| Objective:To Study the effect of Captopril and AngiotensinⅡ(AngⅡ)on the ventricular vulnerable period,effective refractory period and intension-line in rats of normal and acute myocardial ischemia,to identify the risk factors which can induce arrhythmia,to provide the scientific evidences for preventing and curing arrhythmia and guiding clinical medication.Methods:Divide Wistar rats to AngⅡgroup:normal AngⅡgroup,normal control group,early myocardial ischemia AngⅡgroup and early myocardial ischemia control group; captopril group:normal captopril group,normal the control group,early myocardial ischemia captopril group and early myocardial ischemia control group.Determine the electrophysiology indexes including ventricular vulnerable period in stable intension,effective refractory period and the intension-intermediate stage plot by S1-S2 procedural electric stimulation.Results:①in normal rats,the VVP in the control group and AngⅡgroup were 12.00±7.63 ms;25.25±12.19 ms(P＜0.05);in rats of early myocardial ischemia,the VVP in the control group and AngⅡgroup were 20.25±6.27 ms;47.75±7.89ms(P＜0.01).AngⅡcan extend ventricular vulnerable period in rats,the effect was more effective in rats of acute myocardial ischemia.②in normal rats,the effective refractory period in the control group and AngⅡgroup were 51.00±4.66ms;40.25±8.17 ms(P＜0.05),in rats of early myocardial ischemia,the effective refractory period in the control group and AngⅡgroup were45.00±7.48ms;23.50±8.26ms(P＜0.01).AngⅡcan reduce the effective refractory period in rats,the effect was more effective in rats of early myocardial ischemia.③in rats of normal and early myocardial ischemia,AngⅡcan descend the intension-intermediate stage plot.④in normal rats,the VVP in the control group and Captopril group were 24.00±9.22 ms; 7.00±4.63 ms(P＜0.01),in rats of early myocardial ischemia,the VVP in the control group and Captopril group were 20.33±5.84ms;34.67±7.64ms(P＜0.01).Captopril can reduce ventricular vulnerable period in rats. ⑤in normal rats,the effective refractory period in the control group and Captopril group were 39.00±11.58ms;58.33±8.08 ms(P＜0.01),in rats of early myocardial ischemia,the effective refractory period in the control group and Captopril group were 34.33±8.08 ms; 44.83±6.63ms(P＜0.05)Captopril can extend the effective refractory period in rats.⑥in rats of normal and early myocardial ischemia,Captopril can upgrade the intension-intermediate stage plot.Conclusion:AngⅡcan extend window time of ventricular vulnerable period,reduce the effective refractory period and descend the intension-intermediate stage plot,then induce arrhythmia in rats of normal and early myocardial ischemia.Captopril had opposite action. Captopri can reduce window time of ventricular vulnerable period,extend the effective refractory period and upgrade the intension-intermediate stage plot.
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