Myocardial connexin 43 downregulation during physical exercise

TISCORNIA GISELA; MORETTA ROSALIA; ARGENZIANO MARIANA; AMORENA CARLOS; GARCIA GRAS EDUARDO

Niza

Congreso; Cardiostim; 2010

European Society of Cardiology

Myocardial Connexin 43 downregulation during physical exercise. Tiscornia, Gisela C.; Moretta, Rosalia E.; Argenziano Mariana A. Amorena Carlos E.; García Gras, Eduardo A. CESyMA, ECyT, UNSAM. Republica Argentina   In individuals suffering from certain cardiomyopathies (ARVC, HC, etc), intense physical exercise can trigger arrhythmic events. The molecular mechanism that generates such arrhythmogenic substrate is unknown. In mice models inhibition of Connexin 43 expression is arrhythmogenic. Several cardiomyopathies inhibit Connexin 43 expression per se. We hypothesized that the mechanism responsible for physical exercise induced arrhythmogenesis could be centred on an acute decrease in the expression of Connexin 43 in the ventricular myocardium. We used untrained and swim trained mice in our experiments. We evaluated the effect of swimming on the expression of Connexin 43 at the mRNA and protein levels by semi-quantitative RT-PCR and western blot respectively. In trained mice we found a 55% inhibition of Connexin 43 mRNA after exercising 15`. Connexin 43 protein suffers a 50% inhibition starting at minute 60`. The levels of inhibition are sustained in time and the recovery of Connexin 43 expression, after the exercise is finished takes up to 60`. In untrained mice we only observed mRNA expression inhibition beginning after 90` of exercise. Propranolol prevents exercise induced Connexin 43 expression inhibition indicating a central role for sympathetic stimulation. Conclusion: We report a mechanism that could explain the occurrence of arrhythmogenic events in susceptible individuals during and up to one hour after a session of physical exercise.