Recent evidence suggests the neurotransmitter nitric oxide (NO) may be involved in a variety of functions in the lower urinary tract and in a number of voiding disorders. Preliminary data indicate that NO can be released from the urothelium as well as afferent nerves by various stimuli raising the possibility that the urothelium is involved in intercellular signaling in the urinary bladder. It has been suggested that alterations in NO levels may influence afferent excitability as well as urothelial membrane function. Elucidation of factors and mechanisms controlling acute and/or chronic NO release in the urinary bladder may provide fundamental insights into the pathology of bladder dysfunction. The proposed experiments will use new methods such as cultured urothelial cells and a selective NO porphyrinic microsensor to examine the role of NO in neural-epithelial interactions in the urinary bladder. Aim #1 will evaluate whether urothelial cells may be involved in intercellular chemical signaling or communication and also whether nerve may regulate the signaling factors released from the epithelium. The location of afferent nerves next to the urothelium suggests that urothelial cells might be targets for transmitters released from bladder nerves. Aim #2 will determine if altered NO concentration alters bladder function by affecting the properties of bladder nerves and/or disrupting the urothelial barrier. We will evaluate the effect of NO on epithelial function (changes in transepithelial resistance or permeability) in addition to using c-fos (as a monitor of afferent activity) to determine the involvement of afferents in the effect of NO on bladder function. Aim 3 will evaluate effect of pathology on neural-epithelial interactions and NO release from the lower urinary tract. Alterations in NO levels may affect excitability of sensory nerves in the bladder as well as adversely affect the epithelium, increasing permeability to toxic substances that may contribute to loss of membrane barrier integrity associated with certain diseases. Thus, selective pharmacologic interventions aimed at altering NO levels could provide a new approach to our understanding and clinical management of bladder disorders.