Hypothesis / aims of study: Urothelial ATP release is thought to play an important role in bladder afferent signaling via activation of purinergic receptors on suburothelial afferent nerves. Stretch of the bladder mucosa is a well documented stimulus for ATP release in several species, including the pig . In addition, in mouse bladder, capsaicin is also an effective stimulus for ATP release, acting via stimulation of vanilloid (TRPV1) receptors . While acid is an agonist at the TRPV1 receptor, specialized acid sensing ion channels (ASICs) are also present in several organ systems . Our aim was to characterize the ATP release from pig bladder mucosa in response to stretch, acid and capsaicin.