Vasoactive intestinal polypeptide and somatostatin in experimental endogenous gram-negative peritonitis

Vasoactive intestinal polypeptide (VIP) and somatostatin were measured during endogenous gram-negative peritonitis and septicaemia in rats. Both peptides were found to increase in blood, but not in peritoneal fluid. The VIP values coincided with the levels of endotoxin and bacterial counts. However, if the development of profound shock was prevented by intravenous fluid supply, scarcely any changes in plasma VIP or somatostatin were found. Somatostatin is known to inhibit VIP. Our findings suggested breakdown of this regulatory inhibition in lethal gram-negative sepsis. They also supported the concept that specific release of the peptides takes place, not merely passive diffusion from injured cells.