Effects Of Insulin On The Action Potential From Three Membranes Of The Rabbits' Right Ventricle

Background:Phase 2 reentry [1-3] due to the increase of voltage gradient produces local currents and causes reentry,and is the course of a number of arrhythmia pathogenesis. The electrophysiological properties, action potential(AP) shape and action potential duration are significantly different among the epicardial,midcardial and endocardial cells . In pathological or drug cases, phase 2 reentry caused by the expanding of repolarization dispersion may increase the occurrence of arrhythmia. Some studies[4] prompted in insulin-dependent and non-insulin-dependent diabetic rat model,showed that action potential durations have different changes. Nishizakiz et al[5] pointed out that patients with Brugada syndrome have a high arrhythmias rate postprandial, and this may have a certain relationship with insulin. Therefore, our study used whole-cell patch clamp technique to record the APs from epicardial,midcardial and endocardial cells of Rabbits'right ventricle and observe the effects of different concentrations of insulin on APs of the three different membranes .Objective:Experiments were performed to investigate the heterogeneity of action potential and the effects of different concentrations of insulin on APs of the three different membranes of rabbit's right ventricle .Methods:The epicardial,midcardial and endocardial were obtained by Enzymes from right walls of rabbits. APs were recorded via whole-cell patch-clamp technique.Results:According to current clamp protocol, APs of the three membranes of the rabbits'right Ventricle were significantly different.①40pmol/L insulin had not significantly effect on APDs of Epi and M cells.②280,600,2400 and 4000pmol/L insulin significantly shortened APDs of Epi and M cells. ③Insulin had not significantly effect on APDs of Endo cells at the concentration of 280 and 600pmol/L.④At the concentration of 2400 and 4000pmol/L ,insulin significantly shortened APDs of Endo cells.⑤4000 pmol/L Insulin significantly decreased the APA of Epi and M cells.Conclusions:Insulin had different effects on APDs of the three membranes of rabbit's right ventricle and may increase the voltage gradient of myocyte ,which could be the mechanisms of ventricular arrhythmia.