Inhibitory effect of sorbin on pepsin secretion in conscious cats and rabbits

Sorbin, a 153 amino acid polypeptide isolated from porcine upper small inte stine and its shortest synthetic derivative, the C-terminal heptapeptide (C 7-sorbin), substituted by D alaninamide in the last position (D7-sorbin), h ave proabsorptive and antisecretory effect in the different parts of the in testine. We showed that labeled C7-sorbin accumulated not only in the enter ocytes and the enteric nervous system but also in the gastric chief cells i n the rat. The chief cell secretion of pepsin was then studied in two other species, the cat and the rabbit, simultaneously with the acid secretion of parietal cells. Lipase secretion was studied in the rabbit because lipase is exclusively secreted by the upper cells of the fundic glands, which do n ot secrete pepsin. The animals were equipped with a gastric fistula, fully innervated, and a Heidenhain pouch, vagally denervated, during a continuous perfusion of pentagastrin (PG) 2 mu g/kg . h and vasoactive intestinal pep tide (VIP) 4 mu g/kg . h. D7-sorbin (100 pmol/kg . h) inhibited cat and rab bit pepsin secretion from the innervated gastric fistula secretion and from the cat denervated Heidenhain pouc secretion, but was without effect on ac id secretion and lipase secretion. These data indicate that the inhibitory effect of sorbin is specific on chief cells because the acid parietal cell secretion in both species and lipase upper cell secretion of the Fundic gla nds, in the rabbit, are not implicated. (C) 2000 Elsevier Science Inc. All rights reserved.