Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Summary The effects of SCN− on H+-accumulation by inside-out gastric vesicles derived from the apical membrane of secreting oxyntic cells are reported. SCN− inhibited the formation of pH gradients in Cl− and isethionate media. In Cl−, the concentration of SCN− required to achieve a certain degree of inhibition of H+ uptake (or dissipation of preformed gradients) was increased with the increase in Cl− concentration, indicating some competitive phenomena between these anions. Comparison of the rates of dissipation of similar pH gradients achieved in Cl− vs. isethionate suggested the existence of a fast Cl−/SCN− exchange. In addition, direct isotopic fluxes confirmed the existence of rapid anion exchange and K-salt transport for both Cl− and SCN−. The rates of anion-exchange and K-salt transport were of similar magnitude, and the rates for SCN− in either countertransport against Cl− or cotransport with K+ were twice as fast as the equivalent values for Cl−. These mediated pathways in the apical membrane provide the possible means for rapid access of SCN− to the acidic canalicular spaces of the oxyntic cell that is implicit in recent proposals to explain SCN− inhibition of gastric HCl secretion.
Type of Medium: