In Vivo and In Vitro Electrophysiologic Effects of Terodiline on Dog Myocardium

MILTON L. PRESSLER, MARGARET R. WARNER, MICHAEL RUBART, DAVID P. RARDON, DOUGLAS P. ZIPES

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Electrophysiologic Effects of Terodiline. Introduction: Terodiline hydrochloride, widely prescribed for urinary incontinence, has been reported to cause bradycardia and torsades de pointes. Methods and Results: In this study, we characterized the electrophysiologic effects of terodiline in dog cardiac tissues in vivo and in isolated canine cardiac Purkinje fibers. Terodiline (1 to 10 μM) resulted in dose-dependent reduction of action potential amplitude and maximal upstroke velocity (V(max)). The threshold for these effects was ~2 μM (0.6 mg/L), and the changes were cycle-length dependent. Terodiline (≥ 2 μM) also depressed the action potential plateau but did not significantly alter action potential duration at concentrations ≤ 10 μM. In vivo studies demonstrated that high doses of terodiline (3 mg/kg) lengthened AH and HV intervals, slowed spontaneous sinus rate, prolonged ventricular refractoriness, and inhibited vagally induced slowing of the sinus node. Sympathetic effects on spontaneous sinus rate were unchanged. In both isolated canine Purkinje fibers and anesthetized dogs, terodiline did not evoke afterdepolarizations, repetitive firing, or ventricular tachyarrhythmias under normal or hypokalemic conditions. Conclusion: Our findings suggest that terodiline (≥ 1 to 2 μM) leads to blockade of sodium and calcium channels as well as muscarinic receptors in canine cardiac tissues.

Original languageEnglish (US)
Pages (from-to)443-454
Number of pages12
JournalJournal of cardiovascular electrophysiology
Volume6
Issue number6
DOIs
StatePublished - Jun 1995

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Keywords

  • action potentials
  • electrophysiology
  • Purkinje fibers
  • terodiline
  • torsades de pointes

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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