POTENTIAL FUNCTIONAL ROLES OF EXTRACELLULAR ATP IN KIDNEY AND URINARY-TRACT

P2 receptors are sensitive to adenosine triphosphate (ATP) and uridine triphosphate and can be divided into two major subtypes: P2X and P2Y receptors. They are specific membrane-bound receptors which when activ ated by extracellular ATP initiate a variety of biological effects. Th e P2X receptors are ligand-gated channels, whereas the P2Y receptors a re coupled to G proteins linked to second-messenger systems. In this r eview, the potential functional roles of extracellular ATP in the kidn ey and lower urinary tract are discussed and briefly explored in the c ontext of some specific renal and urinary tract abnormalities.