Stabilization of liver lipase in vitro by heparin or by binding to non-parenchymal liver cells

Abstract

The effect of heparin on the secretion of acylglycerol hydrolase activity by isolated parenchymal liver cells was studied. In the presence of heparin, the lipase activity, secreted in 3 h, was almost doubled. Heparin did not influence the activity of the enzyme, but affected the stability of the enzyme. In the absence of heparin, the triacylglycerol hydrolase activity declined to 50% of the initial value during 1 h incubation at 37°C. The addition of heparin prevented this loss of activity almost completely. The optimal stabilization of enzyme activity was reached at 15 U heparin/ml NaCl (1 M) and protamine sulphate (120 μg/ml) abolished this effect of heparin. Instead of heparin, liver lipase activity could also be stabilized by binding to non-parenchymal liver cells. The results are discussed in connection with the binding of the enzyme in vivo.