Effect of Ionophores on Activity of Na+,Cl–(HCO3−)-ATPase

Abstract

We studied the effects of ionophores on activity of Na⁺,Cl^–(HCO₃⁻)-ATPase. The most significant effect on the activity of this enzyme was produced by protonophore 2,4-dinitrophenol. The effect of this drug largely depended on the cation and anion composition and pH of the incubation medium and its pH. Activity of Na⁺,Cl^–(HCO₃⁻)-ATPase increased at neutral and weakly alkaline pH and decreased at pH below 6.5-6.7. In control animals (without histamine injection) with very weak or absent Na⁺,Cl^–(HCO₃⁻)-ATPase activity, the observed effect of the protonophore on ATPase activity was also virtually absent. The stimulatory effect of other ionophores (monensine, valinomycin, and A₂₃₁₈₇) was significantly weaker and depended on pH of the incubation medium, its cationic and anionic composition, and concentration of these ionophores.