Modification of the action of propranolol and quinidine on 22Na- and 42K-exchange by reserpine

Abstract

The present study was undertaken to examine the influence of reserpine on the action of quinidine and propranolol to affect exchange of potassium and sodium in cat papillary muscle. The action of quinidine and propranolol to reduce K-efflux was diminished by reserpine pretreatment but the capacity of either quinidine or propranolol to increase K-influx was not altered. The action of quinidine and propranolol to reduce Na-influx was also depressed by reserpine treatment. The K-content of muscles used in the studies of K-influx was increased in reserpine-treated muscles when they were exposed to either quinidine or propranolol. The onset of the loss of responsiveness to stimulation by the muscles caused by both quinidine and propranolol was delayed but not prevented by pretreatment with reserpine. Since previous evidence suggests that the antiarrhythmic activity of quinidine and propranolol is related, at least in part, to an effect on adrenergic nervous influences in the heart, then perhaps changes in ionic fluxes induced by quinidine and propranolol are also partly related to an action on adrenergic nerve fibers. If the adrenergic nerves are previously suppressed by drugs such as reserpine, then this part of the action of quinidine and propranolol on ionic fluxes would be reduced.