Redox modulation of L-type calcium channels in ferret ventricular myocytes. Dual mechanism regulation by nitric oxide and S-nitrosothiols.
The effects of NO-related activity and cellular thiol redox state on basal L-type calcium current, ICa,L, in ferret right ventricular myocytes were studied using the patch clamp technique. SIN-1, which generates both NO. and O2-, either inhibited or stimulated ICa,L. In the presence of superoxide dismutase only inhibition was seen. 8-Br-cGMP also inhibited ICa,L, suggesting that the NO inhibition is cGMP-dependent. On the other hand, S-nitrosothiols (RSNOs), which donate NO+, stimulated ICa,L. RSNO effects were not dependent upon cell permeability, modulation of SR Ca2+ release, activation of kinases, inhibition of phosphatases, or alterations in cGMP levels. Similar activation of ICa,L by thiol oxidants, and reversal by thiol reductants, identifies an allosteric thiol-containing "redox switch" on the L-type calcium channel subunit complex by which NO/O2- and NO+ transfer can exert effects opposite to those produced by NO. In sum, our results suggest that: (a) both indirect (cGMP-dependent) and direct (S-nitrosylation/oxidation) regulation of ventricular ICa,L, and (b) sarcolemma thiol redox state may be an important determinant of ICa,L activity.
Department of Pharmacology, Duke University Medical Center, Durham, North Carolina 27710, USA.
D L
DL
Campbell
J S
JS
Stamler
H C
HC
Strauss
D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D005289:Ferrets; D006352:Heart Ventricles; D008297:Male; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology; D009603:Nitroso Compounds / Q000378:metabolism; D010084:Oxidation-Reduction; D018408:Patch-Clamp Techniques; D013438:Sulfhydryl Compounds / Q000502:physiology
D015220:Calcium Channels; D009603:Nitroso Compounds; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; C002385:linsidomine; D008981:Molsidomine