title: Effect of extracellular calcium concentration on potency of muscarinic agonists at M1 and M2 receptors in rabbit vas deferens.
abstract: The M1 potency (decrease in neurogenic response) of carbachol, oxotremorine, muscarine, arecaidine propargly ester (APE) and 4-(4-chlorophenylcarbamoyloxy)-2-butynyltrimethylammonium iodide (4-Cl-McN-A-343) in rabbit field-stimulated vas deferens (prostatic segments) increased up to 15-fold when calcium was lowered (3.5-1.0 nM). The M2 receptor-mediated increase in twitch height in response to carbachol and the M1 affinity of pirenzepine were independent of calcium concentration (2.5 and 1.0 mM). Thus, prostatic segments of rabbit vas deferens can be used successfully at 1.0 mM calcium to determine M1 potencies of agonists and M1 affinities of antagonists without counteracting stimulation of M2 receptors.
authors.affiliation: Department of Pharmacology, University of Frankfurt, Main, F.R.G.
authors.forename: F
authors.initials: F
authors.lastname: Dörje
authors.forename: N M
authors.initials: NM
authors.lastname: Rettenmayr
authors.forename: E
authors.initials: E
authors.lastname: Mutschler
authors.forename: G
authors.initials: G
authors.lastname: Lambrecht
mesh_terms: D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004558:Electric Stimulation; D066298:In Vitro Techniques; D008297:Male; D009130:Muscle, Smooth / Q000187:drug effects*; D010277:Parasympathomimetics / Q000494:pharmacology*; D010890:Pirenzepine / Q000494:pharmacology; D011817:Rabbits; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014649:Vas Deferens / Q000187:drug effects / Q000502:physiology
chemical_list: D010277:Parasympathomimetics; D011976:Receptors, Muscarinic; D010890:Pirenzepine; D008455:(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethylammonium Chloride; D002118:Calcium