P2 purinoceptors account for the non-nitrergic NANC relaxation in the rat ileum

Rita Benkó, Sarolta Undi, Matyas Wolf, Klara Magyar, Zsuzsanna Tóvölgyi, Zoltan Rumbus, Lorand Barthó

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Abstract

The transmitters involved in the non-nitrergic component of the non-adrenergic, non-cholinergic (NANC) inhibitory response of the rat small intestinal longitudinal muscle to electrical field stimulation of its nerves is a matter of controversy. The present study is the first one to utilise a combination of a nitric oxide synthase inhibitor and a P2 purinoceptor antagonist for studying this response. We found that the P 2 purinoceptor antagonist pyridoxalphosphate-6-azophenyl-2′, 4′-disulphonic acid (PPADS; 5×10-5 M) abolished the non-nitrergic NANC relaxation to electrical field stimulation (10 Hz). PPADS alone provided a significant, moderate inhibitory action. PPADS specifically inhibited relaxations due to exogenous adenosine 5′-triphosphate (ATP) or α,β-methylene ATP. The guanylate cyclase blocker 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10-6 M) did not add to the inhibitory action of NG-nitro-L-arginine on field stimulation-induced relaxation. ODQ abolished the relaxant effect of the nitric oxide donors nitroglycerin or sodium nitroprusside. These data indicate that: (1) nitric oxide and ATP fully account for the field stimulation-induced relaxation in the rat ileal strip under the experimental conditions of this study, and (2) no ODQ-sensitive guanylate cyclase-mediated mechanism is involved in the non-nitrergic component of the NANC relaxation.

Original languageEnglish
Pages (from-to)319-324
Number of pages6
JournalNaunyn-Schmiedeberg's Archives of Pharmacology
Volume373
Issue number4
DOIs
Publication statusPublished - Jul 1 2006

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Keywords

  • NANC relaxation
  • Nitric oxide
  • P purinoceptors
  • Purinergic nerves
  • Small intestine (rat)

ASJC Scopus subject areas

  • Pharmacology

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