title: Muscarinic suppression of the evoked N-wave by oxotremorine-M recorded in the guinea-pig olfactory cortex slice.
abstract: The effect of the muscarinic agonist oxotremorine-M has been studied on the surface-negative field potential (N-wave) evoked by orthodromic stimulation of the lateral olfactory tract in slices of guinea-pig olfactory cortex. Bath-application of oxotremorine-M (5-80 microM) or carbachol (10-300 microM) produced a reversible depression of the N-wave amplitude without affecting the lateral olfactory tract compound action potential. Oxotremorine-M was approximately 5 times more potent than carbachol in this respect, and the effects of both agonists were competitively blocked by telenzepine (5-100 nM), a selective M1-receptor antagonist. In contrast, methoctramine or AF-DX 116, two 'cardioselective' M2-receptor antagonists, had little or no blocking effect on the agonist responses. It is suggested that oxotremorine-M (like carbachol) inhibits the evoked field potential by activating presynaptic M1-type muscarinic receptors in the olfactory cortex slice.
authors.affiliation: Department of Pharmacology, School of Pharmacy, London, U.K.
authors.forename: G
authors.initials: G
authors.lastname: Bagetta
authors.forename: A
authors.initials: A
authors.lastname: Constanti
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects*; D003959:Diamines / Q000494:pharmacology; D004558:Electric Stimulation; D004569:Electroencephalography; D005071:Evoked Potentials / Q000187:drug effects; D006168:Guinea Pigs; D066298:In Vitro Techniques; D009830:Olfactory Bulb / Q000187:drug effects*; D010095:Oxotremorine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010276:Parasympatholytics / Q000494:pharmacology; D010277:Parasympathomimetics / Q000494:pharmacology*; D010890:Pirenzepine / Q000031:analogs & derivatives / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000187:drug effects*
chemical_list: D003959:Diamines; D010276:Parasympatholytics; D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; C046338:telenzepine; D010890:Pirenzepine; D010095:Oxotremorine; C042743:oxotremorine M; D002217:Carbachol; C054938:methoctramine; C048593:otenzepad