Effects of procaine amide on the electrophysiologic properties of the canine ventricular conducting system

M. R. Rosen, C. Merker, H. Gelband, B. F. Hoffman

Research output: Contribution to journalArticle

71 Scopus citations

Abstract

Microelectrode techniques were used to study effects of procainamide (PA), 10 to 90 μg/ml, on electrophysiological properties of canine Purkinje fibers (PF) and ventricular muscle perfused with Tyrode's solution containing 2.5, 4.0 or 5.5 mM KCl. Automaticity of spontaneously beating PF decreased within 40 min of perfusion with [PA] = 10 μg/ml; this was the only consistent electrophysiological change at [PA] < 30 μg/ml. After 30 min of perfusion with [PA] = 30 μg/ml, action potential amplitude and maximal slope of phase 0 decreased, and conduction throughout the ventricular conducting system was slowed, especially that in ventricular muscle. The voltage time course of repolarization was altered in such a way that action potentials dissimilar in duration, recorded from sites proximal to, distal to and at the area of maximum action potential duration became similar. Simultaneously action potential duration measured to full repolarization and effective refractory periods were prolonged. Changes were most prominent at [K+]0 = 2.5 and least apparent at [K+]0 = 5.5 mM. At [PA] = 90 μg/ml the aforementioned changes were accentuated.

Original languageEnglish (US)
Pages (from-to)438-446
Number of pages9
JournalJournal of Pharmacology and Experimental Therapeutics
Volume185
Issue number3
StatePublished - Dec 1 1973

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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