Table 1.
Summary of adrenergic and cholinergic receptor subtypes, effectors and ligands.
| Receptor | Subtype | Effector | Ligand |
|---|---|---|---|
| Adrenergic receptors (AR) | alpha 1 | Gq: ↑PLC, ↑PIP3, ↑DAG, ↑Ca2+ | adrenaline, noradrenaline |
| alpha 2 | Gi: ↓AC, ↓cAMP | adrenaline, noradrenaline | |
| beta 1 | Gs: ↑AC, ↑cAMP | adrenaline, noradrenaline | |
| beta 2 | Gs: ↑AC, ↑cAMP | adrenaline, noradrenaline | |
| beta 3 | Gs: ↑AC, ↑cAMP | adrenaline, noradrenaline | |
| Cholinergic receptors | Nicotinic | ↑Na+, ↑K+ | acetylcholine, nicotine |
| Muscarinic M1 | Gq: ↑ PLC, ↑PIP3, ↑DAG, ↑Ca2+ | acetylcholine, muscarine | |
| Muscarinic M2 | Gi: ↓AC, ↓cAMP | acetylcholine, muscarine | |
| Muscarinic M3 | Gq: ↑ PLC, ↑PIP3, ↑DAG, ↑Ca2+ | acetylcholine, muscarine | |
| Muscarinic M4 | Gi: ↓AC, ↓cAMP | acetylcholine, muscarine | |
| Muscarinic M5 | Gq: ↑ PLC, ↑PIP3, ↑DAG, ↑Ca2+ | acetylcholine, muscarine |
Gi = G-protein alpha subunit, group S; Gs = G-protein alpha subunit, group S; Gq = G-protein alpha subunit, group Q; PLC = phospholipase C; AC = adenylate cyclase; DAG = diacylglycerol; PIP3 = phosphatidylinositol 3,4,5 trisphosphate.