BIPHASIC RESPONSE OF SA NODE OF DOG HEART INVIVO TO SELECTIVE ADMINISTRATION OF KETAMINE

  • 1 January 1977
    • journal article
    • research article
    • Vol. 228  (1) , 108-117
Abstract
In contrast to other i.v. anesthetic agents, ketamine has unique effects on the cardiovascular system and causes a prolonged increase in arterial blood pressure and heart rate following an initial transient depression. Effect of ketamine on the SA [sinoatrial] node of the dog heart was studied in vivo using a selective perfusion technique of the SA node artery. Ketamine injections in doses from 100 .mu.g-3 mg into the artery produced a depression of SA nodal activity by a direct action. This depression was followed by the sudden appearance of a stimulatory phase. Bilateral vagotomy and sympathectomy or prior administration of a ganglion blocker failed to inhibit occurrence of the ketamine-induced tachycardia, while it was completely abolished in reserpinized dogs or by prior injection of a .beta.-blocking agent into the SA node artery. An activation of the peripheral adrenergic mechanism may play an important role in the induction of the excitatory effect of ketamine injected into the SA node artery.

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