Lipoprotein lipase in cultured pig aortic smooth muscle cells

Acetone powder extracts prepared from cultured pig aortic smooth muscle cells and the culture medium from these cells (particularly when incubated with heparin) were shown to contain a lipolytic enzyme which was identified as lipoprotein lipase by the following criteria: 1) stimulation by apolipoprotein C-II; 2) an optimal activity at approximately pH 8.0; 3) inhibition by NaCl, and 4) binding to a heparin-Sepharose affinity column. In addition, we found that cultured arterial smooth muscle cells from guinea pig and rabbit secreted a similar lipase into the culture medium. In contrast, studies using cultured bovine aortic endothelial cells yielded no evidence for either the synthesis or secretion of lipoprotein lipase by these cells. The production of lipoprotein lipase by the smooth muscle cells of the artery may play a role in the process of atherogenesis.