Predominant role for nitric oxide in the relaxation induced by acetylcholine in human uterine artery

Abstract

The effect of acetylcholine on the isolated human uterine artery rings was investigated. Acetylcholine (10-10 M to 6× 10-5 M) induced concentration- and endothelium-dependent relaxation (pD2=7.4±0.02, maximal response was 77.5±6.3% of relaxation induced by papaverine at 3×10-4 M), diethylcarbamazine (10∼4 M) and tetra-ethylammonium (3×10-4 M) had no effects on acetylcholine-evoked relaxation. Methylene blue (10-5 M) and NG-monomethyl-L-arginine (L-NMMA) (3×10-6 to 3× 10-5 M) antagonized relaxation induced by acetylcholine. The inhibition of endothelium-dependent relaxation by L-NMMA (10-5 M) was reversed by L-arginine (10-5 M) but not by D-arginine (10-4 M). It is concluded that in uterine artery acetylcholine induces endothelium-dependent relaxation. It is suggested that the acetylcholine-induced relaxation of isolated uterine artery is probably mediated via endothelial nitric oxide formation © 1994 Oxford University Press.