Purinergic signalling in the lower urinary tract.

The aim of this review is to describe the conceptual steps contributing to our current knowledge of purinergic signalling and to consider its involvement in the physiology and pathophysiology of the lower urinary tract. The voiding reflex involves ATP released as a cotransmitter with acetylcholine from parasympathetic nerves supplying the bladder and ATP released from urothelial cells during bladder distension to initiate the voiding reflex via P2X3 receptors on suburothelial low threshold sensory nerve fibres. This mechanosensory transduction pathway also participates, via high threshold sensory nerve fibres, in the initiation of pain in bladder and ureter. Treatment of prostate and bladder cancer with ATP is effective against the primary tumours in animal models and human cell lines, via P2X5 and P2X7 receptors, and also improves the systemic symptoms associated with advanced malignancy. Acupuncture is widely used for the treatment of urinary disorders, and a purinergic hypothesis is discussed for the underlying mechanism.