Alterations of in vitro fluid and electrolyte absorption by gastrointestinal hormones

Abstract

1. 1. A study was carried out to determine the influence of gastrin, secretin, and cholecystokinin on in vitro small intestinal absorption of fluid and electrolytes. 2. 2. Employing everted gut sacs, it was noted that these hormones inhibited the net transfer of sodium, chloride, and fluid across the small intestine of the hamster. 3. 3. Furthermore, by measuring the bidirectional fluxes of sodium (Na 22) across the small intestine, it was demonstrated that the diminution in the net transfer of this ion resulted from a decrease in the mucosal to serosal component. 4. 4. Tissue uptake of sodium (Na 22) from the serosal and mucosal side of gut segments revealed inhibition of mucosal but not serosal uptake, with maintenance of normal intracellular sodium values. 5. 5. Thus, it is thought that the primary action of these polypeptides is at the mucosal membrane of the absorbing intestinal epithelial cell. 6. 6. These results are discussed in relation to the clinical problem of the variants of the Zollinger-Ellison syndrome.