Agonists and Antagonists for Purinergic Receptors.

Membrane receptors that are activated by the purine nucleoside adenosine (adenosine receptors) or by purine or pyrimidine nucleotides (P2Y and P2X receptors) transduce extracellular signals to the cytosol. They play important roles in physiology and disease. The G protein-coupled adenosine receptors comprise four subtypes: A, A, A, and A. The G-protein-coupled P2Y receptors are subdivided into eight subtypes: P2Y, P2Y, P2Y, P2Y, P2Y, P2Y, P2Y, and P2Y, while the P2X receptors represent ATP-gated homomeric or heteromeric ion channels consisting of three subunits; the most important subunits are P2X1, P2X2, P2X3, P2X4, and P2X7. This chapter provides guidance for selecting suitable tool compounds for studying these large and important purine receptor families.