Oxidative stress has been implicated in the pathogenesis of acute
myocarditis. The imbalance between the occurrence of
reactive oxygen species and the cellular
antioxidant defense mechanism plays a key role in myocardial injury of viral
myocarditis.
Carvedilol, a nonselective
beta-adrenoceptor antagonist with additional alpha1-adrenergic blocking and
antioxidant properties, has been shown to be cardioprotective in experimental
myocarditis. However, the expression of
4-hydroxy-2-nonenal (4-HNE), the most reliable marker of lipid peroxidation, has not been studied, and the antioxidative effects of
carvedilol have not been investigated in the setting of acute viral
myocarditis. This study was therefore designed to determine whether levels of
lipid peroxides are elevated in the myocardium and whether
carvedilol reduces the lipid peroxidation level and increases
antioxidant enzyme activities. In a coxsackievirus B3 murine
myocarditis model (Balb/c), effects of
carvedilol and
metoprolol on 14-day survival rate, myocardial histopathological changes, cardiac function, the expression of 4-HNE, virus titers,
malondialdehyde (MDA),
superoxide dismutase (SOD) and
glutathione peroxidases (GSH-Px) activities were studied. Lipid peroxidations including 4-HNE and MDA, were elevated in murine coxsackievirus-induced acute viral
myocarditis.
Carvedilol, but not
metoprolol, improved survival, reduced lipid peroxidations including 4-HNE and MDA, and increased
antioxidant enzyme activities including SOD and GSH-Px with amelioration of acute viral
myocarditis. These results show that
carvedilol but not
metoprolol exerts some of its beneficial effects by inhibiting peroxidants.