Cathepsin Activity of Liver and Muscle Fractions of Adrenalectomized Rats

Summary Cathepsin activity was determined in muscle and liver tissue fractions of adrenalectomized rats, adrenalectomized rats supplemented with saline, pair-fed intact controls, and ad libitum-fed controls. Cathepsin activity of skeletal muscle tissue conformed to the biochemical criteria necessary to be associated with lysosomes. Adrenalectomized rats had a significant increase in free cathepsin activity in muscle and liver, and a significant increase in total activity in muscle tissue. Intact animals fed 25% of the food intake of ad libitum-fed controls had significant increases in total activity, with no significant differences in free cathepsin activity. Adrenalectomized animals maintained with saline had greater free cathepsin activity in liver and muscle than their pair-fed and ad libitum-fed controls, suggesting that the increased free activity was not due to electrolyte imbalance or starvation.