Bradykinin-induced, N omega-nitro-L-arginine-insensitive endothelium-dependent relaxation of porcine coronary arteries is not mediated by bioassayable relaxing substances.
The effect of the arginine analogue, N omega-nitro-L-arginine (L-NNA) was studied on bradykinin-induced relaxation in porcine coronary arteries. In the presence of indomethacin (3 x 10(-6) M) and captopril (10(-6) M), treatment with L-NNA (10(-4) M) had no effect on the bradykinin-induced (10(-10)-10(-7) M) relaxations in strips contracted with U-46619. In contrast to the findings in organ chamber experiments, bradykinin-induced release of endothelium-derived relaxing factor(s) (EDRFs) was abolished after 45 min of treatment of perfused porcine coronary artery segments with L-NNA (10(-4) M) in a superfusion bioassay system. These results show that, in addition to the release of nitric oxide, endothelium-dependent relaxation of porcine coronary arteries to bradykinin involves an alternative mechanism(s), which accounts for the relaxation in the presence of L-NNA. Since the release of a relaxing mediator could not be detected from L-NNA-treated porcine coronary artery segments under bioassay conditions, it is postulated that either no diffusible factor(s) is involved in the L-NNA-insensitive endothelium-dependent relaxation, or it is mediated by an extremely labile endothelium-derived substance(s).
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001681:Biological Assay; D001920:Bradykinin / Q000494:pharmacology*; D003331:Coronary Vessels / Q000187:drug effects* / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009569:Nitric Oxide / Q000378:metabolism; D019335:Nitroarginine; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D013552:Swine; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects*
D011450:Prostaglandin Endoperoxides, Synthetic; D014662:Vasoconstrictor Agents; D019335:Nitroarginine; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001120:Arginine; D001920:Bradykinin