Pelvic Pressure and Tubuloglomerular Feedback in Hydronephrosis

Pediatric acute kidney injury (AKI) is a major cause of morbidity and mortality in children undergoing interventional procedures. The review summarizes current classifications of AKI and acute kidney disease (AKD), as well as systematizes the knowledge on pathophysiology of kidney injury, with a special focus on renal functional reserve and tubuloglomerular feedback. The aim of this review is also to show the state-of-the-art in methods assessing risk and prognosis by discussing the potential role of risk stratification strategies, taking into account both glomerular function and clinical settings conditioned by fluid overload, urine output, or drug nephrotoxicity. The last task is to suggest careful assessment of eGFR as a surrogate marker of renal functional reserve and implementation of point-of-care testing, available in the case of biomarkers like NGAL and [IGFBP-7] × [TIMP-2] product, into everyday practice in patients at risk of AKI due to planned invasive procedures or treatment.

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The influence of ureteral stent on renal pelvic pressure in vivo

Urological Research ◽

10.1007/s00240-009-0199-z ◽

2009 ◽

Vol 37 (4) ◽

pp. 221-225 ◽

Cited By ~ 7

Author(s):

Yi Shao ◽

Zhi-jie Shen ◽

Jian Zhuo ◽

Hai-tao Liu ◽

Sheng-qiang Yu ◽

...

Keyword(s):

Ureteral Stent ◽

Pelvic Pressure

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Nephron blood flow dynamics measured by laser speckle contrast imaging

AJP Renal Physiology ◽

10.1152/ajprenal.00417.2010 ◽

2011 ◽

Vol 300 (2) ◽

pp. F319-F329 ◽

Cited By ~ 34

Author(s):

Niels-Henrik Holstein-Rathlou ◽

Olga V. Sosnovtseva ◽

Alexey N. Pavlov ◽

William A. Cupples ◽

Charlotte Mehlin Sorensen ◽

...

Keyword(s):

Blood Flow ◽

Signal Transmission ◽

Experimental Studies ◽

Flow Dynamics ◽

Laser Speckle ◽

Tubuloglomerular Feedback ◽

Contrast Imaging ◽

Laser Speckle Contrast Imaging ◽

Speckle Contrast ◽

Blood Flow Dynamics

Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50–100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic techniques for extracting the desired data and for examining them for evidence of nephron synchronization. Synchronized TGF oscillations were detected in pairs or triplets of nephrons. The amplitude and the frequency of the oscillations changed with time, as did the patterns of synchronization. Synchronization may take place among nephrons not immediately adjacent on the surface of the kidney.

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The Effect of Irrigation Power and Ureteral Access Sheath Diameter on the Maximal Intra-Pelvic Pressure During Ureteroscopy: In Vivo Experimental Study in a Live Anesthetized Pig

Journal of Endourology ◽

10.1089/end.2019.0317 ◽

2019 ◽

Vol 33 (9) ◽

pp. 725-729 ◽

Cited By ~ 6

Author(s):

Yasser A. Noureldin ◽

Panagiotis Kallidonis ◽

Panteleimon Ntasiotis ◽

Constantinos Adamou ◽

Evangelos Zazas ◽

...

Keyword(s):

Experimental Study ◽

Ureteral Access Sheath ◽

Access Sheath ◽

Pelvic Pressure

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Decrease in ambient [Cl-] stimulates nitric oxide release from cultured rat mesangial cells

AJP Renal Physiology ◽

10.1152/ajprenal.1994.267.1.f190 ◽

1994 ◽

Vol 267 (1) ◽

pp. F190-F195 ◽

Cited By ~ 7

Author(s):

H. Tsukahara ◽

Y. Krivenko ◽

L. C. Moore ◽

M. S. Goligorsky

Keyword(s):

Nitric Oxide ◽

Mesangial Cells ◽

Ionic Composition ◽

Juxtaglomerular Apparatus ◽

Cytosolic Calcium ◽

No Synthase ◽

Tubuloglomerular Feedback ◽

No Production ◽

Rapid Reduction ◽

No Release

It has been hypothesized that fluctuations of the ionic composition in the interstitium of juxtaglomerular apparatus (JGA) modulate the function of extraglomerular mesangial cells (MC), thereby participating in tubuloglomerular feedback (TGF) signal transmission. We examined the effects of isosmotic reductions in ambient sodium concentration ([Na+]) and [Cl-] on cytosolic calcium concentration ([Ca2+]i) in cultured rat MC. Rapid reduction of [Na+] or [Cl-] in the bath induced a concentration-dependent rise in [Ca2+]i. MC are much more sensitive to decreases in ambient [Cl-] than to [Na+]; a decrease in [Cl-] as small as 14 mM was sufficient to elicit a detectable [Ca2]i response. These observations suggest that MC can be readily stimulated by modest perturbations of extracellular [Cl-]. Next, we examined whether activation of MC by lowered ambient [Cl-] influences cellular nitric oxide (NO) production. Using an amperometric NO sensor, we found that a 13 mM decrease in ambient [Cl-] caused a rapid, Ca2+/calmodulin-dependent rise in NO release from MC. This response was not inhibitable by dexamethasone, indicating the involvement of the constitutive rather than the inducible type of NO synthase in MC. In addition, the NO release was blunted by indomethacin pretreatment, suggesting that a metabolite(s) of cyclooxygenase regulates the activation of NO synthase in MC. Our findings that small perturbations in external [Cl-] stimulate MC to release NO, a highly diffusible and rapidly acting vasodilator, provide a possible mechanism to explain the transmission of the signal for the TGF response within the JGA.

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Nonlinear filter properties of the thick ascending limb

AJP Renal Physiology ◽

10.1152/ajprenal.1997.273.4.f625 ◽

1997 ◽

Vol 273 (4) ◽

pp. F625-F634 ◽

Cited By ~ 20

Author(s):

H. E. Layton ◽

E. Bruce Pitman ◽

Leon C. Moore

Keyword(s):

Steady State ◽

Frequency Response ◽

Transit Time ◽

Concentration Profile ◽

Tubuloglomerular Feedback ◽

Thick Ascending Limb ◽

Transport Parameters ◽

Nodal Structure ◽

Nacl Concentration ◽

Fluid Transit Time

A mathematical model was used to investigate the filter properties of the thick ascending limb (TAL), that is, the response of TAL luminal NaCl concentration to oscillations in tubular fluid flow. For the special case of no transtubular NaCl backleak and for spatially homogeneous transport parameters, the model predicts that NaCl concentration in intratubular fluid at each location along the TAL depends only on the fluid transit time up the TAL to that location. This exact mathematical result has four important consequences: 1) when a sinusoidal component is added to steady-state TAL flow, the NaCl concentration at the macula densa (MD) undergoes oscillations that are bounded by a range interval envelope with magnitude that decreases as a function of oscillatory frequency; 2) the frequency response within the range envelope exhibits nodes at those frequencies where the oscillatory flow has a transit time to the MD that equals the steady-state fluid transit time (this nodal structure arises from the establishment of standing waves in luminal concentration, relative to the steady-state concentration profile, along the length of the TAL); 3) for any dynamically changing but positive TAL flow rate, the luminal TAL NaCl concentration profile along the TAL decreases monotonically as a function of TAL length; and 4) sinusoidal oscillations in TAL flow, except at nodal frequencies, result in nonsinusoidal oscillations in NaCl concentration at the MD. Numerical calculations that include NaCl backleak exhibit solutions with these same four properties. For parameters in the physiological range, the first few nodes in the frequency response curve are separated by antinodes of significant amplitude, and the nodes arise at frequencies well below the frequency of respiration in rat. Therefore, the nodal structure and nonsinusoidal oscillations should be detectable in experiments, and they may influence the dynamic behavior of the tubuloglomerular feedback system.

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