Key result
Acetylcholine relaxes endothelium-intact canine uterine arteries, an effect blocked by l-NOARG and indomethacin.
Why the study?
Does acetylcholine induce endothelium-dependent relaxation in canine uterine arteries, and what pathways are involved?
Does acetylcholine induce endothelium-dependent relaxation in canine uterine arteries, and what pathways are involved?
Effect estimate: pEC50 = 6.48 ± 0.01
Acetylcholine-induced relaxation of canine uterine arteries is primarily mediated by endothelial nitric oxide, with potential secondary involvement of the cyclooxygenase pathway when NO-synthase is inhibited.
Endothelial NO mediates acetylcholine relaxation in canine uterine arteries; leaves open translation to human uterine vascular function.
The effect of acetylcholine on the isolated, pre-contracted, uterine artery of non-pregnant dog was investigated. Acetylcholine-induced concentration-dependent relaxation of isolated canine uterine artery with endothelium (pEC50 = 6.48 +/-0.01, n = 37) and was without effect on arterial segments denuded of endothelium. Indomethacin, 4-aminopyridine (10-5 m) and pre-contraction with K+-rich Krebs-Ringer bicarbonate solution had no effect on acetylcholine-induced relaxation. NG-nitro-l-arginine (l-NOARG) (10-5 m) inhibited relaxation evoked by acetylcholine. Indomethacin applied with l-NOARG led to further inhibition of acetylcholine-induced relaxation. In the presence of both l-NOARG and indomethacin, 4-aminopiridine did not provoke further inhibition of acetylcholine-induced relaxation of canine uterine artery. It is concluded that the acetylcholine-induced relaxation of canine uterine artery is probably mediated by endothelial production of nitric oxide (NO). However, if NO-synthase is inhibited, acetylcholine-induced vasorelaxation may be, in part, mediated through activation of cyclooxygenase pathway.
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Pešić et al. (2003) studied this question. Acetylcholine vs. Endothelium-denuded segments and various inhibitors was evaluated on Concentration-dependent relaxation (pEC50 = 6.48 ± 0.01). Acetylcholine induced concentration-dependent relaxation of isolated canine uterine arteries with endothelium (pEC50 = 6.48), which was inhibited by l-NOARG and further by indomethacin.
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