Effects of verapamil on cardiac arrhythmias and expression of Cx43 protein in isolated rat hearts subjected to perfusion with high concentration of calcium.

<p>(A) Protocols for <i>ex vivo</i> arrhythmia study. (B) Total arrhythmia scores during 45 min of perfusion period. Anti-arrhythmic property of verapamil at 0.3 µmol/L was evaluated. (C) Immunoblots of Cx43 expression. Representative immunoblots of samples from rat ventricles subjected to 45 min of perfusion with high concentration of calcium in the absence and presence of verapamil. (D) Quantitative densitometric analysis of Cx43 protein with tubulin as an internal standard. All values are expressed as mean ± SD. <i>n</i> = 12 for arrhythmia analysis. <i>n</i> = 8 for Western blot analysis. Control: normal calcium (1.5 mmol/L) perfusion group; high calcium: high calcium (3.3 mmol/L) perfusion group; high calcium+verapamil: high calcium (3.3 mmol/L) perfusion in the presence of verapamil (0.3 µmol/L) group. **<i>P</i><0.01<i> </i>vs. control, ^##<i>P</i><0.01 vs. high calcium group.