Effects of somatostatin on intestinal circulation and oxygen consumption

The effects of intraarterial administration of somatostatin upon intestinal blood flow, intestinal capillary surface area, oxygen consumption and intestinal motor activity were measured in anesthetized dogs. Blood flow to the segment of distal ileum was measured with an electromagnetic blood flow meter, and arteriovenous oxygen difference (AVO2) was determined spectrophotometrically. Intestinal oxygen consumption was calculated as the product of AVO2 and total blood flow. The clearance of 86Rb was measured to estimate the density of the perfused intestinal capillaries. Changes in blood flow distribution were estimated from the distribution of radiolabelled microspheres. Intestinal motor activity was monitored from changes in intraluminal pressure. Somatostatin induced a dose-related decrease in intestinal blood flow, capillary surface area and intestinal oxygen consumption. A significant increase in intestinal motor activity was also observed. The data of this study indicate that somatostatin acts on smooth muscle of both arterioles and precapillary sphincters and results in a potent vasoconstriction in the intestinal microcirculation.