Abstract
Effect of phenytoin on the membrane potential of skeletal muscle was compared between the genetically dystrophic mice and ouabain-treated mice, and the following results were obtained. 1) The resting membrane potentials of both dystrophic and ouabain-treated mice were lower than that of normal mouse (-75.1 mV). After phenytoin administration, the resting membrane potential of dystrophic mice recovered to the level of normal mice (from -69.3 to -73.6 mV) but that of ouabain-treated mice did not (from -69.6 to -70.0 mV). 2) The maximum rate of rise of action potential from both dystrophic and ouabaintreated mice was equally lower than that from normal mouse. Afte phenytoin administration, it recovered to the level of normal mouse in the dystrophic mice but not in the ouabain-treated mice. These results suggest that the stimulation of Na+ pump is not likely to be the primary cause of the recovery of membrane potential by phenytoin in the genetically dystrophic mice.
