Sulfur dioxide derivatives depress L-type calcium channel in rat cardiomyocytes

1. Sulfur dioxide (SO2) has recently been found to have various biological effects on the cardiovascular system. The present study was designed to explore the effects of SO2 derivatives on the L-type calcium current (I (Ca, L)) in isolated rat ventricular cardiomyocytes. 2. A Langendorf system was used to dissociate single ventricular cells. SO2 derivatives from 5 to 1000 mu mol/L were incubated with cardiomyocytes. The whole-cell patch-clamp technique was used to record I (Ca, L). The effect of SO2 derivatives on intracellular calcium concentration ([Ca2+](i)) was detected by confocal microscopy. 3. Concentrations of 5 or 10 mu mol/L SO2 derivatives could not change I (Ca, L) evoked by a single pulse from -40 to 0 mV for 200 ms in rat ventricular cardiomyocytes; however, 50, 100, 500 or 1000 mu mol/L SO2 derivatives could depress the peak amplitudes of calcium currents in 6 min, and the I (Ca, L) was attenuated by 13.19%, 16.59%, 21.23% and 24.72%, respectively, as compared with corresponding controls (P < 0.05). The 50, 100, 500 or 1000 mu mol/L SO2 derivatives also depressed the peak I-V curves, without altering the reversal potential and the voltage dependence of the peak I (Ca, L). Therefore, 1000 lmol/L SO2 derivatives could reduce [Ca2+](i) in cardiomyocytes. 4. The results of the present study suggest that SO2 derivatives can depress I (Ca, L) in cardiomyocytes, which might have a protective effect in cardiovascular diseases.