Preliminary Studies on the Physiological Effect of a Porcine Ileal Polypeptide on Stomach Contractility in Canine Antrum and Rat Fundus
Koziol, Wladyslaw W.
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A porcine ileal polypeptide, PIP, has been isolated from porcine ileal mucosa by precipitation with (NH4)2S04, followed by fractionation by gel filtration. The protein has a molecular weight of 13,000 daltons as determined by SDS electrophoresis, and was found to contain 124 residues as determined by amino acid composition. PIP has been shown to inhibit gluconeogenesis in isolated rat hepatocytes. In isolated parietal cells of the canine stomach, PIP has been found to stimulate acid secretion at hormonal levels. More recently, Wider has studied the effect PIP has on acid secretion in the rat stomach in vivo. Preliminary results suggest that PIP stimulates acid secretion. This paper describes the results of a preliminary study on the effect of PIP on stomach smooth muscle contractility in canine antrum and rat fundus in vitro. Muscle strips were studies in vitro using established organ bath techniques. Although definitive conclusions can not be reached, the results suggest that PIP may stimulate relaxation in the rat fundus longitudinal muscle and slightly stimulate contractility in the canine antrum circular muscle. The results from this line of inquiry merit further investigation on PIP's role in the gastrointestinal tract.