AMIODARONE INHIBITS INTERLEUKIN 6 PRODUCTION AND ATTENUATES MYOCARDIAL INJURY INDUCED BY VIRAL MYOCARDITIS IN MICE

A recent study has shown that amiodarone inhibits the production of cytokines in vitro. This study was performed to examine the effects of amiodarone on survival, heart weight-to-body-weight ratio (HW/BW), myocardial lesions and cytokines production in a murine model of viral myocarditis induced by the encephalomyocarditis virus (EMCV). Four-week-old male DBA/2 mice were inoculated with the EMCV. To examine its effect on survival and HW/BW on day 14, mice were administered oral amiodarone (30 mg/kg) or the vehicle only once daily, starting 4 days before inoculation of the virus. The effects of amiodarone on histopathologic changes in myocardial lesions and myocardial cytokine production were studied in mice treated with amiodarone (10 mg/kg or 30 mg/kg) or vehicle, and killed day 7. The survival rate on day 14 was significantly higher in the amiodarone-treated mice than in the control mice. The HW/BW, histopathologic score of cellular infiltration and myocardial interleukin 6 concentration were significantly lower in the amiodarone-treated group than in the control group. Likewise, myocardial necrotic area was significantly smaller in the amiodarone group than in the control group. This study suggests that the beneficial effects of amiodarone in viral myocarditis may be mediated by decreasing interleukin 6 production in myocardial tissue. [Copyright &y& Elsevier]