Binge drinking is a risk factor for cardiac arrhythmias, known as the holiday heart syndrome. Atrial fibrillation (AF) is the most frequently diagnosed arrhythmia in this condition. Recent reports indicated that cardiac ryanodine receptor (RyR2) dysfunction and Ca 2+ leak contribute to alcohol-enhanced AF. In this study, we investigated whether stabilizing RyR2 with dantrolene treatment can prevent alcohol-enhanced AF in rats. A binge drinking rat model was established with alcohol (2 g /kg, IP) delivered once every other day for 4 times. The study consisted of following 3 groups: control group (n = 9), binge alcohol group (n = 10), and binge alcohol + dantrolene (A+D) group (dantrolene, 10 mg/kg, IP before each alcohol injection, n = 9). Echocardiography, left ventricular hemodynamics, in vivo atrial electrophysiology and AF inducibility test, RyR2 phosphorylation level, and blood norepinephrine level were studied 24 hours after the last injection. Ca 2+ leak in isolated atrial myocytes from control and binge alcohol rats was examined. Binge alcohol significantly increased AF inducibility (1/9 in control vs. 8/9 in binge alcohol group, P < 0.05) and AF duration. Dantrolene treatment significantly reduced both AF inducibility (2/9 in dantrolene group, P < 0.05) and AF duration. Binge alcohol significantly increased Ca 2+ leak in isolated atrial myocytes, which was reduced by dantrolene treatment. Blood norepinephrine,7 RyR2 phosphorylation level, cardiac echocardiography, and left ventricular hemodynamics were not significantly affected 24 hours after binge drinking. In conclusion, stabilizing RyR2 with dantrolene treatment significantly attenuated binge drinking-enhanced AF, suggesting that therapeutic strategies stabilizing RyR2 could be a preventive measure to blunt binge drinking-enhanced AF arrhythmogenesis.
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