title: Two types of relaxation-mediating P2 receptors in rat gastric circular muscle.
abstract: Effects of purinoceptor antagonists on the relaxant responses to adenine nucleotides were examined to characterize the subtypes of P2-receptor in rat gastric circular muscle. In tissues contracted by acetylcholine, a P2-receptor antagonist, suramin (100 microM), inhibited the relaxant responses to ATP, adenosine 5'-O-(2-thiodiphosphate) (ADPbetaS) and alpha,beta-methylene ATP but not that to adenosine, while a P1-receptor antagonist, 8-phenyltheophylline (3 microM) did vice versa. The inhibitory effect of suramin was more potent for the relaxant responses to alpha,beta-methylene ATP than those to ATP or ADPbetaS. Pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) (3-30 microM) and 4,4'-diisothiocyanatostilbene-2,2'-disulphonate (DIDS) (30 and 100 microM) inhibited the relaxation caused by alpha,beta-methylene ATP but not by ATP, ADPbetaS or adenosine. These results suggest that ATP and ADPbetaS cause relaxation via the classical P2Y receptors resistant to PPADS and DIDS. In addition, alpha,beta-methylene ATP causes relaxation via the distinct P2 receptors sensitive to PPADS and DIDS in rat gastric circular muscle.
authors.affiliation: Laboratory of Pharmacology, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Otsuguro
authors.forename: T
authors.initials: T
authors.lastname: Ohta
authors.forename: S
authors.initials: S
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Nakazato
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001030:Apamin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005753:Gastric Mucosa / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D011732:Pyridoxal Phosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018048:Receptors, Purinergic P2 / Q000502:physiology*; D013270:Stomach / Q000187:drug effects / Q000502:physiology; D013498:Suramin / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D010975:Platelet Aggregation Inhibitors; D018048:Receptors, Purinergic P2; D013873:Thionucleotides; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D001030:Apamin; C030812:adenosine 5'-O-(2-thiodiphosphate); D011732:Pyridoxal Phosphate; D013498:Suramin; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid