Pacemakers in the upper urinary tract

Abstract

BackgroundPacemakers in upper urinary tract (UUT) are still under study.AimWe reviewed the role of some cells that seem to be involved in the propulsion of urinary bolus from UUT to the bladder. Materials & MethodsWe focuses on evaluating studies on the mechanisms by which the UUT propels urine to the bladder via pacemaker cells.ResultsElectric active pacemaker cells generate pyeloureteric autorhythmicity driving adjacent smooth muscle cells (SMCs); it emphasizes the role of the interstitial cells of Cajal‐like cells (ICC‐LCs) localized in the UUT. Interstitial cells of Cajal (ICCs) are now thought to cooperate in conducting and amplifying pacemaker activity in the UUT. These cells produce electrical slow‐wave potentials and determine the propagation of peristaltic activity. Identification of ICC‐LCs is facilitated by use of c‐kit antibodies. Contraction waves arising from the UUT and the propagation of these waves may require the direct involvement of ICC‐LCs, as c‐kit immunoreactivity appears developmentally at the same time as coordinated unidirectional peristaltic contraction. ICC‐LCs observed in the UUT have morphological features similar to those of c‐kitpositive ICCs in the gastrointestinal tract. In addition to gastrointestinal motility, ICCs may also play a significant role in the propagation, coordination, and modulation of ureteropelvic peristalsis.DiscussionAlterations in ICC‐LCs are closely associated with a variety of motility disorders and many congenital urological diseases of the UUT such as primary obstructive megaureter, congenital ureteropelvic junction obstruction, and vesicoureteral reflux.ConclusionThese observations open the way for further investigations of this cell type. Neurourol. Urodynam. 32: 349–353, 2013. © 2012 Wiley Periodicals, Inc.

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“…In the proximal ureter, electric active pacemaker cells generate pyeloureteric rhythmicity driving adjacent smooth muscle cells thus emphasizing the role of the interstitial cells of Cajal-like cells localized at this level [15]. These cells are involved in conducting and amplifying pacemaker activity in the upper urinary tract, producing electrical slow-wave potentials favouring the propagation of ureteral peristaltic activity [15].…”

“…In the proximal ureter, electric active pacemaker cells generate pyeloureteric rhythmicity driving adjacent smooth muscle cells thus emphasizing the role of the interstitial cells of Cajal-like cells localized at this level [15]. These cells are involved in conducting and amplifying pacemaker activity in the upper urinary tract, producing electrical slow-wave potentials favouring the propagation of ureteral peristaltic activity [15]. In the distal ureter and ureterovesical junction, in contrast, there is a rich network of autonomic nerve fibers and numerous ganglion cells that play an important role in the coordination of the ureter and bladder activity at the ureterovesical junction [13],[14],[16].…”

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“…ICC-LC are electrically active and responsible for conduction of slow-wave potentials for peristaltic movements [40]. Contraction waves generated in the renal pelvis are probably propagated, coordinated and modulated in the upper urinary tract by ICC-LC [41,42]. ICCs, thanks to their automatism, are able to replace discontinued atypical SMCs impulses and maintain peristaltis of lower ureter parts [40,43].…”

Physiopathology of vesico-ureteral reflux

“…Such cells were identified by immunostaining for the c-kit protooncogene at the cell membrane. The ICCs are cells considered as responsible for pacemaker activity in the human ureter, and coordinating ureteric motility [13–15]. These cells produce electrical slow-wave potential and propagate peristaltic activity.…”