–55%; cathepsin C was unchanged. In the liver, neutral α-glucosidase increased 12%, acid α-glucosidase was unchanged, and the four remaining glycosidases decreased an average of 5–35% by 14 months of age. Liver cathepsin C decreased 44% over this period. Thus, enhancement of hydrolase baseline activities prevails during growth and aging in rat aortic tissue whereas hydrolases of kidney and liver tissues generally decline.