Schematic representation of ATP release and its effects in the urinary bladder wall. Stretch and other sensory inputs (mediators present in the urine and mediators released from nerve processes, urothelial cells, or other compartments of the bladder wall) induce the release of ATP from urothelial cells as well as from myofibroblasts of the lamina propria and from smooth muscle cells of the detrusor. Extracellular ATP can cause increased exocytosis and endocytosis of the umbrella cells (1) via P2X and P2Y receptors; it can signal bladder filling to the CNS (2); and it can lead to detrusor contraction (3). Extracellular ATP can also be degraded into adenosine.
