Asymmetrical distribution of ion channels in canine and human left-ventricular wall

Epicardium versus midmyocardium

Gergely Szabó, N. Szentandrássy, T. Bíró, Balázs I. Tóth, G. Czifra, J. Magyar, Tamás Bányász, A. Varró, László Kovács, P. Nánási

Research output: Contribution to journalArticle

94 Citations (Scopus)

Abstract

The aim of the present study was to compare the distribution of ion currents and the major underlying ion channel proteins in canine and human subepicardial (EPI) and midmyocardial (MID) left-ventricular muscle. Ion currents and action potentials were recorded from canine cardiomyocytes derived from the very superficial EPI and central MID regions of the left ventricle. Amplitude, duration and the maximum velocity of depolarization of the action potential were significantly greater in MID than EPI myocytes, whereas phase-1 repolarization was more pronounced in the EPI cells. Amplitudes of the transient outwards K+ current (29.5±1.5 vs. 19.0±2.3 pA/pF at +50 mV) and the slow component of the delayed rectifier K+ current (10.3±2.3 vs. 6.5±1.0 pA/pF at +50 mV) were significantly larger in EPI than in MID myocytes under whole-cell voltage-clamp conditions. The densities of the inwards rectifier K+ current, rapid delayed rectifier K+ current and L-type Ca2+ current were similar in both cell types. Expression of channel proteins in both canine and human ventricular myocardium was determined by Western blotting. In the canine heart, the expression of Kv4.3, Kv1.4, KChIP2 and KvLQT1 was significantly higher, and that of Nav1.5 and MinK much lower, in EPI than in MID. No significant EPI-MID differences were observed in the expression of the other channel proteins studied (Kir2.1, α1C, HERG and MiRP1). Similar results were obtained in human hearts, although the HERG was more abundant in the EPI than in the MID layer. In the canine heart, the EPI-MID differences in ion current densities were proportional to differences in channel protein expression. Except for the density of HERG, the pattern of EPI-MID distribution of ion-channel proteins was identical in canine and human ventricles.

Original languageEnglish
Pages (from-to)307-316
Number of pages10
JournalPflugers Archiv European Journal of Physiology
Volume450
Issue number5
DOIs
Publication statusPublished - Aug 2005

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Pericardium
Ion Channels
Canidae
Ions
Proteins
Muscle Cells
Action Potentials
Epirubicin
Depolarization
Clamping devices
Mink
Muscle
Cardiac Myocytes
Current density
Heart Ventricles
Myocardium
Western Blotting
Electric potential
Muscles

Keywords

  • Action potential
  • Canine myocytes
  • Epicardium
  • Human heart
  • Ion channels
  • Ion currents
  • Midmyocardium
  • Regional differences

ASJC Scopus subject areas

  • Physiology

Cite this

Asymmetrical distribution of ion channels in canine and human left-ventricular wall : Epicardium versus midmyocardium. / Szabó, Gergely; Szentandrássy, N.; Bíró, T.; Tóth, Balázs I.; Czifra, G.; Magyar, J.; Bányász, Tamás; Varró, A.; Kovács, László; Nánási, P.

In: Pflugers Archiv European Journal of Physiology, Vol. 450, No. 5, 08.2005, p. 307-316.

Research output: Contribution to journalArticle

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