CNS and PNS

ACh receptors

Nicotinic (N) ACh receptor - ligand-gated Na+/K+ channels

2 subtypes: NN and NM

Muscarinic ACh receptor - G-protein-coupled receptors via 2nd messengers

5 subtypes M1-5

remember M1 (brain), M2 (heart) and M3 (GI, GU, airway, eyes)

Muscarininc agonists

Binding of cholinomimetic agents to the muscarinic receptors on Endothelial wall stimulates the relese of nitric oxide (NO), aka endothelium-derived relaxing factor  (EDRF).

NO -+> guanylate cyclase -+> increases cGMP -+> activates Ca pump which causes Ca EFflux from the cells

End result is vascular wall smooth muscle relaxation