Nitric oxide directly activates large conductance Ca2+-activated K+ channels (rSlo).
We investigated whether nitric oxide (NO) directly activates the cloned alpha-subunit of large conductance Ca2+-activated K+ (Maxi-K) channels from rat brain (rSlo), expressed either in HEK293 cells or Xenopus oocytes. In inside-out patches, the application of S-nitroso-N-acetylpenicillamine (SNAP), a NO-releasing compound, reversibly activated the channel shifting the voltage dependent activation curve of the macroscopic Maxi-K current to the left by about 15 mV. Pretreatment of the patches with N-ethylmaleimide to alkylate free sulfhydryl groups did not prevent the effect of SNAP, suggesting that NO may directly interact with the channels. These results suggest that Maxi-K channels might be one of the physiological targets of NO in the brain.
Jeong
S Y
SY
Department of Life Science, Kwangju Institute of Science and Technology, Korea.
Ha
T S
TS
Park
C S
CS
Uhm
D Y
DY
Chung
S
S
D000818:Animals; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D021122:Protein Subunits; D051381:Rats; D026423:S-Nitroso-N-Acetylpenicillamine / Q000494:pharmacology; D014982:Xenopus laevis
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D024681:Potassium Channels, Calcium-Activated; D021122:Protein Subunits; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D005033:Ethylmaleimide