AimTo study on changes of infarcted border zone of effective refractory period ( ERP ), and expression of connexin43(Cx43) , Tyrosine hydroxylase（TH）and nerve growth factor (GAP43 ) in MI SD rat by echocardiograph,electrophysiological techniques and immunohistochemical technique.To explore relation of left ventricular remodeling, electrical remodeling and sympathetic nerve remodeling of myocardial infarction rat.Methods30 SD rats of either sex weighting 220～250 g were euthanized under chlorine hydrate 0.3 mL/100 mg anesthesia and were randomly divided into two groups: sham operation group (n=15), MI group(n=15).ResultsCompared with the sham operation group, LVIDd、LVIDs were significantly increased and EF, FS were shortened in MI group (P<0.01).Compared with the sham operation group, ERP of infarcted border zone was significantly shortened in MI group(P<0.01).Left ventricular CX43 immunofluorescence could be seen under the fluorescence microscope in two groups of rats.the fluorescence became weak in MI group.Immunohistochemistry of left ventricular 43 and TH could be seen under the light microscope in two groups of rats.Compared with the sham operation group, GAP43 and TH had significantly higher expression in MI group (P<0.01), respectively.ConclusionsVentricular remodeling, sympathetic remodeling and electrical remod-