Gastrointestinal secretory, motor, circulatory, and metabolic effects of prosomatostatin.

This study compares the gastrointestinal effects of somatostatin (SS) and its putative prohormone, prosomatostatin (Pro-SS), a 28-amino acid peptide isolated from the hypothalamus and the gut, in conscious dogs with chronic gastric and pancreatic fistulae. Pro-Ss suppressed the release of serum gastrin, insulin, and pancreatic polypeptide that occurs in response to feeding a meat meal in a manner similar to that seen with SS. However, in contrast to SS, which strongly reduced intestinal blood flow and oxygen consumption and stimulated intestinal motility, Pro-SS, at the doses tested, had no influence on mesenteric circulation, oxygen uptake, and intestinal motility. We conclude that Pro-SS mimics most of the gastrointestinal secretory actions of SS, but does not exhibit the intestinal circulatory, metabolic, and motor effects of SS.