Effect of somatostatin on glucose-induced 45Ca uptake in the pancreatic islets.

Publisher Website
Google Scholar
Abstract
Rat pancreatic islets were perifused with Krebs-Ringer bicarbonate (KRB) buffer containing 16.7 mM of glucose with somatostatin (2 .mu.g/ml) or/and diltiazem HCl [hydrochloride] (2 .times. 10-5 M). Somatostatin inhibited preferentially the early phase of glucose-induced insulin release, whereas diltiazem HCl inhibited the late one. The concomitant presence of the submaximal concentration of somatostatin (2 .mu.g/ml) and diltiazem HCl (2 .times. 10-5 M) provided the completely additive inhibition of glucose-induced insulin release. Rat pancreatic islets were incubated with KRB buffer supplemented with 16.7 mM of glucose and 45CaCl2 (10 .mu.Ci/ml) for 5-60 min and the biphasic 45Ca uptake by pancreatic islets was obtained. Somatostatin (500 ng/ml-4 .mu.g/ml) gave the suppressive effect on the early phase of glucose-induced 45Ca uptake, but the higher concentration (2 .mu.g/ml) of somatostatin did not impair the late phase of 45Ca uptake by pancreatic islets. Diltiazem HCl did suppress the late phase of glucose-induced 45Ca uptake dose-dependently, but did not suppress the early phase (2 .times. 10-5 M). Somatostatin suppresses the early phase of glucose-induced Ca2+ uptake preferentially to the late one and has a different action mechanism from Ca antagonist on glucose-induced insulin release.