Acetylcholine (Abrrev., ACh.)-An acetic acid ester of choline. It is a cholinergic agonist, acting as a neurotransmitter at myoneural junctions of striated muscle, autonomic effector cells innervated by parasympathetic nerves, parasympathetic nerves, and at preganglionic synapses of both sympathetic and parasympathetic nervous systems. Basically, this means ACh (and related compounds) stimulates muscles and glands innervated (supplied with nerves) from the parasympathetic nervous system.
ACh produced by the human body is rapidly hydrolised by acetylcholinesterase (AChE), therefore, synthetically identical preparations of ACh are not very useful. However, synthetic derivatives (similar structure, but not identical), exert their effects for a longer duration and are therefore, more pharmacologically suitable. ACh is used as a vasodilator (widenes vessel diameter) in pharmacoangiography [angiographical (radiographic study of blood vessels), technique where blood flow is manipulated (increasing, decreasing) using drugs].
ACh and related drugs lethal in small doses. For example, the fatal dose of ACh by injection is only 20mg. Emergency measures for acute or chronic poisoning include maintaining artificial respiration until an antidote can be given. Antidote- Atropine, 2mg slowly intravenously.