title: PPADS
text: # PPADS
  
  PPADS (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid) is a selective purinergic P2X antagonist. It is able to block contractions of rabbit vas deferens induced by ATP or α,β,methylene-ATP. It appears to be relatively selective for P2X receptors, having no appreciable activity at $α_1$ adrenergic, muscarinic $M_2$ and $M_3,$ histamine $H_1,$ and adenosine $A_1$ receptors.
  
  