Effect of calcium on intracellular pH

The effect of intracellular calcium on intracellular pH in the turtle urinary bladder was examined with phosphorus nuclear magnetic resonance. The turtle urinary bladder is capable of acidification in vitro and urinary acidification by this membrane is inhibited by an increase in intracellular calcium. Since calcium is capable of altering intracellular pH, it remains unclear whether the inhibition of urinary acidification is the result of an increase in intracellular pH. In the present study, intracellular calcium was increased by the cholinergic agent, carbachol, the ionophore A23187 and replacement of extracellular Na by sucrose. All agents decreased intracellular pH in the turtle bladder, thus suggesting that inhibition of urinary acidification by these agents is not due to an increase in intracellular pH.