Electrophysiological Consequences of Acute Regional Ischemia/Reperfusion in Neonatal Rat Ventricular Myocyte Monolayers
- 2 December 2008
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Circulation
- Vol. 118 (23), 2330-2337
- https://doi.org/10.1161/circulationaha.108.789149
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 (Ca i ) 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.Keywords
This publication has 39 references indexed in Scilit:
- Spatially discordant alternans in cardiomyocyte monolayersAmerican Journal of Physiology-Heart and Circulatory Physiology, 2008
- Coverslip hypoxia: a novel method for studying cardiac myocyte hypoxia and ischemia in vitroAmerican Journal of Physiology-Heart and Circulatory Physiology, 2004
- Wavebreak Formation During Ventricular Fibrillation in the Isolated, Regionally Ischemic Pig HeartCirculation Research, 2003
- Two Types of Ventricular Fibrillation in Isolated Rabbit HeartsCirculation, 2002
- Initiation and propagation of ectopic waves: insights from an in vitro model of ischemia-reperfusion injury.American Journal of Physiology-Heart and Circulatory Physiology, 2002
- Purkinje involvement in arrhythmias after coronary artery reperfusionAmerican Journal of Physiology-Heart and Circulatory Physiology, 2002
- Frequency Analysis of Ventricular Fibrillation in Swine VentriclesCirculation Research, 2002
- Dynamics of Intramural and Transmural Reentry During Ventricular Fibrillation in Isolated Swine VentriclesCirculation Research, 2001
- Distribution of Excitation Frequencies on the Epicardial and Endocardial Surfaces of Fibrillating Ventricular Wall of the Sheep HeartCirculation Research, 2000
- The effect of acute coronary artery occlusion on subepicardial transmembrane potentials in the intact porcine heart.Circulation, 1977