Endothelium-derived relaxation of the pregnant and nonpregnant canine uterine artery
Matsumoto, T.; Kanamaru, K.; Sugiyama, Y.; Murata, Y.
Journal of Reproductive Medicine 37(6): 529-533
1992
ISSN/ISBN: 0024-7758 PMID: 1619606 Document Number: 394571
Vascular responses to acetylcholine (ACh) and the calcium ionophore A23187 were studied in rings of pregnant and nonpregnant canine uterine arteries. Segments were fixed vertically in Krebs-Henseleit solution, and isometric tension was measured with force-displacement transducers. In nonpregnant canine artery preparations precontracted to a stable plateau tension with norepinephrine, ACh and A23187, dose-dependent relaxation was elicited in intact rings but not in endothelium-denuded rings. This endothelium-dependent relaxation was not affected by pretreatment with indomethacin but was inhibited by pretreatment with lipoxygenase inhibitors, nordihydroguaiaretic acid and the selective 5-lipoxygenase inhibitor AA861. Therefore, relaxation appeared to be mediated by a noncycloxygenase metabolite or metabolites. Similar endothelium-dependent relaxation was also observed in pregnant canine artery preparations. The results indicate that an endothelium-derived relaxing factor might play a physiologic role in maintaining the blood flow of the uterine circulation.