Nicotinic at all ganglia, muscarinic and adrenergic at effector organs
Expansion
Receptor map
- All autonomic ganglia (both divisions) and the adrenal medulla: nicotinic
- Parasympathetic effector organs: muscarinic (M1 to M5)
- Sympathetic effector organs: adrenergic (alpha and beta), except sweat glands which are cholinergic muscarinic
- Neuromuscular junction: nicotinic (a different subtype from ganglia)
Muscarinic effects (parasympathetic activation), summarised as DUMBBELLS: Diarrhoea, Urination, Miosis, Bronchospasm, Bradycardia, Emesis, Lacrimation, Lethargy, Salivation. This is the picture of organophosphate poisoning, treated with atropine and pralidoxime.
Antimuscarinic effects are the mirror image: dry mouth, urinary retention, blurred vision with dilated pupils, constipation, tachycardia, confusion and hyperthermia. Caused by atropine, tricyclics, antihistamines, antipsychotics and oxybutynin, and a major contributor to delirium and falls in older people through anticholinergic burden.
Beta blockade and alpha blockade produce predictable opposites: bradycardia and bronchospasm for the former, hypotension and reflex tachycardia for the latter.