Pancreatic spasmolytic polypeptide (PSP): III. Pharmacology of a new porcine pancreatic polypeptide with spasmolytic and gastric acid secretion inhibitory effects.

Pancreatic spasmolytic Polypeptide (PSP) is a new porcine pancreatic polypeptide, which inhibits gastrointestinal motility and gastric acid secretion in laboratory animals after parenteral as well as oral administration. (1) PSP inhibits the amplitude of electrically stimulated contractions of the isolated guinea pig ileum. PSP's inhibitory effect is antagonized by phentolamine, but not by yohimbine. (2) PSP inhibits the motility of isolated guinea pig intestinal segments after intraluminal dosing. (3) PSP reduces intestinal motility in rabbits in vivo after intravenous and intraluminal administration, and in mice in vivo after subcutaneous injection. (4) PSP delays absorption of protein hydrolysate when it is administered orally in capsules to pigs and to pancreatectomized dogs. (5) PSP inhibits pentagastrin induced gastric acid secretion in rats after oral administration and in cats after subcutaneous and oral administration. The mechanism of action of PSP has so far not been finally elucidated. It seems likely that PSP interferes with endogenous acetylcholine release. Furthermore it might act by release of somatostatin from somatostatin cells in the gastrointestinal tract. It may have a direct or an indirect stimulant effect on alpha 2-receptors.