Abstract
We have recently shown that sulfur dioxide (SO 2) derivatives (bisulfite and sulfite, 1:3 M/M) modulated L-type calcium, sodium, and potassium channels in rat myocytes. The aim of this study was to investigate whether SO 2 derivatives could alter Na/Ca exchanger current and the intracellular free [Ca 2+]. The nickel-sensitive Na/Ca exchanger current was measured in rat myocytes exposed to ramp pulses in Tyrode’s solution containing ouabain, nifedipine, and ±Ni (5 mmol/l). Myocytes were loaded with the fluorescent Ca 2+ indicator Fura-2/AM to estimate intracellular Ca 2+ concentration. SO 2 derivatives significantly inhibited both outward and inward Ni-sensitive Na/Ca exchanger currents without a shift in the reversal potential. The intracellular free [Ca 2+] was raised by SO 2 derivatives in several concentrations. SO 2 derivatives increased [Ca 2+] i in rat myocytes and its mechanism might involve SO 2 derivatives significantly inhibiting Na/Ca exchanger current and enhancing L-type calcium channel.
Published Version
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