Effects of cyanide and dinitrophenol on membrane properties of single nerve fibers

Abstract

Exposure of frog single nerve fibers to cyanide or to dinitrophenol results in a decline in spike height without change in either the resting membrane potential or in the maximal limiting response obtained during strong hyperpolarization. Effects of cyanide are completely reversible; those of dinitrophenol, only partially so. These data are taken to indicate that cyanide depresses the steady state level of the sodium conductance h factor before it produces any appreciable change in either the sodium or potassium equilibrium potentials as a result of interference with the metabolically linked sodium-potassium exchange mechanism. Strong hyperpolarization is effective in overcoming this ‘sodium inactivation’ in the depressed fiber so that the membrane potential approaches a normal sodium equilibrium potential at peak of activity.