Epinephrine stimulates human muscle lipoprotein lipase activity in vivo

Lipoprotein lipase (LPL) is involved in lipoprotein metabolism and nutrient partitioning in both adipose tissue and skeletal muscle, and LPL activity is regulated by various hormones and the nutritional state. However, the ac tion of catecholamines has not been thoroughly investigated in humans. Ther efore, the effects of exogenous epinephrine on skeletal muscle LPL (SM-LPL) activity and whole-body lipid oxidation were studied. Muscle biopsies were obtained from eight healthy subjects before, during, and after epinephrine infusion. Somatostatin was infused to suppress endogenous insulin producti on and insulin was infused at a constant rate to maintain basal insulin lev els throughout the study. After an equilibrium period (120 minutes), epinep hrine (0.05 mu g/kg/min) was infused for another 120 minutes. Epinephrine s timulated SM-LPL activity by 21.8% +/- 6.8% above basal levels from 1.44 +/ - 0.25 to 1.69 +/- 0.28 mu mol free fatty acid (FFA)/h/g muscle (P < .02), increased plasma FFA 270% from 0.147 to 0.544 mmol/L (P < .05), and increas ed lipid oxidation 45% from 4.37 to 6.36 mg/kg/min (P < .05). The increase in SM-LPL activity was positively correlated with the increase in whole-bod y lipid oxidation (R = .75, P < .05). Finally, lipid oxidation and SM-LPL a ctivity were negatively correlated with whore-body glucose oxidation, Overa ll, the results demonstrate that epinephrine is able to stimulate SM-LPL ac tivity in humans, and thus may have opposite effects on adipose tissue and SM-LPL activity. Copyright (C) 1999 by W.B. Saunders Company.