acetylcholine (ACh) /as′ətilkō″lēn, əsē′til-/ , a direct-acting cholinergic neurotransmitter agent widely distributed in body tissues, with a primary function of mediating the synaptic activity of the nervous system and skeletal muscles. Its half-life and duration of activity are short because it is rapidly destroyed by acetylcholinesterase. Its activity also can be blocked by atropine at the junctions of nerve fibers with glands and smooth muscle tissue. It is a stimulant of the vagus and autonomic nervous system and functions as a vasodilator and cardiac depressant. It also has an effect at the neuromuscular junction that causes muscle contraction. Acetylcholine is used therapeutically as an adjunct to eye surgery and has limited benefits in certain circulatory disorders because of its short half-life.
