EFFECT OF MAGNESIUM-SULFATE OU CALCIUM CHANNELS IN ISOLATED CARDIOMYOCYTES OF GUINEA-PIG

AIM. To determine the effect of MgSO4 an calcium nel in heart cells an d its anti-arrhythmic mechanism. METHODS: Whole cell recording patch-c lamp technique. RESULTS: The calcium current (I-Ca) in the ventricular cells of guinea pig was enhanced from 1.6 +/- 0.6 nA to 1.9 +/- 0.4 n A (P < 0.05) by magnesium 0.3 mmol . L(-1) in the extracellular soluti on, and recovered to 1.7 +/- 0.5 nA after washout (P < 0.05 vs extrace llular magnesium 0.3 mmol . L(-1), P > 0.05 vs normal Tyrode). I-Ca wa s decreased with increasing concentrations of MgSO4 (from 0.3 to 6 mmo l . L(-1)) in the outside-cell solution. MgSO4 4 mmol . L(-1) attenuat ed I-Ca 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(-1) P < 0.05 vs normal Tyrode). Furthermore, the current-voltage curves (I-V curves) of I-Ca was elevated without its voltage dependency being affe cted. CONCLUSION: MgSO4 concentration-dependently regulated L-type cal cium channels in Ventricular myocytes.