title: M(2) and M(4) muscarinic receptor subtypes couple to activation of endothelial nitric oxide synthase.
abstract: In this report we studied coupling of M(2) and M(4) muscarinic acetylcholine receptors to activation of endothelial nitric oxide synthase (eNOS). Chinese hamster ovary cells that co-express the individual receptor subtypes and eNOS in a stable fashion were used as a model. Activation of eNOS was assayed by measuring increasing levels of cyclic GMP in admixed cells that contain guanylate cyclase. Activation of both M(2) or M(4) muscarinic receptors resulted in marked activation of eNOS, in a time- and concentration-dependent manner. The time course of the response exhibited a transient peak, followed by a sustained lower plateau. While the sustained phase was dependent on influx of extracellular calcium, the transient response showed dependency on both mobilization of intracellular calcium and extracellular influx.
authors.affiliation: Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Waid
authors.forename: M
authors.initials: M
authors.lastname: Chell
authors.forename: E E
authors.initials: EE
authors.lastname: El-Fakahany
mesh_terms: D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D006224:Cricetinae; D006152:Cyclic GMP / Q000096:biosynthesis; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D006801:Humans; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D043585:Receptor, Muscarinic M2; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic / Q000502:physiology*
chemical_list: D043585:Receptor, Muscarinic M2; D043588:Receptor, Muscarinic M4; D011976:Receptors, Muscarinic; D002217:Carbachol; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D006152:Cyclic GMP; D002118:Calcium