Pacemaker process of ureteral peristalsis in multicalyceal kidneys.
The mechanical activity of isolated strips from different areas of the pyeloureteral system was investigated in 10 pigs: calyx, renal pelvis, pyeloureteral junction and ureter. Additionally, electrical activity was measured in some pyeloureteral preparations using the sucrose-gap technique. Regular spontaneous activity with an average frequency of 9.5/min was recorded in calyceal strips, decreasing to 5.4/min in renal pelvis, 5.7/min in pyeloureteral preparations and to 1.2/min in ureteral preparations. The activity of renal pelvis, pyeloureteral and ureteral preparations was less regular, and bursts of fast activity (near 10/min) could be observed in all these preparations. The membrane potential of pyeloureteral strips showed spontaneous generator oscillations of about 10/min. Variations in the pattern of ureteral peristalsis are due to different coupling ratios of membrane potential oscillations to contractions. Adrenaline (10(-5) mol/l) increased the frequency of the oscillations and enhanced their manifestation in the mechanical recordings, whereas tetraethylammonium (5-20 mmol/l) only increased the coupling ratio. The following concept for the generation of ureteral peristalsis in multicalyceal kidneys is developed: several (primary) oscillators exist in the calyces; in the pyeloureteral junction a (secondary) pacemaker exists which has an intrinsic frequency similar to that of the calyceal pacemakers; both processes cooperate in the generation of ureteral peristalsis.
D000818:Animals; D004837:Epinephrine / Q000494:pharmacology; D007365:Intercellular Junctions / Q000502:physiology; D007670:Kidney Calices / Q000502:physiology*; D007682:Kidney Pelvis / Q000502:physiology*; D008564:Membrane Potentials; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D013552:Swine / Q000502:physiology*; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014513:Ureter / Q000502:physiology*
D013757:Tetraethylammonium Compounds; D004837:Epinephrine