Electrophysiological effects of ouabain in 6-hydroxydopamine pretreated dogs

Canadian Journal of Physiology and Pharmacology
D GodinR A Nadeau

Abstract

Chemical sympathectomy and bilateral vagotomy were used to evaluate the contribution of each division of the autonomic nervous system in the electrophysiological actions of ouabain. Intact and chemically sympathectomized dogs were given successive and cumulative doses of ouabain until toxicity became manifest (ventricular extrasystoles and (or) ventricular tachycardia). An additional group of normal and sympathectomized animals was also submitted to bilateral vagotomy in the presence of a therapeutic dose of ouabain. Sinus cycle length, AH interval of the His bundle electrogram, atrioventricular junctional effective and functional refractory periods were increased by ouabain at therapeutic doses. These effects were no different in sympathectomized dogs than in intact dogs, indicating the absence of any significant contribution of efferent sympathetic neural activity. However, our results suggested that vagal enhancement was the main mechanism whereby ouabain produced sinus bradycardia and depression of atrioventricular conduction. Sympathectomy with 6-OHDA did not modify nor abolish ouabain toxicity. However, toxic doses were significantly higher in sympathectomized animals than in normal animals. Considering that increasing he...Continue Reading

References

Jan 1, 1988·Reviews in Clinical & Basic Pharmacology·C M LathersH Klions

Related Concepts

Autonomic Nervous System Disorders
Entire Autonomic Nervous System
Oxidopamine Hydrobromide
Ouabain
Sympathectomy, Chemical
Sinus - General Anatomical Term
Refractory Period, Electrophysiological
Hydroxydopamine
Atrioventricular Block
Oxidopamine

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