Nonendothelial-derived nitric oxide activates the ATP-sensitive K+ channel of vascular smooth muscle cells.
To determine whether endogenous nitric oxide (NO) opens the ATP-sensitive K+ channel (KATP channel), we investigated the effect of nonendothelial-derived NO on this channel in cultured smooth muscle cells of the porcine coronary artery by the patch-clamp technique. In the cells pretreated with endotoxin, the addition of 10(-4) M L-arginine generated NO and activated the KATP channel. Activation of this channel was suppressed by pretreatment with 10(-3) M NG-methyl-L-arginine or 10(-3) M Nx-nitro-L-arginine methyl ester, each of which is a specific antagonist of the L-arginine-NO pathway, and by 10(-6) M Methylene blue, which blocks guanylate cyclase. The activation of the KATP channel by L-arginine-NO pathway is expected to produce hyperpolarization of the cell membrane and relaxation of vascular smooth muscle cells.
Miyoshi
H
H
Second Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.
Nakaya
Y
Y
Moritoki
H
H
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects; D004731:Endotoxins / Q000494:pharmacology; D005905:Glyburide / Q000494:pharmacology; D008839:Microelectrodes; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009569:Nitric Oxide / Q000494:pharmacology*; D015221:Potassium Channels / Q000145:classification / Q000187:drug effects*; D013552:Swine; D019323:omega-N-Methylarginine
D004731:Endotoxins; D015221:Potassium Channels; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D001120:Arginine; D005905:Glyburide