[Ionic mechanisms of endothelium-dependent relaxation of vascular smooth muscle under the action of acetylcholine].

Acetylcholine and nitroglycerin were shown to induce relaxation in muscles of the ring vascular segments of canine coronary arteries and rabbit aortic archs, the magnitude of the reaction depending on the level of initial tonic tension. Methylene blue abolished the relaxation. Mechanical removal of endothelium abolished the reaction to acetylcholine but not to nitroglycerin. Verapamil decreased the relaxation by 70%. The endothelium-dependent relaxation seems to be connected mainly with a decrease in the calcium entering vascular smooth muscle cells through voltage-dependent channels.