Substrate dependency for HCl secretion by isolated piglet gastric mucosa

Abstract

Gastric mucosa was isolated from newborn piglets and bathed with balanced salt solutions. In the presence of glucose (ca. 0.01 M), this gastric preparation has been shown to be responsive to histamine by relatively prompt and vigorous H+ secretory rates. Secretion is dependent on glucose concentration in the serosal bathing solution, showing saturation kinetics with an apparent Km of about 2 mM glucose. Acetate and pyruvate were about as effective as glucose in sustaining H+ secretory rates. Short-chain fatty acids supported secretory rates that were significantly lower than rates measured with glucose. The order of effectiveness was butyrate greater than valerate greater than hexanoate greater than propionate. The results show absolute dependence of H+ secretion by piglet gastric mucosa on exogenous substrate and the preferential utilization of carbohydrate sources as substrates for secretion. They suggest that it is unlikely for any specialized and essential involvement of fatty acids in the primary H+ secretory mechanism as had been previously proposed.