EFFECT OF REDUCING EXTRACELLULAR PH ON MEMBRANE CURRENTS OF RANVIER NODE

The effect of reducing extracellular pH (in the range from pH 7.3 to pH 4.0 at 15°C) on the membrane currents of the Ranvier node dissected from Rana esculenta has been investigated under voltage-clamp conditions. The current-voltage relationships of the sodium and potassium systems are analyzed at different pH values. The two systems are compared. The pH and voltage dependence of the relative current values of the sodium and potassium systems are described by a general equation. The equation has one set of four parameters for each of the two systems. In the sodium system the extrapolated ratios of the peak currents of the current-voltage curves (Ipeak vs. V) can be described as a dissociation curve of a weak acid with a pKa of 5.15±0.05 S.D. Furthermore, in the potassium system the current ratios at higher depolarizations can also be plotted on a dissociation curve with a pKa of 4.63±0.05 S.D. © 1969 Springer-Verlag.