PPADS, a novel functionally selective antagonist of P2 purinoceptor-mediated responses.

We have characterized PPADS (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid) as a novel antagonist which selectively blocks P2 purinoceptor-mediated responses in rabbit vas deferens at pre- and postjunctional sites. PPADS did not interact with alpha 1-adrenoceptors, muscarinic M2 and M3 receptors, histamine H1 and adenosine A1 receptors. Thus, PPADS is a novel and useful pharmacological tool to study co-transmission in tissues where ATP and co-existing neurotransmitters act in concert.