Effect of somatostatin on myoelectrical activity of small bowel

Somatostatin, a growth hormone-release inhibiting hormone, has been found to be a powerful inhibitor of gastric and pancreatic secretion as well as of hormone release in the digestive system. This study was undertaken to determine the influence of somatostatin on the myoelectrical activity pattern of the small bowel. Three conscious dogs were prepared with electrodes spaced 25 cm apart along the entire small intestine. Intravenous infusions of somatostatin were administered in various doses (0.6--5.0 microgram/kg.h) while spike activity and slow waves were recorded under fasting conditions, after a meat meal, or during intravenous infusion of gastrin, caerulein, or insulin. Somatostatin at a dose of 0.6 microgram/kg.h almost doubled the frequency of the interdigestive myoelectric complex. Somatostatin in fed dogs caused a dose-dependent decrease of the normal fed spike activity, and at higher doses it induced a pattern like that seen in fasting animals. The slow-wave frequency in both fasted and fed conditions was not changed significantly. We conclude that somatostatin given under basal conditions increases the frequency of the interdigestive complex and, when administered after feeding, converts the fed-type pattern to the fasted-type pattern. It may therefore play a promoting role in initiating the interdigestive myoelectric complex.