The novel pyridoxal-5′-phosphate derivative PPNDS potently antagonizes activation of P2X 1 receptors

Abstract

Pyridoxal-5′-phosphate-6-(2′-naphthylazo-6′-nitro-4′,8′-disulfonate) (PPNDS) potently antagonized P2X 1 receptor-mediated responses in rat vas deferens (p K B=7.43) and Xenopus laevis oocytes (pIC 50=7.84). It showed lower (up to 20,000-fold) inhibitory potency on ecto-nucleotidase in Xenopus oocytes and on P2Y 1 receptors in guinea-pig ileum (p A 2=6.13). PPNDS did not interact with α 1A-adrenoceptors, adenosine A 1 and A 2B, histamine H 1 and muscarinic M 3 receptors. Thus, PPNDS is a novel, specific P2 receptor antagonist and represents the pyridoxal-5′-phosphate derivative with the highest potency at P2X 1 receptors.