title: Nitric oxide, cAMP and the biphasic muscarinic modulation of ACh release at the lizard neuromuscular junction.
abstract: In this study, we characterized the pharmacology and physiology of the automodulation of ACh release at the lizard neuromuscular junction (NMJ). The activation of muscarinic ACh receptors generated a biphasic modulation of synaptic transmission. Muscarine-induced activation of M3 receptors (0-12 min) decreased release, whereas M1 activation (> 12 min) enhanced release. Both phases of the biphasic effect are dependent on nitric oxide. However, cAMP acting via protein kinase A is also necessary for the M1 effect. In summary, we present a novel biphasic role for muscarine and implicate M3 receptors in the inhibition and M1 receptors in the enhancement of transmitter releaseat the cholinergic lizard NMJ.
authors.affiliation: Department of Biology Grinnell College 1116 8th Avenue Grinnell, IA 50112, USA.
authors.forename: Austin R
authors.initials: AR
authors.lastname: Graves
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Lewin
authors.forename: Clark
authors.initials: C
authors.lastname: A  Lindgren
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D000242:Cyclic AMP / Q000502:physiology*; D066298:In Vitro Techniques; D008116:Lizards; D009116:Muscarine / Q000494:pharmacology; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000502:physiology*; D043643:Receptor, Muscarinic M1 / Q000819:agonists / Q000502:physiology*; D043587:Receptor, Muscarinic M3 / Q000819:agonists / Q000502:physiology*
chemical_list: D043643:Receptor, Muscarinic M1; D043587:Receptor, Muscarinic M3; D009569:Nitric Oxide; D009116:Muscarine; D000242:Cyclic AMP; D000109:Acetylcholine