The role of β-
adrenergic stimulation on viral
myocarditis has been investigated in animal models. The beneficial action of the β-blocker
carvedilol in murine viral
myocarditis can be explained partly by the resulting heart rate reduction and the inhibition of proinflammatory
cytokine production. The modulation of myocardial
necrosis and contractile dysfunction by proinflammatory
cytokines may be partially mediated by the production of
nitric oxide (NO). The selective I(f) current inhibitor
ivabradine reduces the heart rate without affecting cardiac contractility and has been shown to be cardioprotective in failing hearts. However, little is known about the effects of
ivabradine in viral
myocarditis, and in particular, its effects on inducible
NO synthase (iNOS) have not been investigated. This study was therefore designed to examine the effects of
ivabradine in murine viral
myocarditis. In a coxsackievirus B3 murine
myocarditis model, the effects of
ivabradine and
carvedilol on the myocardial histopathological changes and
fibrosis, NO production, iNOS
protein and
cytokine levels were studied. Both
ivabradine and
carvedilol similarlyattenuated myocardial lesions and
fibrosis, inhibited NO synthesis by iNOS, and decreased the production of TNF-α and
IL-6. These results show that
ivabradine has a therapeutic benefit in murine CVB3-induced
myocarditis. The beneficial effects of
ivabradine in viral
myocarditis are partially mediated by the inhibition of both the production of proinflammatory
cytokines and the synthesis of NO by iNOS.