Changes in the countercurrent system in the renal papilla: diuresis increases pH and HCO 3 − gradients between collecting duct and vasa recta

1996 ◽  
Vol 432 (6) ◽  
pp. 1062-1068 ◽  
Author(s):  
Gen Kuramochi ◽  
Ulrich Kersting ◽  
Stefan Silbernagl ◽  
William H. Dantzler
Keyword(s):  
Collecting Duct ◽  
Renal Papilla ◽  
Countercurrent System ◽  
Vasa Recta

The vasoconstrictor endothelin system involvement in chronic kidney diseases pathogenesis is now the most often employed treatment method

2021 ◽  
Author(s):  
Moataz Dowaidar
Keyword(s):  
Blood Pressure ◽  
Kidney Diseases ◽  
Collecting Duct ◽  
Treatment Method ◽  
Chronic Kidney Diseases ◽  
System Involvement ◽  
Duct Cells ◽  
Vasa Recta ◽  
Etb Receptor ◽  
Collecting Duct Cells

Over 30,000 publications have been published about the vasoconstrictor endothelin-1, which was identified by Yanagisawa and co-workers in 1988. While the evidence is quite compelling, scientists can only speculate on how the endothelin (ET) system affects blood pressure and renal function at this time. ET system involvement in chronic kidney diseases (CKD) pathogenesis is now the most often employed treatment method. ET1, ET2, and ET3 are all members of the endothelin family. Endothelium, renal, and smooth muscle cells all generate ET-1, a significant isoform found in both cardiovascular and renal systems.Kidney cells act on, and contain, ET-1. The ETA receptor is found in the brain and medulla, but not in the vasa recta or glomeruli. Epithelial and endothelial cells contain the ETB receptor, which is most prominent in collecting duct cells. 3 In several experiments, ET-1 has been established to be largely a preglomerular vasoconstrictor. Mesangial proliferation, contraction, and collagen production are regulated by ET-1 and ETB receptors in podocytes. The epithelium in the collecting duct cells in the medulla is important in controlling Na excretion and BP. Without the ET-1 gene, the mice have hypertension and reduced natriuresis in response to salt loading. Et-1, ETB receptor, and hypertension are shown in mice that have lost the ETB receptor gene. There is no correlation between blood pressure regulation and natriuresis.Combined disruption of the ETA and ETB receptors has greater effects on blood pressure and Na reabsorption than when ETB receptor activity is missing. It appears that the ETB receptor doesn't work until ETB is present. Collecting duct-derived ET receptors reduces the transport of sodium. Src kinase and MAPK1/2 decrease epidermal Na channel (ENaC) function, decreasing water and salt reabsorption. Moreover, inner medullary collecting duct cells and vasa recta-bearing cells will release NO, which decreases sodium transport.

The Renal Pelvis: Machinery That Concentrates Urine in the Papilla

Physiology ◽  
2003 ◽  
Vol 18 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Terry M. Dwyer ◽  
Bodil Schmidt-Nielsen
Keyword(s):  
Renal Pelvis ◽  
Collecting Duct ◽  
Osmotic Gradient ◽  
Elastic Recoil ◽  
Vasa Recta ◽  
Rhythmic Contractions

Two decades ago, Bodil Schmidt-Nielsen and Bruce Graves documented the rhythmic contractions of the renal pelvis in a remarkable video, visually demonstrating how peristaltic waves empty the papilla and how the subsequent elastic recoil draws water from the collecting duct and into the tethered-open ascending vasa recta. Thus a periodic hydrostatic gradient generates an axial osmotic gradient. This review recapitulates the video and offers a link to figures and scenes digitized from the original tape.

scholarly journals Inhibition of calcium signaling in descending vasa recta endothelia by ANG II

2000 ◽  
Vol 278 (4) ◽  
pp. H1248-H1255 ◽  
Author(s):  
Thomas L. Pallone ◽  
Erik P. Silldorff ◽  
Zhong Zhang
Keyword(s):  
Collecting Duct ◽  
No Production ◽  
Vascular Bundles ◽  
Thick Ascending Limb ◽  
Ang Ii ◽  
Vasomotor Tone ◽  
Medullary Thick Ascending Limb ◽  
Vasa Recta ◽  
Medullary Collecting Duct ◽  
Peak Phase

The intracellular calcium ([Ca2+]i) response of outer medullary descending vasa recta (OMDVR) endothelia to ANG II was examined in fura 2-loaded vessels. Abluminal ANG II (10− 8 M) caused [Ca2+]i to fall in proportion to the resting [Ca2+]i ( r =0.82) of the endothelium. ANG II (10− 8 M) also inhibited both phases of the [Ca2+]i response generated by bradykinin (BK, 10− 7 M), 835 ± 201 versus 159 ± 30 nM (peak phase) and 169 ± 26 versus 103 ± 14 nM (plateau phase) (means ± SE). Luminal ANG II reduced BK (10− 7 M)-stimulated plateau [Ca2+]i from 180 ± 40 to 134 ± 22 nM without causing vasoconstriction. Abluminal ANG II added to the bath after luminal application further reduced [Ca2+]i to 113 ± 9 nM and constricted the vessels. After thapsigargin (TG) pretreatment, ANG II (10− 8 M) caused [Ca2+]i to fall from 352 ± 149 to 105 ± 37 nM. This effect occurred at a threshold ANG II concentration of 10− 10 M and was maximal at 10− 8 M. ANG II inhibited both the rate of Ca2+ entry into [Ca2+]i-depleted endothelia and the rate of Mn2+ entry into [Ca2+]i-replete endothelia. In contrast, ANG II raised [Ca2+]i in the medullary thick ascending limb and outer medullary collecting duct, increasing [Ca2+]i from baselines of 99 ± 33 and 53 ± 11 to peaks of 200 ± 47 and 65 ± 11 nM, respectively. We conclude that OMDVR endothelia are unlikely to be the source of ANG II-stimulated NO production in the medulla but that interbundle nephrons might release Ca2+-dependent vasodilators to modulate vasomotor tone in vascular bundles.

Localization of the CHIP28 water channel in rat kidney

1992 ◽  
Vol 263 (6) ◽  
pp. C1225-C1233 ◽  
Author(s):  
I. Sabolic ◽  
G. Valenti ◽  
J. M. Verbavatz ◽  
A. N. Van Hoek ◽  
A. S. Verkman ◽  
...  
Keyword(s):  
Plasma Membranes ◽  
Collecting Duct ◽  
Rat Kidney ◽  
Water Channel ◽  
Integral Membrane Protein ◽  
Cortical Collecting Duct ◽  
Basolateral Membranes ◽  
Vasa Recta ◽  
Weak Staining ◽  
Relationship Of

CHIP28 is an integral membrane protein that has been identified as the erythrocyte water channel and that is also expressed in the kidney. Antibodies against erythrocyte CHIP28 were used to localize this protein along the rat urinary tubule. By Western blotting, CHIP28 was detected in kidney plasma membrane and endosome fractions. With the use of immunocytochemistry, CHIP28 was located in brush-border and basolateral plasma membranes of the proximal tubule. The initial S1 segment was weakly stained, but the S2 and S3 segments were heavily labeled. Subapical vesicles were also positive. Apical and basolateral membranes of the long thin descending limb were strongly labeled, but ascending thin and thick limbs of Henle and distal convoluted tubules were negative. Some vasa recta profiles in the medulla were positive. CHIP28 is, therefore, present in membranes with a high constitutive water permeability, where it probably acts as a transmembrane water-conducting channel. Finally, a weak staining of apical and basolateral membranes of cortical collecting duct principal cells was detectable, suggesting a potential relationship of CHIP28 to the vasopressin-sensitive water channel.

scholarly journals Three-dimensional architecture of inner medullary vasa recta

2006 ◽  
Vol 290 (6) ◽  
pp. F1355-F1366 ◽  
Author(s):  
Thomas L. Pannabecker ◽  
William H. Dantzler
Keyword(s):  
Collecting Duct ◽  
Rat Kidney ◽  
Three Dimensional ◽  
Osmotic Gradient ◽  
Graphical Modeling ◽  
Vasa Recta ◽  
Countercurrent Exchange ◽  
Modeling Software ◽  
Specific Proteins ◽  
Thin Limb

The manner in which vasa recta function and contribute to the concentrating mechanism depends on their three-dimensional relationships to each other and to tubular elements. We have examined the three-dimensional architecture of vasculature relative to tubular structures in the central region of rat kidney inner medulla from the base through the first 3 mm by combining immunohistochemistry and semiautomated image acquisition techniques with graphical modeling software. Segments of descending vasa recta (DVR), ascending vasa recta (AVR), descending thin limb (DTL), ascending thin limb (ATL), and collecting duct (CD) were identified with antibodies against segment-specific proteins associated with solute and water transport (urea channel B, PV-1, aquaporin-1, ClC-K1, aquaporin-2, respectively) by immunofluorescence. Results indicate: 1) DVR, like DTLs, are excluded from CD clusters that we have previously shown to be the organizing element for the inner medulla; 2) AVR, like ATLs, are nearly uniformly distributed transversely across the entire inner medulla outside of and within CD clusters; 3) DVR and AVR outside CD clusters appear to be sufficiently juxtaposed to permit good countercurrent exchange; 4) within CD clusters, about four AVR closely abut each CD, surrounding it in a highly symmetrical fashion; and 5) AVR abutting each CD and ATLs within CD clusters form repeating nodal interstitial spaces bordered by a CD on one side, one or more ATLs on the opposite side, and one AVR on each of the other two sides. These relationships may be highly significant for both establishing and maintaining the inner medullary osmotic gradient.

scholarly journals High salt induces autocrine actions of ET-1 on inner medullary collecting duct NO production via upregulated ETB receptor expression

2016 ◽  
Vol 311 (2) ◽  
pp. R263-R271 ◽  
Author(s):  
Kelly Anne Hyndman ◽  
Courtney Dugas ◽  
Alexandra M. Arguello ◽  
Traci T. Goodchild ◽  
Kathleen M. Buckley ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Collecting Duct ◽  
High Salt ◽  
Receptor Expression ◽  
Electrolyte Balance ◽  
No Production ◽  
Inner Medullary Collecting Duct ◽  
Nitrite Production ◽  
Vasa Recta ◽  
Medullary Collecting Duct

The collecting duct endothelin-1 (ET-1), endothelin B (ETB) receptor, and nitric oxide synthase-1 (NOS1) pathways are critical for regulation of fluid-electrolyte balance and blood pressure control during high-salt feeding. ET-1, ETB receptor, and NOS1 are highly expressed in the inner medullary collecting duct (IMCD) and vasa recta, suggesting that there may be cross talk or paracrine signaling between the vasa recta and IMCD. The purpose of this study was to test the hypothesis that endothelial cell-derived ET-1 (paracrine) and collecting duct-derived ET-1 (autocrine) promote IMCD nitric oxide (NO) production through activation of the ETB receptor during high-salt feeding. We determined that after 7 days of a high-salt diet (HS7), there was a shift to 100% ETB expression in IMCDs, as well as a twofold increase in nitrite production (a metabolite of NO), and this increase could be prevented by acute inhibition of the ETB receptor. ETB receptor blockade or NOS1 inhibition also prevented the ET-1-dependent decrease in ion transport from primary IMCDs, as determined by transepithelial resistance. IMCD were also isolated from vascular endothelial ET-1 knockout mice (VEETKO), collecting duct ET-1 KO (CDET-1KO), and flox controls. Nitrite production by IMCD from VEETKO and flox mice was similarly increased twofold with HS7. However, IMCD NO production from CDET-1KO mice was significantly blunted with HS7 compared with flox control. Taken together, these data indicate that during high-salt feeding, the autocrine actions of ET-1 via upregulation of the ETB receptor are critical for IMCD NO production, facilitating inhibition of ion reabsorption.

scholarly journals Axial compartmentation of descending and ascending thin limbs of Henle's loops

2013 ◽  
Vol 304 (3) ◽  
pp. F308-F316 ◽  
Author(s):  
Kristen Y. Westrick ◽  
Bradley Serack ◽  
William H. Dantzler ◽  
Thomas L. Pannabecker
Keyword(s):  
Blood Vessels ◽  
Water Permeability ◽  
Collecting Duct ◽  
Osmotic Gradient ◽  
Loop Length ◽  
Vasa Recta ◽  
Pass Through ◽  
Solute Gradient ◽  
Radial Organization

In the inner medulla, radial organization of nephrons and blood vessels around collecting duct (CD) clusters leads to two lateral interstitial regions and preferential intersegmental fluid and solute flows. As the descending (DTLs) and ascending thin limbs (ATLs) pass through these regions, their transepithelial fluid and solute flows are influenced by variable transepithelial solute gradients and structure-to-structure interactions. The goal of this study was to quantify structure-to-structure interactions, so as to better understand compartmentation and flows of transepithelial water, NaCl, and urea and generation of the axial osmotic gradient. To accomplish this, we determined lateral distances of AQP1-positive and AQP1-negative DTLs and ATLs from their nearest CDs, so as to gauge interactions with intercluster and intracluster lateral regions and interactions with interstitial nodal spaces (INSs). DTLs express reduced AQP1 and low transepithelial water permeability along their deepest segments. Deep AQP1-null segments, prebend segments, and ATLs lie equally near to CDs. Prebend segments and ATLs abut CDs and INSs throughout much of their descent and ascent, respectively; however, the distal 30% of ATLs of the longest loops lie distant from CDs as they approach the outer medullary boundary and have minimal interaction with INSs. These relationships occur regardless of loop length. Finally, we show that ascending vasa recta separate intercluster AQP1-positive DTLs from descending vasa recta, thereby minimizing dilution of gradients that drive solute secretion. We hypothesize that DTLs and ATLs enter and exit CD clusters in an orchestrated fashion that is important for generation of the corticopapillary solute gradient by minimizing NaCl and urea loss.

Basic amino acid transport in renal papilla: microinfusion of Henle's loops and vasa recta

1993 ◽  
Vol 265 (6) ◽  
pp. F830-F838 ◽  
Author(s):  
W. H. Dantzler ◽  
S. Silbernagl
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Basic Amino Acid ◽  
Renal Papilla ◽  
Tubular Structures ◽  
Acid Transport ◽  
Basic Amino Acids ◽  
Neutral Amino Acids ◽  
Vasa Recta

To determine whether basic amino acids, like acidic and neutral amino acids, could be reabsorbed distal to tips of Henle's loops and recycled between loops and vasa recta in the renal papilla, we continuously microinfused ascending Henle's loops and vasa recta with 14C-labeled L-lysine (L-Lys; 1.28 mM) or L-arginine (L-Arg; 1.17 mM) and 3H-labeled inulin. We also determined percent of recovered radiolabel as intact amino acid. Like acidic and neutral amino acids, relative to inulin, approximately 30% of L-Lys and approximately 45% of L-Arg microinfused into Henle's loops were reabsorbed. However, whereas radiolabeled L-Lys reabsorption, like reabsorption of acidic and neutral amino acids, was not readily inhibited, radiolabeled L-Arg reabsorption was reduced to approximately 25% by addition of unlabled L-Arg (50 mM) or L-homoarginine (L-Homo-Arg) (50 mM) to infusate. This observation provides greater evidence for specific, carrier-mediated reabsorption for L-Arg than for acidic or neutral amino acids. About 36% (relative to inulin) of each of these amino acids microinfused into ascending vasa recta apparently was transferred directly into ipsilateral tubular structures (probably thin descending limbs of Henle's loops). Transfer of radiolabeled L-Arg was reduced to approximately 8% by the inclusion of unlabeled L-Arg (50 mM) in infusate. Transfer of unlabeled L-Lys was unaffected by inclusion of unlabeled L-Lys (50 mM) in infusate but was reduced to approximately 20% by inclusion of unlabeled L-Arg (50 mM) or L-Homo-Arg (50 mM) in infusate. (ABSTRACT TRUNCATED AT 250 WORDS)

Urea flux in the ureter

1988 ◽  
Vol 255 (2) ◽  
pp. F244-F249 ◽  
Author(s):  
B. L. Walser ◽  
Y. Yagil ◽  
R. L. Jamison
Keyword(s):  
Water Movement ◽  
Collecting Duct ◽  
Urine Flow ◽  
Urea Concentration ◽  
Renal Papilla ◽  
Distal Ureter ◽  
Urea Reabsorption

It has been hypothesized that urea from the final urine is recycled into the renal papilla through the pelvic epithelium. To test this hypothesis, samples of urine were collected by micropuncture proximally and distally through the intact, contracting ureter of the anesthetized rat. In 12 rats, in which urine flow was 5.89 +/- 0.67 microliter/min (a moderate antidiuresis), the ratio of proximal-to-distal urea concentration, corrected for water movement, was 0.93 +/- 0.03 (P less than 0.01 compared with unity), indicating that approximately 7% of urea in the urine emerging from the terminal collecting duct was reabsorbed by the time it reached the distal ureter. To assess the possible contribution of urea reabsorption by the ureter, the ureter was cannulated proximally and distally and perfused with urine of known composition at 6.26 +/- 0.10 microliter/min. In nine rats, the ratio of urea concentration in the perfusate collected from the distal end of the ureter to that in the perfusate entering the proximal end was 0.93 +/- 0.02 (P less than 0.01 compared with unity), indicating 7% reabsorption. Movement of solute across the ureteral epithelium was not restricted to urea. Potassium and creatinine were also reabsorbed [3.4 +/- 0.9 (P less than 0.01) and 3.5 +/- 1.2% (P less than 0.05), respectively], whereas sodium was secreted [9.2 +/- 2.3% (P less than 0.01)].(ABSTRACT TRUNCATED AT 250 WORDS)

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