Dual effects of nitric oxide on the large conductance calcium-activated potassium channels of rat brain.
Previously, we have shown that nitric oxide (NO) directly activates the Maxi-K channels. In the present study, we have investigated whether NO has prolonged effects on the Maxi-K channels reconstituted in lipid bilayer. Application of S-nitroso-N-acetyl-D, L-penicillamine (SNAP), a NO donor, induced an immediate increase of open probability (Po) of Maxi-K channel in a dose-dependent manner. When SNAP was removed from the cytosolic solution, the Po did not simply returned to, but irreversibly decreased to a level lower than that of the control Po. At 0.2 mM, (Z)-[N-(3-Ammoniopropyl)-N-(n-propyl)amino] diazen-1-ium-1,2-diolate (PAPA-NO), another NO donor, produced a similar increase of Po and decrease of Po upon washout. The increasing effects of SNAP on Po were not blocked by either 50 U/ml superoxide dismutase (SOD) or 2 mM Nethylmaleimide (NEM) pre-treatments. However, NEM appears to be ineffective when applied after SNAP. These results suggest that NO can modulate Maxi-K channel via direct interaction and chemical modification, such as Snitrosylation in the brain.
Lee
Ji Eun
JE
Department of Physiology and Biophysics, Inha University College of Medicine, 253 Yonghyun-dong, Nam-gu, Incheon 402-751, Korea.
Kwak
Jiyeon
J
Suh
Chang Kook
CK
Shin
Jung Hoon
JH
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000378:metabolism; D005033:Ethylmaleimide / Q000378:metabolism; D006834:Hydrazines / Q000378:metabolism; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000502:physiology; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism*; D008051:Lipid Bilayers; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000378:metabolism; D051381:Rats; D026423:S-Nitroso-N-Acetylpenicillamine / Q000378:metabolism
D004791:Enzyme Inhibitors; D006834:Hydrazines; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008051:Lipid Bilayers; D020030:Nitric Oxide Donors; C112653:PAPA NONOate; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D005033:Ethylmaleimide