NEGATIVE AND POSITIVE CHRONOTROPIC EFFECTS OF PROCAINE ON THE CANINE SA-NODE INSITU

  • 1 January 1979
    • journal article
    • research article
    • Vol. 241  (2) , 307-315
Abstract
In contrast to most local anesthetic agents which usually cause some degree of cardiovascular depression, procaine was an action to cause tachycardia. Effect of procaine on the SA [sinoatrial] node of the dog heart was studied in situ using a selective perfusion technique of the SA node artery. Procaine in doses from 100 .mu.g-1 mg produced a sinus depression followed by a prolonged phase of the increased heart rate. The depression became more prominent with increasing the dose. The threshold dose for inducing the tachycardiac response was lower, but the sinus acceleration was not proportional to the dose. The initial depression was not affected by atropine, but the occurrence of the stimulatory phase was inhibited by prior administration of propranolol or tetrodotoxin into the SA node artery or in the reserpine-treated dogs. The biphasic response is apparently induced by a direct negative chronotropic action of procaine on the SA node and by an indirect effect mediated by an interaction with the post-ganglionic adrenergic nerves.