Intracellular pH of the urinary bladder and red blood cells of the fresh water turtle.

Intracellular pH is thought to play an important role in several aspects of cell function including urinary acidification. The turtle urinary bladder is capable of urinary acidification in vitro and it is considered an analogue of the mammalian distal nephron. In the present study we measured intracellular pH in the epithelial layer of the turtle urinary bladder utilizing phosphorus nuclear magnetic resonance. In 14 experiments, the intracellular pH of the stripped turtle bladder epithelium bubbled with compressed air was 6.91 +/- 0.02; in turtle red blood cells the mean intracellular pH was 6.97 +/- 0.05 (n = 20), a value not significantly different from the pH value obtained in the turtle bladder. Gassing the turtle bladder with 95% air and 5% CO2 while maintaining the extracellular pH constant resulted in a rapid decrease in intracellular pH. Lowering of extracellular pH with HCl also resulted in a decrease in intracellular pH. The results demonstrate that phosphorus nuclear magnetic resonance allows rapid, noninvasive measurement and frequent monitoring of intracellular pH in the turtle bladder.