Lipoprotein lipase activities in adipose tissues and muscle in the obese Zucker rat

Activity of lipoprotein lipase (LPL) was determined in whole adipose tissue and isolated adipocytes, and in heart and skeletal muscle that contained predominantly red or white fiber types in lean and obese Zucker rats. In rats of both sexes at 9-11 and 26-30 wk of age, no differences were observed between lean and obese rats when LPL activity of the perirenal (PR), subcutaneous (SC), and mesenteric (M) adipose tissues was expressed per millimole of tissue triglyceride. Within each sex, data relating the LPL content of isolated adipocytes to cell size was a linear function in which data for lean and obese rats fell on the same regression line. Measurement of the distribution of adipose tissue LPL activity between adipocytes and other tissue constituents showed no differences between lean and obese rats, a finding that is inconsistent with the hypothesis that obesity results in part by an alteration in adipose tissue enzyme distribution. Activity of LPL in the myocardium and red fiber types in the younger group of both sexes showed significant decreases in obese animals. This was also true for white fibers of males but not females. No differences in heart or muscle LPL between lean and obese rats were observed in the older group of either sex.