Effect of heparin on insulin secretion in vivo and in vitro.
The effect of heparin of therapeutic dose on the basal insulin secretion and on that of induced by glucose stimulation was studied in dogs and in Langerhans islets in vitro model. The effect of heparin, given intraarterially (a. pancreaticoduodenalis sup.) and injected i.v. before i.v. glucose load, on the immuno-reactive insulin concentration of the pancreatic and peripheral venous blood as well as the blood sugar and free fatty acid levels of the peripheral venous blood was investigated. Heparin inhibited significantly both the basal insulin secretion and that of following glucose stimulation. After the injection of heparin the glucose assimilation coefficient decreased significantly. The inhibitory effect of heparin on the basal insulin secretion and the glucose stimulated insulin secretion was observed in Langerhans islets in vitro model, too. This suggests that heparin, at least partly, inhibits insulin secretion directly through its influence on the beta cells.