Effects of dofetilide and EGIS-7229, an antiarrhythmic agent possessing class III, IV, and IB activities, on myocardial refractoriness in hyperkalemia, hypokalemia, and during β-adrenergic activation in the rabbit papillary muscle in vitro

Anikó Kovács, Gábor Szénási

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Lengthening of the effective refractory period (ERP) by EGIS-7229, a class III /Ib/ IV drug, and by dofetilide, a selective IKr blocker, was compared in normokalemia (NK), hypokalemia (LK), and hyperkalemia (HK) in right ventricular papillary muscles of rabbits paced at 0.5, 1, and 2 Hz, in vitro, and also during β-adrenergic activation. In NK, EGIS-7229 (3 and 10 μ M) and dofetilide (30 and 100 nM) similarly lengthened ERP in a steeply reverse frequency-dependent manner. The two compounds produced smaller ERP prolongations at 0.5 Hz in HK and LK, so rate-dependence of ERP changes decreased. EGIS-7229 lengthened ERP more at 2 Hz than at 0.5 Hz at 10 μM in LK, that is, the effect of EGIS-7229 turned into positive frequency-dependence from 3 to 10 μM. Furthermore, EGIS-7229 lengthened ERP at 10 μM more than dofetilide at 100 nM at 2 Hz stimulation rate (P<0.05). Isoproterenol (30 nM) eliminated the effect of dofetilide on ERP, while EGIS-7229 prolonged ERP during β-adrenergic activation. In conclusion, efficacy of EGIS-7229 was superior to that of dofetilide in LK and during β-adrenergic stimulation, suggesting improved antiarrhythmic action for EGIS-7229 under certain conditions in the patient.

Original languageEnglish
Pages (from-to)303-309
Number of pages7
JournalJournal of Pharmacological Sciences
Volume100
Issue number4
DOIs
Publication statusPublished - Apr 26 2006

Keywords

  • Antiarrhythmic agent
  • Dofetilide
  • Effective refractory period
  • Hyperkalemia
  • Hypokalemia

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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