[Effect of dexamethasone on Coxsackie B-2 virus-infected rat beating heart cells in culture].

The effects of dexamethasone (Dex) on cultured rat beating heart cells infected with 100 TCID-50 Coxsackie virus B-2 (CB2V) were observed. The beating % began to decrease in the infected group 2 or 3 d post-challenge. Meanwhile, the cytopathic effect (CPE) appeared rapidly from 1+ to 3+. In the infected and Dex-treated group 1 h after inoculation, the beating % and CPE in the whole flask were significantly higher and less, respectively, than that in the group infected (P less than 0.05) at the same intervals. At 5 d after challenge, the beating % in the whole flask was significantly higher than that in the infected group. The cardiac enzyme-aspartate aminotransferase (AST) in the infected group was higher than that in the infected and Dex-treated group (P less than 0.01) through 3-5 d post-challenge. Moreover, the AST levels in these 2 groups were also higher than that in the uninfected group, Dex control group at the same intervals (P less than 0.01). Ultrastructural findings were parallel to the results of CPE through 1-5 d post-challenge in these 4 groups. It is suggested that the protective effect of Dex on cultured beating heart cells infected with CB2V occurred in the early stages after infection. It is surmised that steroids can probably save the lives of patients with severe myocarditis if the conventional therapy for protecting the myocardium and improving immunity were administered together.