Rationale
The goal of RT1 is to present to the ICS community the most up-to-date knowledge on the innervation and physiological interactions of the key components of the urinary tract from the kidney to the bladder. The urinary tract functions to convey urine from the kidneys for storage and intermittent voiding when socially acceptable. RT1 will highlight features of the different components of the tract that allow such an integrated activity and provide a basis to understand when and how pathologies in storage and voiding occur.

9:00 Anthony Kanai (Pharmacologist and Chair, USA)—Bladder Wall
The bladder facilitates low pressure storage of urine until it is convenient to void and consists of three distinct layers; urothelium, lamina propria, and detrusor smooth muscle. The highly innervated transitional urothelium has barrier and neuronal-like properties and communicates bi-directionally with underlying afferent nerves to sense fullness and relay this information to the central nervous system. The lamina propria contains interstitial cells and myofibroblasts to regulate the structural collagen content of the bladder wall to optimize low pressure storage. As micturition is initiated, the detrusor smooth muscle contracts while the circumferential smooth muscle of the bladder neck relaxes and longitudinal urethral smooth muscle contracts to shorten and expand the outlet. Together with relaxation of the external urethral sphincter, urine outflow is optimized.

9:10 Youko Ikeda (Physiologist, USA)—Ureters and Renal Pelvises
The function of the ureter and the associated renal pelvis is to collect urine from nephrons and convey it to the bladder for storage. Urine is transported by ureteric peristalsis, initiated by pacemaker-like cells in the renal pelvis which propagate along the length of the ureter to maintain a wave of contraction behind a bolus of urine. The cellular mechanisms will be discussed in relation to activation of circular and longitudinal smooth muscle layers in the ureteric wall. Structural features are also important in relation to maintenance of a compliant, low pressure, unidirectional flow system, including a specialized luminal epithelium and a uretero-vesical junction.

9:20 Tufan Tarcan (Urologist, Turkey)—Trigone
The trigone forms a unique region of the bladder wall generated by the convergence of endodermal and mesodermal tissues during embryonic development and is delineated by the ureteral orifices and the bladder neck. It is unusual in having a dual function, a synergistic cholinergic/adrenergic innervation and resting spontaneous contractile activity. The mechanisms underlying contractile synergy will be discussed, as well as the role of the trigone in maintaining overall bladder function during the filling and voiding phases of the micturition cycle by exerting variable traction on the ureteric orifices and the bladder neck.

9:30 Marcus Drake (Urologist, UK)—Urethra
The urethra plays a crucial role in both maintaining continence and efficiently expelling urine from the bladder. It also has an important role in sensation as it is densely innervated and has a specialized sensory columnar epithelium that can relay information regarding urine composition or the presence of pathogens. In response, it may induce localized inflammation and/or cholinergic mediated reflex bladder contractions to flush out the urethra. Furthermore, there are sex specific differences in urethral function. In males, during autonomic emission and somatic ejaculation, the smooth muscle of the internal urethral sphincter contracts simultaneously to prevent retrograde ejaculation into the bladder. The discussion will include the anatomy of the male versus female urethrae as well as the physiological role of urethral sensory mechanisms in health and disease.

9:40-10:00 Discussion and Questions—All Speakers