P2Y2R is equally activated by ATP and UTP (EC50 = 0.3-3 μM),221 suggesting its close proximity to conditions such as inflammation and apoptosis.258 All known agonists of P2Y2R are derivatives of ATP and UDP (UDPpS, MRS2698, INS37217, INS48823, α,β-methylene-UDP, 5-bromo-UTP, PSB-1114). One such agonist INS365 (diquafosol, EC50 = 100 nM) has been approved as an ophthalmic solution for the treatment of dry eye syndrome.266 PSB1114 is another known P2Y2R agonist that possesses 60-fold selectivity over the P2Y4R or the P2Y6R.267 Two of the P2Y2R agonists INS37217 and MRS2698 are currently in clinical trials for treating cystic fibrosis.258 Thus far, there are no reports of any PET radioligand for imaging of this receptors.
