Intracellular pH, H ion flux and H ion permeability coefficient in bullfrog toe muscle.

1. The dimethyloxazolidinedione (DMO) technique was used to estimate intracellular pH (pH(i)) in bullfrog toe muscles incubated in vitro. The control value of pH(i) was 7.16 + +/- 0.01 (S.D.).2. pH(i) was affected by changes in P(CO2) and external bicarbonate ion concentration ([HCO(3) (-)](0)). At a given P(CO2), decreasing the external [HCO(3) (-)] was more effective in lowering pH(i) than increasing the external [HCO(3) (-)] was in increasing pH(i).3. On the assumption that the changes in pH(i) were due to hydrogen ion [H(+)) movements across the membrane, a H(+) flux of 10(-13) mole/cm(2). sec was calculated. The corresponding H(+) permeability coefficient was 10(-3) cm/sec.4. The variability of the tissue CO(2) buffer value was examined.