Abstract
Tolbutamide was administered into the superior pancreaticoduodenal artery of anesthetized dogs. A prompt hyperinsulinemia was induced but the plasma gastrin increased gradually in the right gastroepiploic vein; acutely secreted endogenous insulin did not result in gastrin secretion. These findings suggest that gastrin is not released by insulin per se, but by decreased blood glucose.
By infusion of somatostatin into the superior pancreaticoduodenal artery, plasma gastrin in the antral vein and plasma insulin in the pancreatic vein decreased promptly, and the tolbutamide-and arginine-induced gastrin and insulin secretions were impaired. These inhibitory effects of somatostatin on the plasma gastrin and insulin secretion were quite clearly demonstrated in the right gastroepiploic vein and superior pancreaticoduodenal vein. The inhibitory effect of somatostatin was more pronounced on gastrin release than on insulin release.
It appears likely that the inhibitions of gastrin and insulin secretion by somatostatin were caused by direct action on the gastrin secretory cell and on the pancreatic beta cell. Somatostatin may play an important role in the entero-insular axis.
