title: Muscarine increases a voltage-independent potassium conductance through an M4 receptor in rat dorsolateral septal nucleus neurons.
abstract: The direct effect of muscarine on neurons of the rat dorsolateral septal nucleus (DLSN) was examined by using conventional microelectrode and voltage-clamp techniques. Muscarine (1-50 microM) caused a hyperpolarization accompanied by an increase of a voltage-independent potassium conductance. Pirenzepine competitively antagonized the muscarine-induced hyperpolarization with an apparent dissociation constant (Kd) value of 54 nM. Furthermore, intracellular loading with GTP gamma S, a non-hydrolyzable GTP analog, blocked irreversibly the muscarine-induced hyperpolarization. In addition, pretreatment of neurons with pertussis toxin (PTX) prevented the hyperpolarization produced by muscarine. These results suggest that muscarine hyperpolarizes DLSN neurons via a voltage-independent potassium conductance by acting at M4 subtype receptors which are coupled to a PTX-sensitive G-protein in DLSN neurons.
authors.affiliation: Department of Physiology, Kurume University School of Medicine, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Hasuo
authors.forename: T
authors.initials: T
authors.lastname: Akasu
authors.forename: J P
authors.initials: JP
authors.lastname: Gallagher
mesh_terms: D000818:Animals; D004594:Electrophysiology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009116:Muscarine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D037342:Pertussis Toxin; D010890:Pirenzepine / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011921:Rats, Inbred WKY; D011976:Receptors, Muscarinic / Q000187:drug effects / Q000378:metabolism*; D012686:Septal Nuclei / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
chemical_list: D015221:Potassium Channels; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D010890:Pirenzepine; D009116:Muscarine; D037342:Pertussis Toxin