Delayed rectifier potassium current in undiseased human ventricular myocytes

Norbert Iost, László Virág, Miklós Opincariu, János Szécsi, Varró András Varró, Julius Gy Papp

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76 Citations (Scopus)

Abstract

Objective: The purpose of the study was to investigate the properties of the delayed rectifier potassium current (I(K)) in myocytes isolated from undiseased human left ventricles. Methods: The whole-cell configuration of the patch-clamp technique was applied in 28 left ventricular myocytes from 13 hearts at 35°C. Results: An E-4031 sensitive tail current identified the rapid component of I(K) (I(Kr)) in the myocytes, but there was no evidence for an E-4031 insensitive slow component of I(K) (I(Ks)). When nifedipine (5 μM) was used to block the inward calcium current (I(Ca)), I(Kr) activation was fast (r=31.0±7.4 ms, at +30 mV, n=5) and deactivation kinetics were biexponential and relatively slow (τ1=600.0±53.9 ms and τ2=6792.2±875.7 ms, at -40 mV, n=7). Application of CDCl2 (250 μM) to block I(Ca) altered the voltage dependence of the I(Kr) considerably, slowing its activation (τ=657.1±109.1 ms, at +30 mV, n=5) and accelerating its deactivation (τ=104.0±18.5 ms, at -40 mV, n=8). Conclusions: In undiseased human ventricle at 35°C I(Kr) exists having fast activation and slow deactivation kinetics; however, there was no evidence found for an expressed I(Ks). I(Kr) probably plays an important role in the frequency dependent modulation of repolarization in undiseased human ventricle, and is a target for may Class III antiarrhythmic drugs.

Original languageEnglish
Pages (from-to)508-515
Number of pages8
JournalCardiovascular research
Volume40
Issue number3
DOIs
Publication statusPublished - Dec 1 1998

Keywords

  • Cell isolation
  • Human myocytes
  • K-channel
  • Ventricular arrhythmias

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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