ANION REQUIREMENTS FOR GASTRIC ACID SECRETION.

The rate of hydrochloric acid production by isolated, bullfrog gastric mucosae depends critically on the supply of chloride ion to the serosal surface. Secretion of acid is negligible if chloride is completely replaced by glucuronate and gluconate ion. The experimental evidence indicates that the rate of acid secretion may be regarded as a reaction velocity, depending on chloride concentration in a manner closely resembling Michaelis-Menten kinetics. Bromide and iodide ions substitute, in varying degree, for chloride as substrate. A familiar inhibitor of gastric acid production, thiocyanate ion, appears to act by competition with chloride in a reaction leading to the formation of acid. This reaction is included in a hypothetical reaction cycle, generalized from the redox model for gastric acid production. Under certain conditions, the model predicts a dependence of secretion rate on chloride supply of the Michaelis-Menten type, as was observed.