Two Types of Relaxation-Mediating P2 Receptors in Rat Gastric Circular Muscle

[摘要] References(27)Cited-By(2)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 μM), inhibited the relaxant responses to ATP, adenosine 5′-O-(2-thiodiphosphate) (ADPβS) and α, β-methylene ATP but not that to adenosine, while a P1-receptor antagonist, 8-phenyltheophylline (3 μM) did vice versa. The inhibitory effect of suramin was more potent for the relaxant responses to α, β-methylene ATP than those to ATP or ADPβS. Pyridoxal-phosphate-6-azophenyl-2′, 4′-disulphonic acid (PPADS) (3 - 30 μM) and 4, 4′-diisothiocyanatostilbene-2, 2′disulphonate (DIDS) (30 and 100 μM) inhibited the relaxation caused by α, β-methylene ATP but not by ATP, ADPβS or adenosine. These results suggest that ATP and ADPβS cause relaxation via the classical P2Y receptors resistant to PPADS and DIDS. In addition, α, β-methylene ATP causes relaxation via the distinct P2 receptors sensitive to PPADS and DIDS in rat gastric circular muscle.

[学科分类] 药理学

[关键词] ATP;Purinoceptor;Suramin;PPADS;DIDS