To study the cytobiological basis of constriction dysfunction and arrhythmia in cardiac muscle cells with viral myocarditis.The expression of connexin 43 and desmin in cardiac muscle cells of mice with experimental viral myocarditis was determined by immunohistochemistry.In normal mice, connexin 43 and desmin are located in the intercalated disks of cardiac muscle, and the latter also revealed a positive immunoreactivity in the cross striations of sarcomeres. In viral myocarditis, the expression of both became much weakened, can even become negative.In myocarditis, expression of connexin 43 and desmin in the involved cardiac muscle cells was inhibited, resulting in dysfunction of gap junctional communication and arrhythmia.