title: Adenosine A1 receptors are not involved in contraction of canine gastric muscularis mucosae by adenosine analogues.
abstract: In vitro contractility studies were conducted in canine gastric muscularis mucosae muscle strips with the adenosine analogues 2-chloroadenosine (CIAD), 5'-N-ethylcarboxamidoadenosine (NECA), 5'-(N-cyclopropyl)-carboxamidoadenosine (CPCA), R-N6-(2-phenylisopropyl)adenosine (R-PIA), S-PIA, N6-cyclohexyladenosine (CHA) and (2-p-carboxyethyl)phenylamino-5'-N-carboxamidoadenosine (CGS21680) as well as the A1-selective antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX). Adenosine analogues contracted the muscle strips with the following rank order of potency: CPCA > NECA > CIAD > R-PIA > CHA > S-PIA > CGS21680. CPCA, R-PIA, and CHA were partial agonists. At a concentration selective for adenosine A1 receptors (50 nM), DPCPX did not alter the concentration-response curves to CIAD or CHA. However, at higher concentrations (1-10 microM), DPCPX antagonized CIAD-mediated contractions in a competitive manner (pA2 = 6.96; slope = 0.93). CIAD-mediated contraction was not altered by treatment of the muscle strips with tetrodotoxin (1 microgram/ml) or mepyramine (1 microM). Our results indicate that adenosine A1 receptors, nerves or mast cells are not involved in contraction of canine gastric muscularis mucosae by adenosine analogues.
authors.affiliation: Intestinal Disease Research Programme, McMaster University Medical Center, Hamilton, Ont., Canada.
authors.forename: M J
authors.initials: MJ
authors.lastname: Muller
authors.forename: T
authors.initials: T
authors.lastname: Prior
authors.forename: R H
authors.initials: RH
authors.lastname: Hunt
authors.forename: P K
authors.initials: PK
authors.lastname: Rangachari
mesh_terms: D015762:2-Chloroadenosine / Q000494:pharmacology; D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019830:Adenosine-5'-(N-ethylcarboxamide); D000818:Animals; D004285:Dogs; D004347:Drug Interactions; D005260:Female; D005753:Gastric Mucosa / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure; D058915:Purinergic P1 Receptor Antagonists; D011738:Pyrilamine / Q000494:pharmacology; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000502:physiology*; D013268:Stimulation, Chemical; D013779:Tetrodotoxin / Q000494:pharmacology; D014970:Xanthines / Q000494:pharmacology
chemical_list: D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014970:Xanthines; D015762:2-Chloroadenosine; D019830:Adenosine-5'-(N-ethylcarboxamide); D013779:Tetrodotoxin; C051360:1,3-dipropyl-8-cyclopentylxanthine; D011738:Pyrilamine; D000241:Adenosine