Activation of Lipoprotein Lipase

Abstract

Injection of heparin into a number of animal species releases lipoprotein lipase into the circulation. We have studied the effect of heparin added in vitro to the lipase activity in post-heparin serum from six mammalian species. With the exception of man, all animals were studied under anesthesia. Our results demonstrate that only post-heparin serum from the rat developed increasing lipoprotein lipase activity when increasing concentrations of heparin were added to the assay system. Heparin decreased activity in the other species. These results prompted us to test the effect of adding rat serum to post-heparin serum from the other species in the presence of increasing concentrations of heparin. Rat serum stimulated lipoprotein lipase activity markedly. In guinea pigs, post-heparin serum activity increased 2,700% at a heparin concentration of 1.0 U/ml in the assay system. This effect may be related to the extremely low level of high-density lipoprotein in the guinea pig and the presence of a unique high-density lipoprotein in the rat.