title: Pacemaker activity in the upper urinary tract.
abstract: Ureteral peristaltic activity begins with the origin of electrical activity at pacemaker sites. These sites are located in the proximal portion of the urinary collecting system. The 'atypical' smooth muscle cells at these sites fire 'pacemaker' potentials at a frequency higher than the 'driven' action potentials recorded from typical smooth muscle cells. In contrast to typical smooth muscle cells, these atypical pacemaker cells have less than 40% of their cellular area occupied by contractile filaments and demonstrate a sparse immunoreactivity for alpha-smooth muscle actin. Expression of c-Kit, a tyrosine kinase receptor, correlates with the onset of organized ureteral peristalsis in the embryo. Capsaicin-sensitive sensory afferents and the endogenous release of tachykinins and prostaglandins are involved in the maintenance of normal ureteral peristalsis.
authors.affiliation: Section of Urology, Yale University School of Medicine, New Haven, Conneticut 06520-8041, USA. robert.weiss@yale.edu
authors.forename: Robert M
authors.initials: RM
authors.lastname: Weiss
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Tamarkin
authors.forename: Marcia A
authors.initials: MA
authors.lastname: Wheeler
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001683:Biological Clocks / Q000502:physiology*; D004576:Electromyography; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D009130:Muscle, Smooth / Q000294:innervation / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology; D010528:Peristalsis / Q000502:physiology; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics / Q000502:physiology; D014551:Urinary Tract / Q000294:innervation*; D014553:Urinary Tract Physiological Phenomena
chemical_list: D019009:Proto-Oncogene Proteins c-kit