The Influence On The Excitation-Contraction Coupling Of Isolated Guinea Pig Papillary Muscle By Nicorandil

Objective: To verify the myocardial protective effects of Nicorandil by detecting its influence on isolated guinea pig papillary muscular tension and action potential during peri-ischemic period and declare its cellular mechanism.Methods: Papillary muscles isolated tenderly and quickly from 32 healthy, adult guinea pigs were divided into 4 groups randomly: blank control group (infuse with 4'C ST Thomas' II solution during ischemic period, n=8); control group (infuse with 5 u mol/L Glibenclimide 15 minutes prior to ischemia, infuse 4癈 ST Thomas' II solution during ischemic period, n=8); experimental group (infuse with 4"C ST Thomas' II solution + Immol/L Nicorandil during ischemic period, n=8); pretreatment group (infuse with 5 u mol/L Glibenclimide 15 minutes prior to ischemia, infuse with 4癈 ST Thomas' II solution+ Immol/L Nicorandil during ischemic period, n=8). Resting Potential(RP), Action Potential Ampulator(APA), Overshoot(OS), Maximum Velocity of Phase 0 Depolarization (Vmax), Time of 50% Repolarization(APD50), Time of 90% Repolarization (APD90) during peri-ischemic period, record the arrest time, defibrillation time in each group and the changes of RP in experimental group were observed and record.Results: The recovery ratio of OS and Vmax in experimental group is significantly higher than those in the other three groups (p<0.05); TheAPD50, APD90, defibrillation tune in experimental group is significantly lower than those in blank control group and pretreatment group (p<0.05); The recovery ratio of muscle tension in experimental group is significantly higher than that in the other three groups (p<0.01); The depolarized arrest time in experimental group is 141?10.93s, and the changing time to polarized or hyperpolarized arrest is 21 ?.51s.Conclusion: Nicorandil possesses the function to protect myocardium, it can ameliorate the contraction of isolated papillary muscle after ischemia and ischemia-reperfusion injury that is intimately due to its ability to open ATP sensitive potassium channel. However, this can not rule out that other mechanisms may exist co-operatively. Nicorandil can enhance the myocardial protection effects of traditional cold high-potassium crystalloid cardiopledia.