Effects of metabolic inhibitors on the synthesis and release of lipoprotein lipase in cultured cells derived from the stromal-vascular fraction of rat adipose tissue.

Cultured cells derived from the stromal-vascular fraction of rat epididymal adipose tissue have been used to study the release of lipoprotein lipase in response to heparin. In the presence of heparin, lipoprotein lipase appeared in the medium biphasically, with an initial rapid rise followed by a slower linear release. The initial increase in activity in the medium was paralleled by a decrease in cell-associated activity. Over the course of the slower phase of release, cell-associated lipoprotein lipase levels remained constant. Treatment of cultures with cycloheximide or 2-deoxyglucose eliminated the second phase of release as well as cell-associated lipoprotein lipase activity. Treatment of cultures with Colcemid decreased the second phase of release but increased cell-associated lipoprotein lipase activity. These data suggest that exposure to heparin results in a rapid release of pre-formed enzyme and that continued release is dependent on both protein synthesis and transport of the enzyme to the cell surface.