Open AccessTwo Types of Relaxation-Mediating P2 Receptors in Rat Gastric Circular Muscle
Author(s) -
Ken-ichi Otsuguro,
Toshio Ohta,
Itó S,
Yoshikazu Nakazato
Publication year - 1998
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.78.209
Subject(s) - ppads , suramin , dids , schild regression , p2 receptor , adenosine , receptor , muscle relaxation , p2y receptor , biology , purinergic receptor , medicine , antagonist , endocrinology , chemistry , biochemistry , membrane
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.