Experimental Studies Of Taurine Magnesium Coordination Compound On The Ion Channel Currents In Guinea Pig Ventricular Cardiomyocytes

Objective: To investigate the antiarrhythmic mechanism of taurine magnesiumcoordination compound (TMC) on sodium current (I_Na, L-type calcium current (I_{Ca, L}), delayed rectifier potassium current (I_K), inward rectifier potassium current (I_K1) insingle ventricular cardiomyocytes of guinea pig.Methods: Single ventricular cardiomyocytes of guinea pig were obtained byLangendorff regressive perfusion. Only the cells with rod shaped and clear crossstriations were used for experiments. The whole-cell patch clamp recording techniquewas used to observe the changes of sodium current (I_Na), L-type calcium current (I_{Ca, L}), delayed rectifier potassium current (I_K), inward rectifier potassium current (I_K1) underthe different concentration of TMC.Results:1. TMC at 100, 200μmol·L^-1 decreased peak I_Na from -28.00±2.11 and -28.01±2.30pA/pF to -25.67±2.11 and -24.92±2.48pA/pF and inhibition ratio were 8.33±0.92, 11.15±2.13％(n=5, p＜0.01), respectively. The I_Na I-V curve was shiftedupwards without changes of their active, peak and reverse potentials.2. TMC at 50, 100, 200μmol·L^-1 increased peak I_{Ca, L} from -4.99±1.28, -6.01±1.15 and -4.21±0.90pA/pF to -5.62±1.41, -7.59±1.36 and -5.79±1.22pA/pF, andincrement ratio were 12.85±3.10, 26.64±4.50 and 37.55±2.40％(n=5, p＜0.01), respectively. The I_{Ca, L} I-V curve was shifted downwards without changes of theiractive, peak and reverse potentials. TMC turned the I_{Ca, L} steady-state inactivationcurve to right.3. At+70mV, TMC at 50, 100, 200μmol·L^-1 decreased I_K amplitude from 8.35±1.14, 8.65±1.38 and 8.67±1.04pA/pF to 7.13±1.30, 6.94±1.45 and 6.31±1.16pA/pF, and inhibition ratio were 15.04±3.91, 20.23±3.87 and 27.73±5.1％(n=5, p＜0.01), respectively. The I_K I-V curve was shifted downwards.4. TMC did not inhibit I_K1 with no change on reversal potential (n=5, p＞0.05)Conclusion: TMC blocks I_Na; TMC increase I_{Ca, L} in a concentration dependentmanner and probably acts on its inactive state; TMC blocks I_K in a concentration dependent manner; these could be the important mechanisms of its antiarrhythmic andits cardioprotective effects.