title: Different responses to acetylcholine in the presence of nitric oxide inhibitor in rat aortae and mesenteric arteries.
abstract: 1. This study compared the relaxation induced by acetylcholine (ACh) in aortic and mesenteric arterial rings from Sprague-Dawley (SD) rats in the presence and absence of inhibitors of the known endothelium-derived relaxing factors. 2. ACh-induced relaxations were completely blocked by methylene blue and N omega-nitro-L-arginine (LNNA) in aortae, whereas these were only partially attenuated by methylene blue and LNNA in mesenteric arteries. 3. This methylene blue-resistant relaxation of ACh was partly attenuated by potassium channel blockers (tetraethylammonium and barium) but not affected by LNNA, indomethacin and calcium-free solution. 4. These results suggest that there may be another endothelial relaxing factor which is not nitric oxide (NO), prostanoids or endothelium-derived hyperpolarizing factor (EDHF) in mesenteric arteries but not in aortae. This unknown factor seems to be extracellular calcium ([Ca2+]0)-independent.
authors.affiliation: Department of Pharmacology, National Defense Medical Center, Taipei, Taiwan, Republic of China.
authors.forename: C C
authors.initials: CC
authors.lastname: Wu
authors.forename: S J
authors.initials: SJ
authors.lastname: Chen
authors.forename: M H
authors.initials: MH
authors.lastname: Yen
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D001011:Aorta / Q000187:drug effects*; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D008638:Mesenteric Arteries / Q000187:drug effects*; D008751:Methylene Blue / Q000494:pharmacology; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009569:Nitric Oxide / Q000037:antagonists & inhibitors*; D019335:Nitroarginine; D051381:Rats; D017207:Rats, Sprague-Dawley; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
chemical_list: D013757:Tetraethylammonium Compounds; D019335:Nitroarginine; D001464:Barium; D009569:Nitric Oxide; D019789:Tetraethylammonium; D001120:Arginine; D000109:Acetylcholine; D002118:Calcium; D008751:Methylene Blue; D007213:Indomethacin