Abstract: Objective To explore the relationship between connexin43 and ischemic arrhythmia during myocardial ischemia.Methods Barbiturate-anesthetized rats were subjected to a 30 min coronary artery occlusion. Rats were randomly assigned to control or ischemic preconditioning, and diazoxide groups. In two additional groups, rats received 5-hydroxydecanoic acid in the presence of ischemic preconditioning or diazoxide. Hemodynamics and arrhythmia were determined. Changes in phosphorylation of connexin43 were defined with quantitative immunoblotting.Results Ischemic preconditioning and diazoxide, a mitochondrial ATP sensitive potassium channel agonist induced phosphorylation of connexin43 and reduced arrhythmias as compared to control groups. The ATP sensitive potassium channel blocker 5-hydroxydecanoic acid prevented these effects in preconditioned and diazoxide hearts.Conclusion Ischemic preconditioning induces phosphorylation of connexin43 and electrical coupling by opening mitochondrial ATP sensitive potassium channel and then prevents the development of arrhythmias.

Key words: gap junction, ischemic preconditioning, cardiac muscle, arrhythmia