Periprandial systemic and regional lipase activity in normal humans

An assay for plasma lipoprotein lipase activity was used without prior injection of heparin to study arteriovenous differences of lipases across skeletal muscle and adipose tissue of normal male volunteers. Lipoprotein lipase (LPL) and hepatic triglyceride lipase (HTGL) activities and triglyceride concentrations were measured in arterial plasma and in venous effluent plasma from forearm skeletal muscle and subcutaneous abdominal adipose tissue, in the postabsorptive state and after a mixed meal. Triglyceride clearance by the tissues was greater across adipose tissue than across muscle. There were no arteriovenous differences for HTGL activity. In the postabsorptive state skeletal muscle released LPL activity, but adipose tissue did not. Postprandially the arterial LPL and HTGL activities did not change. LPL activity in adipose tissue venous effluent rose, whereas that in muscle venous effluent decreased. These results show that the release of LPL from subcutaneous adipose and forearm tissues is regulated differently, reflecting in vivo differences in LPL regulation at the tissue level.