The effect of gastrointestinal hormones on the gastric microcirculation.

The purpose of the present study was to evaluate the effects of several gastrointestinal hormones on the gastric submucosal arterioles using an in vivo microscopy technique. Alteration in diameter of submucosal arterioles, 40 to 90 mu in diameter, in response to infusion of different agents into the celiac axis, was measured in the anesthetized cat. Pentagastrin, the octapeptide of cholecystokinin, natural secretin, and histamine produced arteriolar dilation. Only with histamine and the octapeptide of cholecystokinin did this occur with doses that might be considered physiological. Synthetic secretin had no vasodilator activity, suggesting the presence of a contaminating agent in natural secretin. Glucagon had no effect on the submucosal arterioles. In addition, the effect of glucagon on the smaller (10 to 30 mu) terminal and subterminal submucosal arterioles was studied in the rat by in vivo microscopy. Again no effect was observed with glucagon, but norepinephrine in small doses produced vasoconstriction.