TY - JOUR
T1 - Redox regulation of large conductance Ca2+-activated K+ channels in smooth muscle cells
AU - Wang, Zhao Wen
AU - Nara, Masayuki
AU - Wang, Yong Xiao
AU - Kotlikoff, Michael I.
PY - 1997/7
Y1 - 1997/7
N2 - The effects of sulfhydryl reduction/oxidation on the gating of large- conductance, Ca2+-activated K+ (maxi-K) channels were examined in excised patches from tracheal myocytes. Channel activity was modified by sulfhydryl redox agents applied to the cytosolic surface, but not the extracellular surface, of membrane patches. Sulfhydryl reducing agents dithiothreitol, β- mercaptoethanol, and GSH augmented, whereas sulfhydryl oxidizing agents diamide, thimerosal, and 2,2'-dithiodipyridine inhibited, channel activity in a concentration-dependent manner. Channel stimulation by reduction and inhibition by oxidation persisted following washout of the compounds, but the effects of reduction were reversed by subsequent oxidation, and vice versa. The thiol-specific reagents N-ehtylmalcimide and (2- aminoethyl)methanethiosulfonate inhibited channel activity and prevented the effect of subsequent sulfhydryl oxidation. Measurements of macroscopic currents in inside-out patches indicate that reduction only shifted the voltage/nP(a) following reduction did not result from recruitment of more functional channels but rather from changes of channel gating. We conclude that redox modulation of cysteine thiol groups, which probably involves thiol/disulfide exchange, alters maxi-K channel gating, and that this modulation likely affects channel activity under physiological conditions.
AB - The effects of sulfhydryl reduction/oxidation on the gating of large- conductance, Ca2+-activated K+ (maxi-K) channels were examined in excised patches from tracheal myocytes. Channel activity was modified by sulfhydryl redox agents applied to the cytosolic surface, but not the extracellular surface, of membrane patches. Sulfhydryl reducing agents dithiothreitol, β- mercaptoethanol, and GSH augmented, whereas sulfhydryl oxidizing agents diamide, thimerosal, and 2,2'-dithiodipyridine inhibited, channel activity in a concentration-dependent manner. Channel stimulation by reduction and inhibition by oxidation persisted following washout of the compounds, but the effects of reduction were reversed by subsequent oxidation, and vice versa. The thiol-specific reagents N-ehtylmalcimide and (2- aminoethyl)methanethiosulfonate inhibited channel activity and prevented the effect of subsequent sulfhydryl oxidation. Measurements of macroscopic currents in inside-out patches indicate that reduction only shifted the voltage/nP(a) following reduction did not result from recruitment of more functional channels but rather from changes of channel gating. We conclude that redox modulation of cysteine thiol groups, which probably involves thiol/disulfide exchange, alters maxi-K channel gating, and that this modulation likely affects channel activity under physiological conditions.
KW - Disulfide
KW - K(Ca) channels
KW - Sulfhydryl
KW - Thiol
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U2 - 10.1085/jgp.110.1.35
DO - 10.1085/jgp.110.1.35
M3 - Article
C2 - 9234169
AN - SCOPUS:0030808873
VL - 110
SP - 35
EP - 44
JO - Journal of General Physiology
JF - Journal of General Physiology
SN - 0022-1295
IS - 1
ER -