Basic and clinical aspects of non-neuronal acetylcholine: expression of non-neuronal acetylcholine in urothelium and its clinical significance.

Recently, several reports demonstrate that non-neuronal acetylcholine (ACh) release may contribute to various pathophysiological conditions. In this review, we presented our experiments designed to evaluate the non-neuronal cholinergic system in human bladder. After insertion of the microdialysis probe, human bladder strips were suspended in an organ bath filled with Krebs-Henseleit solution, and Ringer solution was perfused into the probe. ACh release was measured by microdialysis and HPLC. The contribution of urothelium and the effects of age and stretch of bladder strips on non-neuronal ACh release were evaluated. Choline acetyltransferase (ChAT) immunohistochemical staining of bladder was also performed. Immunohistochemistry showed marked ChAT-positive staining in the urothelium. There was tetrodotoxin-insensitive non-neuronal ACh release and this was significantly higher in strips with urothelium than in strips without urothelium. The non-neuronal ACh release was increased with age. Stretch of bladder strips caused increases in non-neuronal ACh release. The stretch-induced release of non-neuronal ACh was increased with age. Our data demonstrate that there is a non-neuronal cholinergic system in human bladder and that urothelium contributes to non-neuronal ACh release. There was significant age-related and stretch-induced increase in non-neuronal ACh release. It is suggested that the non-neuronal cholinergic system may contribute to the physiology and pathophysiology of human bladder. We also discussed the clinical significance of the non-neuronal cholinergic system in human bladder.