Role of ATP-sensitive K+ -channels in hemodynamic effects of peroxynitrite in anesthetized rats.
The aim of this study was to determine whether the hypotensive and vasodilator actions of peroxynitrite in pentobarbital-anesthetized rats involve the activation of ATP-sensitive K+-channels (K+ATP-channels). The effects of the K+ATP-channel agonist, cromakalim (9-36 microg/kg, iv), peroxynitrite (0.5-10 micromol/kg iv), and L-S-nitrosocysteine (12.5-200 nmol/kg, iv) on mean arterial blood pressure (MAP) and mesenteric (MR) and hindquarter (HQR) vascular resistances were determined before and after injection of the K+ATP-channel blocker, glibenclamide (40 micromol/kg, iv). Cromakalim, peroxynitrite, and L-S-nitrosocysteine produced dose-dependent reductions in MAP, MR, and HQR. Administration of glibenclamide did not affect resting hemodynamic parameters but markedly attenuated the hemodynamic actions of cromakalim. The maximal falls in MAP and HQR produced by peroxynitrite were attenuated by glibenclamide whereas the maximal falls in MR were not affected. In addition, the duration of the hypotensive and vasodilator effects of peroxynitrite in the mesenteric and hindquarter beds were markedly diminished by glibenclamide. In contrast, glibenclamide did not affect the maximal hypotensive or vasodilator effects of L-S-nitrosocysteine or the duration of these responses. These results suggest that the hypotensive and vasodilator actions of peroxynitrite in anesthetized rats involve the activation of K+ATP-channels whereas the hemodynamic actions of L-S-nitrosocysteine do not.
Graves
Jonathan E
JE
Department of Physiology and Pharmacology, University of Georgia, Athens, GA 30602, USA.
Lewis
Stephen J
SJ
Kooy
Neil W
NW
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000758:Anesthesia; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D019806:Cromakalim / Q000494:pharmacology; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005905:Glyburide / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects*; D008297:Male; D030421:Peroxynitrous Acid / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000819:agonists / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026403:S-Nitrosothiols / Q000494:pharmacology; D014655:Vascular Resistance / Q000187:drug effects
D026902:Potassium Channel Blockers; D015221:Potassium Channels; D026403:S-Nitrosothiols; D019806:Cromakalim; D030421:Peroxynitrous Acid; D000255:Adenosine Triphosphate; C021315:S-nitrosocysteine; D003545:Cysteine; D005905:Glyburide