Organization and function of ICC in the urinary tract

Abstract

ICC are found in both the upper and lower urinary tract. They are not found in the ureter itself but are confined to the lamina propria of the renal pelvis and pelvi-calyceal junction. They do not appear to have a primary pacemaker role (this is ascribed to atypical smooth muscle cells in the same location) but rather conduct and amplify the pacemaker signals generated by the atypical smooth muscle cells. In the bladder, ICC are widely distributed in the sub-urothelial region, in the lamina propria and at the margins of the detrusor smooth muscle bundles. Again they appear not to have a pacemaking role and such evidence as there is would suggest that they have a role in the modulation of signal transduction. The strongest evidence that ICC in the urinary tract act as pacemakers comes from studies of those in the urethra. Isolated ICC show regular spontaneous depolarizations in current clamp which resemble very closely the slow waves recorded from intact tissue. In voltage clamp they show abundant calcium-activated chloride current and spontaneous transient inward currents which can be blocked by chloride channel blockers. However, their role in the modulation of urethral tone has yet to be fully elucidated.

Rho-associated kinase plays a role in rabbit urethral smooth muscle contraction, but not via enhanced myosin light chain phosphorylation

“…On the other hand, during voiding, the urethra relaxes and the detrusor contracts to facilitate emptying of the bladder (36). An isolated rat urethral preparation is "continent" in the absence of external neural input, but flow ensues when the smooth muscle is relaxed (29). Furthermore, stimulation of the skeletal muscle makes remarkably little difference to the ability of the contracted urethra to retain fluid.…”

C-kit receptor in the human vas deferens: distinction of mast cells, interstitial cells and interepithelial cells

“…The existence of CLC in the upper and lower urinary tract has been clearly shown before (Hashitani 2006, McHale et al 2006, Lang et al 2007). The present study revealed numerous IC that did not form a clear network.…”

The electrical activity of the bladder after isolation

“…Мочевой пузырь большую часть времени функционального цикла ведет себя как орган кумуляции мочи, при этом в различных областях мышечного слоя наблюдается аналогичный электрический базовый ритм. В этом же временном интервале уретра контрактирует препятствуя утечке мочи и создавая тем самым условия для продолжительного мышечного тонуса [6,13]. Фаза опорожнения мочевого пузыря, обеспечиваемая синхронизацией пейсмекеров детрузор (мышечные слои) для формирования перистальтики органа, сопровождается кратковременной релаксацией мышц уретры [8,14].…”