Muscarinic acetylcholine receptor M3 (CHRM3) (CHRM3)

The Muscarinic acetylcholine receptor M3 (CHRM3) is a G protein-coupled receptor (GPCR) that is widely expressed in smooth muscles, exocrine glands, and the central nervous system (UniProt P20366). It primarily couples to the Gq/11 signaling pathway, which activates phospholipase C and increases intracellular calcium levels, leading to physiological responses such as bronchoconstriction, gastric acid secretion, and glandular salivation (StatPearls, "Physiology, Muscarinic Receptor"). In clinical practice, the M3 receptor is a major therapeutic target for respiratory conditions like chronic obstructive pulmonary disease (COPD) and asthma, where its overactivity contributes to airway narrowing (PubMed, PMC2695207). Glycopyrrolate is a potent, quaternary ammonium muscarinic antagonist that binds to the M3 receptor to block the action of acetylcholine, thereby inducing bronchodilation and reducing excessive secretions (PubChem CID 3494). Because M3 receptors are also found in the bladder and salivary glands, drugs targeting this receptor often carry risks of systemic anticholinergic side effects such as xerostomia, blurred vision, and urinary retention (NIH, LiverTox).

Other names

M3 muscarinic receptorCholinergic receptor muscarinic 3M3RHM3

Competitive antagonism of acetylcholine at the M3 muscarinic receptor, inhibiting Gq-protein mediated activation of phospholipase C and reducing intracellular calcium mobilization.