Responses to bradykinin and to the bradykinin B1 receptor agonist des-Arg9-bradykinin were studied in freshly isolated rabbit carotid artery rings and in rings after a 5-h period of incubation. In freshly isolated rings precontracted with noradrenaline, neither bradykinin nor des-Arg9-bradykinin changed the tension whereas acetylcholine relaxed the vessel in a concentration-dependent manner. After incubation, des-Arg9-bradykinin, and to a lesser extent bradykinin, produced an endothelium-dependent relaxation. This response was abolished by endothelium removal, N omega-nitro-L-arginine or cycloheximide but was unaffected by indomethacin. In contrast, the response to acetylcholine was unaffected by cycloheximide and was partially inhibited by N omega-nitro-L-arginine. In addition, the relaxation curve for des-Arg9-bradykinin was markedly shifted (44-fold) by the selective bradykinin B1 receptor antagonist, des-Arg9-[Leu8]bradykinin (3 microM) and was unaffected by the bradykinin B2 receptor antagonist, Hoe 140 (1 microM). We conclude that in vitro incubation of the rabbit carotid artery induced endothelial bradykinin B1 receptors coupled to the release of endothelium-derived nitric oxide.