Frequency gradient in the autorhythmicity of the pyeloureteral pacemaker system

Constantinou, Christos E.; Neubarth, Janina; M, Mensah-Dwumah

doi:10.1007/bf01936991

Cited by 26 publications

(15 citation statements)

References 7 publications

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“…The fact that the periodicity coincides with ureteral peristaltic contractions and is abolished when the ureter is paralyzed, strongly suggests that the periodic closure of the terminal collecting duct is due to peristalsis of the pelvic ureter. Moreover, it is likely a widespread phenomenon occurring in man and other species (9,17). Reinking and Schmidt-Nielsen (9) proposed that ureteral peristalsis enhances processes that increase urinary osmolality by exerting a milking action on the papilla, thereby interrupting, among other things, urinary flow in the collecting ducts and blood flow in the vasa recta.…”

Section: Discussionmentioning

confidence: 99%

Urinary Concentration in the Papillary Collecting Duct of the Rat

Oliver¹,

Roy²,

Jamison³

1982

J. Clin. Invest.

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A B S T R A C T Urine was observed to flow intermittently in the collecting ducts of the extrarenal papilla of antidiuretic rats. The purpose of this investigation was to test Reinking and Schmidt-Nielsen's hypothesis that intermittent flow plays an important role in the production of maximally concentrated urine. Samples of collecting duct fluid were obtained from the base and tip of the papilla by micropuncture through the intact ureter. Fluid osmolality rose sharply from base, 894±120 mosmol/kg H20-' (mean±SE), to tip, 1,667±114 (P<0.001), a distance of only 2 mm, and was due exclusively to reabsorption of water. After excision of the ureter, which abolished intermittent flow, osmolality fell modestly at the base to 723±82 mosmol/kg H20-' (P < 0.02), but strikingly at the tip to 1,012±103 (P < 0.001). The pelvic ureter was paralyzed by topical verapamil and dimethylsulfoxide, which abolished intermittent flow. Osmolality of urine at the tip was not changed (1,959±184 mosmol/kg H20-1 before, vs. 1,957±126 after paralysis). The ureter was severed just beyond the papillary tip, a maneuver which preserved intermittent flow but abolished urinary reflux over the papilla. Urinary osmolality fell from 1,876±134 mosmol/kg H20-1 to 1,284±115 (P < 0.005). These findings demonstrate that when the ureter is intact, over half of the increase in urinary osmolality above isotonicity occurs in the terminal onefourth of the medullary collecting duct and is due exclusively to water reabsorption (no net solute addition). It is the continuity of the ureter, rather than intermittent flow due to ureteral peristalsis, which is essential for the formation of a maximally concentrated urine.

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Section: Discussionmentioning

confidence: 99%

Urinary Concentration in the Papillary Collecting Duct of the Rat

Oliver¹,

Roy²,

Jamison³

1982

J. Clin. Invest.

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“…Rather it suggests that one pacemaker region in the proximal portion of the UUT dominates to drive neighbouring regions and that conduction block is a dynamic process and modulated by a number of factors such as wall stress or the hormonal/neurotransmitter/ prostaglandin milieu. These mechanisms remain largely unknown but may well be evoked to explain the conduction block between the renal pelvis and the ureter evident in vivo under conditions of low urine production which is relieved during periods of increased diuresis [8,9,11,40,44,45,[53][54][55].…”

Section: Electrical Recordings From Smc Of the Uutmentioning

confidence: 99%

Interstitial cell of Cajal-like cells in the upper urinary tract

Lang

Klemm

2005

J Cellular Mol Med

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Autorhythmicity in the upper urinary tract (UUT) has long been considered to arise in specialized atypical smooth muscle cells (SMC) predominately situated in the most proximal regions of the pyeloureteric system. These atypical SMC pacemakers have been thought to trigger adjacent electrically-quiescent typical SMC to fire action potentials which allow an influx of Ca 2+ and the generation of muscle contraction. More recently, the presence of cells with many of the morphological, electrical and immunohistochemical characteristics of interstitial cells of Cajal (ICC), the pacemaker cells of the gastrointestinal tract, have been located in many regions of both the upper and lower urinary tract. This article reviews the evidence from the literature and from our laboratory supporting a role of both atypical SMC and ICC-like cells in the initiation and propagation of pyeloureteric peristalsis in the UUT. We propose a new model in which there are 2 populations of pacemaker cells, high frequency atypical SMC and lower frequency ICC-like cells, both of which can drive electrically-quiescent typical SMC. The relative presence of these 2 populations of pacemaker cells and the relatively-long refractoriness of typical SMC determines the decreasing frequency of contraction with distance from the renal fornix. In the absence of the proximal pacemaker drive from atypical SMC after pyeloureteral/ureteral obstruction or surgery, ICC-like cell pacemaking provides a compensatory mechanism allowing the ureter to maintain rudimentary peristaltic waves and movement of urine from the pyelon towards the bladder.

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“…Furthermore, whether there is a frequency gradient within the calyceal length remains the subject of further investiga tion. However, there is evidence (1,6) within the unicalyceal system of the rabbit and the dog that segmentation of the renal pelvis into strips produces a frequency gradient. It may be hypothesized that the structural integration of pacemaking cells responsible for the rhythmic activity of pyeloureteral smooth muscle pos sesses an organization which ensures a gradient of excitability.…”

Section: Discussionmentioning

confidence: 99%

Hydronephrotic Alterations in Calyceal and Renal Pelvic Pacemaker Function of thein vitroPyeloureteral System

M¹,

Djurhuus²,

Constantinou³

1980

Urol Int

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There are regional variations of the amplitude, frequency and waveform of spontaneous contractions within the isolated renal pelvis and calyx of the multicalyceal pyeloureter of the pig. The contractility of these structures was studied in normal and hydronephrotic preparations. Tissues were obtained from normal and chronically obstructed animals. In 20 normal preparations, the contractile frequency of the renal pelvis was 4.9 ± 2.1 contractions/min, while that of the calyx was 9.5 ± 2.2 (mean ± SD). The recorded amplitude was 0.95 ± 0.92 and 0.45 ± 0.61 g, respectively. The waveform of the calyceal contractility approximated the sinusoid demonstrating a slow rise and fall in tension, while the waveform of renal pelvic smooth muscle demonstrated a faster increase in tension. Obstruction and hydronephrosis produced a minimal alteration in the frequency and amplitude of the calyceal structures, 9.1 ± 2.2 contractions/min and 0.71 ± 0.49 g, respectively. Hydronephrotic renal pelves demonstrated a significant increase in the frequency of spontaneous contractility 8.0 ± 4.2 contractions/min with no change in the mean amplitude of contraction 0.88 ± 0.90 g. These data suggest that obstruction alters the frequency of isolated renal pelvic contraction so that they approximate the frequency of isolated calyceal contractions.

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Frequency gradient in the autorhythmicity of the pyeloureteral pacemaker system

Cited by 26 publications

References 7 publications

Urinary Concentration in the Papillary Collecting Duct of the Rat

Urinary Concentration in the Papillary Collecting Duct of the Rat

Interstitial cell of Cajal-like cells in the upper urinary tract

Hydronephrotic Alterations in Calyceal and Renal Pelvic Pacemaker Function of thein vitroPyeloureteral System

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