Changes in Plasma Lipids and Lipolytic Activity during Recovery from Exercise of Untrained Rats

Abstract

The activities of lipoprotein lipase in adipose tissue and heart homogenates, and epinephrine-stimulated lipase of adipose tissue were determined at the end of an exercise bout and during recovery from exercise of untrained rats. Concurrently, triglyceride and free fatty acid concentrations of plasma were measured. Lipoprotein lipase activity in adipose tissue homogenates was depressed at the end of the exercise bout and remained depressed 24 hr later. Heart lipoprotein lipase activity was significantly elevated 24 hr after the exercise bout. Basal activity of epinephrine-stimulated lipase (without epinephrine) was significantly elevated at the end of the exercise bout, remained elevated for 6 hr, but returned to control levels 12 hr later. In the presence of epinephrine, however, the activity of the enzyme was elevated at the end of the bout and throughout the 18-hr period of recovery after the exercise bout. Plasma triglyceride concentrations tended to decrease with exercise and the subsequent periods of rest with significant differences observed for the 12- and 18-hr-rested groups. Free fatty acid levels were significantly elevated immediately after exercise but returned to control levels 6 hr after the exercise bout. These findings show that certain changes in lipid metabolism resulting from a single bout of exercise, persist for some time after the termination of the exercise bout.