Effect of magnesium sulfate on calcium channels in isolated cardiomyocytes of guinea pig

AIM: To determine the effect of MgSO4 on calcium channel in heart cells and its anti-arrhythmic mechanism. METHODS: Whole cell recording patch-clamp technique. RESULTS: The calcium current (Ica) in the ventricular cells of guinea pig was enhanced from 1.6+/-0.6 nA to 1.9+/-0.4 nA (P<0.05) by magnesium 0.3 mmol/L in the extracellular solution, and recovered to 1.7+/-0.5 nA after washout (P<0.05 vs extracellular magnesium 0.3 mmol/L, P>0.05 vs normal Tyrode). Ica was decreased with increasing concentrations of MgSO4 (from 0.3 to 6 mmol/L) in the outside-cell solution. MaSO4 4 mmol/L attenuated Ica from 1.5+/-0.6 nA to 0.9+/-0.5 nA (P<0.05) and gained it to 1.3+/-0.4 nA after washout (P<0.01 vs MgSO4 4 mmol/L, P<0.05 vs normal Tyrode). Furthermore, the current-voltage curves (I-V curves) of Ica were elevated without its voltage dependency being affected. CONCLUSION: MaSO4 concentration-dependently regulated L-type calcium channels in ventricular myocytes.