**2.2.3.3 Muscarinic**

As stated above, muscarinic receptors play a significant role in OAB. ATP, Acetylcholine (Ach) and other "signaling molecules, interact with the afferent nerve fibers under the urothelium. Bladder distention presumably causes release of Ach (and other molecules) to stimulate muscarinic receptors on myofibroblasts(predominantly M2). (Mansfield et al 2005) It appears that an increase in Ach release from the urothelium and/or upregulation of muscarinic receptors in the urothelium as well as in suburothelial myofibroblasts may increase afferent nerve activity and contribute to the development of detrusor overactivity. (Koelbl et al, 2009)
