RESUMO
Previous studies have shown that free radical reactions may play an important role in the pathogenesis of the adverse effects of the antiarrhythmic agent amiodarone. The aim of this study was to investigate the role of free radical reactions in amiodarone-induced changes in the cell-mediated immune response. Therefore, we investigated the effects of amiodarone alone and in combination with either vitamin E or silymarin on (a) spontaneous blast transformation of splenocytes, (b) concanavalin A (con A)-induced proliferation of splenocytes at three different lectin concentrations, and (c) the content of conjugated dienes in liver homogenate. Forty-eight male Fischer 344 rats were randomized to one of the following groups: 1, control; 2, amiodarone; 3, vitamin E; 4, amiodarone+vitamin E; 5, silymarin; 6, amiodarone+silymarin. The con A-induced splenocyte proliferation was significantly decreased in amiodarone-treated rats at all three lectin concentrations. In the amiodarone-treated group, the change of spontaneous blast transformation was not significantly different from the control. In groups treated with amiodarone plus either antioxidant, both the spontaneous and con A-induced splenocyte proliferation were significantly increased compared with the amiodarone-treated group, and were similar to those in the control group. Amiodarone treatment significantly increased, and both silymarin and vitamin E combined with amiodarone significantly decreased, the conjugated diene content of liver homogenate compared with amiodarone treatment alone. In conclusion, free radicals generated by amiodarone may be implicated in the adverse effects of amiodarone on cell-mediated immune response, and antioxidants applied together with amiodarone may protect against or reduce both the unfavorable immunological effects of amiodarone and amiodarone toxicity.