Pacemakers in the upper urinary tract.

BACKGROUND: Pacemakers in upper urinary tract (UUT) are still under study. AIM: We reviewed the role of some cells that seem to be involved in the propulsion of urinary bolus from UUT to the bladder. MATERIALS & METHODS: We focuses on evaluating studies on the mechanisms by which the UUT propels urine to the bladder via pacemaker cells. RESULTS: Electric 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. DISCUSSION: Alterations 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. CONCLUSION: These observations open the way for further investigations of this cell type.