title: Sulfur dioxide derivatives modulate Na/Ca exchange currents and cytosolic [Ca2+]i in rat myocytes.
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.
authors.affiliation: Shanghai Clinical Center for Endocrine and Metabolic Disease, Shanghai Institute of Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Disease, Ruijin Hospital, China. afnie@126.com
authors.forename: Aifang
authors.initials: A
authors.lastname: Nie
authors.forename: Ziqiang
authors.initials: Z
authors.lastname: Meng
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D032342:Muscle Cells / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D019831:Sodium-Calcium Exchanger / Q000737:chemistry*; D013458:Sulfur Dioxide / Q000737:chemistry*
chemical_list: D019831:Sodium-Calcium Exchanger; D013458:Sulfur Dioxide; D010042:Ouabain; D009543:Nifedipine; D002118:Calcium