Effect of dinitrophenol on potential, resistance, and H+ rate of frog stomach

Abstract

Gastric mucosae were mounted between chambers, some with Cl– bathing solutions and some with Cl–-free bathing solutions. The effect of 2,4-dinitrophenol (DNP) was determined on the potential difference (PD), resistance, and H+ secretory rate. In Cl– experiments, the H+ rate was depressed to low levels without a marked decrease in the PD, and the PD did not vary linearly with the H+ rate. Neither ATP (6 mm) nor voltage clamping (nutrient + 150 mv) restored H+ secretion. The PD is inverted in Cl–-free solutions (nutrient is negative), and under these conditions DNP produced a decrease in the H+ rate which varied linearly with the decrease in the absolute magnitude of the PD. An analysis of this latter finding, on the basis of the separate-site theory of gastric HCl formation, revealed that during inhibition of H+ secretion only the electrogenic H+ mechanism is affected; the parameters of the return circuit within the mucosa are not changed. Under Cl–-free conditions the resistance and emf of the H+ mechanism were estimated; the resistance ranged from 571 to 1,350 ohm/cm2, and the emf from 33 to 56 mv.