Acetylcholine (ACH, ACh) 1
Acetylcholine (ACH, ACh) 1 : The neurotransmitter substance at cholinergic synapses that causes cardiac inhibition, vasodilation, gastrointestinal peristalsis, and other parasympathetic effects. It is liberated from preganglionic and post-ganglionic endings of parasympathetic fibers and from pre-ganglionic fibers of the sympathetic nervous system as a result of nerve injuries, whereupon it acts as a transmitter on the effector organ; it is hydrolyzed into choline and acetic acid by acetylcholinesterase before a second impulse may be transmitted