Ventricular arrhythmias are a common clinical manifestation in patients with acute myocardial infarction submitted to coronary revascularizaton. Reperfusion arrhythmias have been associated with successful myocardial reperfusion during thrombolytic therapy, but they have been also suggested to be a marker of large infarct size and worse prognosis. Ischemic postconditioning (PostC) has been shown to reduce the incidence of reperfusion arrhythmias. However, the mechanisms involved in the

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... thmic effects of ischemic PostC are not well known. The aims of this study were (1) to analyze the electrophysiologycal effects of ischemic PostC on passive myocardial electrical properties, as a surrogate of gap junctional communication, in isolated rat hearts, and (2) to assess the involvement of connexin 43 (Cx43) in these effects, using isolated hearts from wild-type mice and from mice devoid of connexin 43. Methods and results: Isolated rat hearts were submitted to 20 min of global ischemia followed by 25 min of reperfusion. Myocardial electrical impedance (tissue resistivity and phase angle) was assessed