Postheparin plasma lipolytic activities in physically active and sedentary men after varying and repeated doses of intravenous heparin.

We sought to determine the optimal dose of heparin for evaluating the activities of lipoprotein lipase (LPLA) and hepatic triglyceride hydrolase (HTGLA) in postheparin plasma. Nine physically active and ten sedentary men (age 30 +/- 5 yr, mean +/- SD) received 30, 50, 75, and 100 IU/kg of heparin in random order during a 2-week period. Based on all the samples, the average LPLA in the athletes was 43% higher (P less than 0.001) and HTGLA was 19% lower than in the untrained subjects (NS). The greatest LPLA was obtained after a heparin dose of 75 IU/kg, but LPLA after the three highest doses were not significantly different. There was also a dose effect on HTGLA (P less than 0.001) with greatest activities following doses of 75 and 100 IU/kg. Despite these dose effects, subjects maintained their rank order for both postheparin lipase activities regardless of the heparin dose. The only exception was for LPLA in the sedentary men probably because of lower LPLA and a smaller range of values. We also examined the effect of repeated daily injections of 75 IU/kg heparin on LPLA, HTGLA, and serum lipids. Repeated heparin administration on three consecutive days produced no significant effects on the apparent lipase activities. When all subjects were combined, HDL-cholesterol was increased over time (P less than 0.05) due to increases in both the HDL2 (P less than 0.05) and HDL3-cholesterol (NS) subfractions. Infusion of heparin or saline on three consecutive days into 18 additional men, however, had no effect on any lipid parameter.(ABSTRACT TRUNCATED AT 250 WORDS)