Acetylcholine

What it isThe neurotransmitter at muscarinic and nicotinic receptors throughout the autonomic and somatic systems.

Why it mattersAlmost every cholinergic drug is described by whether it mimics, blocks or preserves it.

What it changesIts rapid hydrolysis by acetylcholinesterase is why cholinesterase inhibitors, not receptor agonists, are the practical way to raise cholinergic tone.