Electrophysiological consequences of acute regional ischemia/reperfusion in neonatal rat ventricular myocyte monolayers

Carlos De Diego, Rakesh K. Pai, Fuhua Chen, Lai Hua Xie, Jan De Leeuw, James N. Weiss, Miguel Valderrábano

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Background - Electrophysiological changes promoting arrhythmias during acute regional ischemia/reperfusion are challenging to study in intact cardiac tissue because of complex 3-dimensional myocardial and vascular geometry. We characterized electrophysiological alterations and arrhythmias during regional ischemia/reperfusion in a simpler 2-dimensional geometry of cultured neonatal rat ventricular myocyte monolayers. Methods and Results - Optical mapping of intracellular Ca (Cai) and voltage was performed with the use of Rhod 2-AM and Rh-237, respectively. Regional ischemia was mimicked by covering the central portion of monolayer with a glass coverslip, and reperfusion was mimicked by removing the coverslip. Monolayers were stained with fluorescent antibodies to detect total and dephosphorylated connexin-43 at various time points. During coverslip ischemia, action potential duration shortened, Ca i transient duration was prolonged, and local conduction velocity (CV) slowed progressively, with loss of excitability after 10.6±3.6 minutes. CV slowing was accompanied by connexin-43 dephosphorylation. During ischemia, spontaneous reentry occurred in 5 of 11 monolayers, initiated by extrasystoles arising from the border zone or unidirectional conduction block of paced beats. On reperfusion, excitability recovered within 1.0±0.8 minutes, but CV remained depressed for 9.0±3.0 minutes, promoting reentry in the reperfused zone. As connexin-43 phosphorylation recovered in the reperfused zone, CV normalized, and arrhythmias resolved. Conclusions - Acute regional ischemia/reperfusion in neonatal rat ventricular myocyte monolayers recapitulates electrophysiological alterations and arrhythmias similar to those observed during acute coronary occlusion/reperfusion in intact hearts. During early reperfusion, slow recovery from connexin-43 dephosphorylation leads to persistent CV slowing, creating a highly arrhythmogenic substrate.

Original languageEnglish (US)
Pages (from-to)2330-2337
Number of pages8
JournalCirculation
Volume118
Issue number23
DOIs
StatePublished - Dec 2 2008

Keywords

  • Arrhythmia
  • Fibrillation
  • Ischemia
  • Optical mapping
  • Reentry
  • Reperfusion

ASJC Scopus subject areas

  • Physiology (medical)
  • Cardiology and Cardiovascular Medicine

Fingerprint

Dive into the research topics of 'Electrophysiological consequences of acute regional ischemia/reperfusion in neonatal rat ventricular myocyte monolayers'. Together they form a unique fingerprint.

Cite this