title: Effect of estrogen on post-heparin lipolytic activity. Selective decline in hepatic triglyceride lipase.
abstract: The rise in plasma triglyceride (TG) levels associated with estrogen administration has been thought to arise from impaired clearance because of the uniform suppression of post-heparin lipolytic activity (PHLA). Recently PHLA has been shown to consist of two activities: hepatic TG lipase and extrahepatic lipoprotein lipase (LPL). To determine whether estrogen might induce a selective decline in one of these activities, both hepatic TG lipase and extrahepatic LPL were measured in post-heparin plasma from 13 normal women before and after 2 wk of treatment with ethinyl estradiol (1 mug/kg per day). Hepatic TG lipase and extrahepatic LPL were determined by two techniques: (a) separation by heparin-Sepharose column chromatography, and (b) selective inhibition with specific antibodies to post-heparin hepatic TG lipase and milk LPL. Estrogen uniformly depressed hepatic TG lipase as measured by affinity column (-68 +/- 12%, mean +/- SD, P less than 0.001) or antibody inhibition (-63 +/- 11%, P less than 0.001). Extrahepatic LPL was not significantly changed by affinity column (-22 +/- 40%) or antibody inhibition (-3 +/- 42%). Direct measurement of adipose tissue LPL from buttock fat biopsies also showed no systematic change in the activated form of LPL measured as heparin-elutable LPL (+64 +/- 164%) or in the tissue form of LPL measured in extracts of acetone-ether powders (+21 +/- 77%). The change in hepatic TG lipase correlated with the change in PHLA (r = 0.969, P less than 0.01). However, neither the change in PHLA nor hepatic TG lipase correlated with the increase in TG during estrogen. The decrease in PHLA during estrogen thus results from a selective decline in hepatic TG lipase.
mesh_terms: D000273:Adipose Tissue / Q000201:enzymology; D000328:Adult; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008049:Lipase / Q000097:blood*; D008071:Lipoprotein Lipase / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: D014280:Triglycerides; D004997:Ethinyl Estradiol; D006493:Heparin; D008049:Lipase; D008071:Lipoprotein Lipase