Muscarinic agonists acting through M2 acetylcholine receptors stimulate the migration of an NO-sensitive guanylyl cyclase to the plasma membrane of bovine tracheal smooth muscle

摘要

Muscarinic agonists acting on bovine tracheal smooth muscle (BTSM) induce two separate cGMP signals,one at 20 sec associated with NO-sensitive-soluble-guanylyl-cyclase (NO-sGC) and another at 60 sec, linkedto natriuretic-peptide-GC. The 20-sec-cGMP novel cascade starts with mAChRs, via unknown compo-nents, activates an NO-sGC. To unravel this cascade, in crude membranes isolated from intact BTSM stripsexposed to muscarinic agonists, we detected GC activities increments at 20sec and 60sec. The 20-sec-GCis a NO-sensitive-GC, identified as α_1β_1-heterodimer. In reconstitution experiments with purified plasmamembranes and cytosol, muscarinic agonists induced an NO-sGC migration in a dose-dependent manner,being inhibited by muscarinic antagonists displaying an M_2AChR profile and blocked by PTX, suggestingthe involvement of G~o/G_i proteins. The NO-sGC related to migration was isolated and identified as an α_1β_1-heterodimer. This work shows that muscarinic agonists in BTSM induce a massive and selective α_1β_1-NO-sGC migration from cytoplasm to plasma membranes being responsible for the 20-sec-cGMP signal.