Comparison of myocardial and adipose tissue lipase activity in the rat.

Effects of catecholamines and iodoacetamide on lipase activity (pH 6.8) and triglyceride mobilization were investigated in adipose tissue, myocardial slice and isolated perfused heart preparation of the rat. Epinephrine and isoproterenol did not enhance myocardial lipase activity in vitro and in perfused hearts. No detectable amount of fatty acid was released from myocardial slice by epinephrine in vitro. Epinephrine, however, induced an increase in lipase activity and in the amount of fatty acid released from the adipose tissue. The results suggest a difference in properties of lipase present in the myocardium and in the adipose tissue. Iodoacetamide decreased lipase activity in vitro both in the myocardium and in the adipose tissue. Triglyceride content in the perfused heart receiving iodoacetamide at 30 min of perfusion was higher than that of the control. However, there was no correlation between triglyceride mobilization and lipase activity in these 2 tissues.