Abstract: Objective To study the expression of connex in 43 g apjunction prote in of cardiomyocytes in ventricular hypertrophy rats induced by isoprote renol(ISO).Methods Myocardial hypertrophy model of rat was induced by injection of ISO 4 mg(1kg·d),two times a day for 5 days.Body,heart,and left ventricular mass of the rats were weighted.Transdiameter of cardiomyocyte(TDM)and cardiomyocyte area(CA)were measured under microscope.Pathological changes in cardiomyocytes with HE staining were observed.The expression of connex in 43 in cardiomyocytes wasmeasured using mimunocy tochemistry and western bloting.Results Compared with the control group,the ratio of heart mass/body mas,sleft ventricular mass/body mass,TDM,and CA increased markedly(P<0.05,P<0.01).The direction of myocardial fiber was diso rdered in ISO group.The cell size was unequal and cell density became lower than that of the control group.Immunola beling of connexin 43 was confined to the intercalated disks in the normal ventricular myocytes of control rats.But hypertro phied cardiomyocytes of ISO rats showed dispersion of connex in 43 mimunolabelled over the cell surface and in the cytoplasm.The result of western bloting showed decreased expression of connexin 43 in ISO group.Conclusion Myocardial hypertrophy induced by ISO is associated with the expression of connex in 43 and ISO accelerates gapjunction degradation.