The influence of sympathetic nervous activity on the antiarrhythmic efficacy of diphenylhydantoin

Abstract

The efficacy of diphenylhydantoin as an antagonist for ouabain induced ventricular rhythm disorders was determined in spinal cats exhibiting signs of low and high adrenergic neural activity. In cats with high heart rates and blood pressures, diphenylhydantoin was effective in increasing the lethal dose of ouabain. On the other hand, in animals with slow heart rates and low blood pressures, diphenylhydantoin produced no increase in the lethal dose of ouabain. After diphenylhydantoin administration both groups of ouabain intoxicated animals behaved similarly with respect to heart rates, blood pressures, rate of ventricular tachycardia and lethal dose. These data indicate that diphenylhydantoin produces a reduction in adrenergic activity and that this reduction may account for the drug's antiarrhythmic activity.