A network thermodynamic model of salt and water flow across the kidney proximal tubule

1978 ◽  
Vol 235 (6) ◽  
pp. F638-F648 ◽  
Author(s):  
S. R. Thomas ◽  
D. C. Mikulecky
Keyword(s):  
Proximal Tubule ◽  
Water Flow ◽  
Thermodynamic Model ◽  
Circuit Simulation ◽  
Basolateral Membrane ◽  
Kidney Proximal Tubule ◽  
Network Analyses ◽  
Pump Rate ◽  
Parameter Values ◽  
The Given

This network thermodynamic model of kidney proximal tubule epithelium treats coupled salt and water flow across each component membrane of the epithelium. We investigate the effects of various relative internal parameter values on the concentration of transepithelial flow, the concentrations in the cell and interspace, and the distribution of flows between cellular and paracellular routes. Best fit is obtaine if the apical and basolateral membrane reflection coefficients (or) are equal. The measured transepithelial filtration coefficient, Lp, is a function not only of the component Lps but also of the internal concentrations, or's, and permeabilities. For the given system topology (i.e., connectedness), parameters of component membranes must be within a narrow range to be consistent with experimental results. The dependence of the concentration of transported fluid on the balance between the solute pump rate and the transepithelial volume flow driving force is shown. This has implications for the effects of peritubular or lumen oncotic pressure on salt and water flow. With Appendix B of this paper and a user's guide for a circuit-simulation package (e.g., SPICE or PCAP) the reader can perform similar network analyses of transport models himself.

A network thermodynamic model of salt and water flow across the kidney proximal tubule

1979 ◽  
Vol 237 (6) ◽  
pp. F489-F489
Author(s):  
S. R. Thomas ◽  
D. C. Mikulecky
Keyword(s):  
Proximal Tubule ◽  
Water Flow ◽  
Thermodynamic Model ◽  
Program Listing ◽  
Kidney Proximal Tubule

Page F638: S. R. Thomas and D. C. Mikulecky. “A network thermodynamic model of salt and water flow across the kidney proximal tubule.” Page F640: In equation 4, (c12 – 2c1c2 + c22) should be (c22 – c12)/2. Page 646: In the program listing of Fig. 4 the line 00320 RJS3 1 6 2.457E4 should read instead 00320 RJS3 11 16 2.457E4.

Effect of norepinephrine on intracellular pH in kidney proximal tubule: role of Na+-( HCO 3 − ) n cotransport

1998 ◽  
Vol 275 (1) ◽  
pp. F33-F45 ◽  
Author(s):  
Solange Abdulnour-Nakhoul ◽  
Raja N. Khuri ◽  
Nazih L. Nakhoul
Keyword(s):  
Membrane Potential ◽  
Proximal Tubule ◽  
Intracellular Ph ◽  
Basolateral Membrane ◽  
Inhibitory Effect ◽  
Rate Of Change ◽  
Kidney Proximal Tubule ◽  
Luminal Membrane ◽  
Basolateral Membrane Potential

We examined the effect of norepinephrine (NE) on intracellular pH (pHi) and activity of Na+([Formula: see text]) in the isolated perfused kidney proximal tubule of Ambystoma, using single-barreled voltage and ion-selective microelectrodes. In control[Formula: see text] Ringer, addition of 10−6 M NE to the bath reversibly depolarized the basolateral membrane potential ( V 1), the luminal membrane potential ( V 2), and the transepithelial potential difference ( V 3) and increased pHi by 0.14 ± 0.02. These effects were mimicked by isoproterenol but were abolished after pretreatment with SITS or in the absence of CO2/[Formula: see text]. Removal of bath Na+ depolarized V 1 and V 2, hyperpolarized V 3, and decreased pHi. These effects are largely mediated by the electrogenic Na+-([Formula: see text]) n cotransporter. In the presence of NE, the effects of Na+ removal on membrane potential differences and the rate of change of pHi were significantly smaller. Reducing bath [Formula: see text] concentration from 10 to 2 mM at constant CO2 (pH 6.8) depolarized V 1 and V 2, decreased pHi, and lowered[Formula: see text]. These changes are also due to Na+-([Formula: see text]) n . In the presence of NE, reducing bath [[Formula: see text]] caused a smaller depolarizations of V 1 and V 2, and the rate of pHi decrease was significantly reduced. Our results indicate: 1) NE causes an increase in pHi; 2) the NE-induced alkalinization is mediated by a SITS-sensitive and[Formula: see text]-dependent transporter on the basolateral membrane; and 3) in the presence of NE, the reduced effects caused by basolateral[Formula: see text] changes or Na+ removal are indicative of an inhibitory effect of NE on Na+-([Formula: see text]) n cotransport.

A dileucine motif targets the sulfate anion transporter sat-1 to the basolateral membrane in renal cell lines

2004 ◽  
Vol 287 (2) ◽  
pp. C365-C372 ◽  
Author(s):  
Ralf R. Regeer ◽  
Daniel Markovich
Keyword(s):  
Fusion Protein ◽  
Proximal Tubule ◽  
Cell Lines ◽  
Renal Cell ◽  
Mdck Cells ◽  
Basolateral Membrane ◽  
Kidney Proximal Tubule ◽  
Dileucine Motif ◽  
Sat 1 ◽  
Renal Cell Lines

The sat-1 transporter mediates sulfate/bicarbonate/oxalate anion exchange in vivo at the basolateral membrane of the kidney proximal tubule. In the present study, we show two renal cell lines [Madin-Darby canine kidney (MDCK) and porcine proximal tubular kidney (LLC-PK1) cells] that similarly target sat-1 exclusively to the basolateral membrane. To identify possible sorting determinants, we generated truncations of the sat-1 cytoplasmic COOH terminus, fused to enhanced green fluorescence protein (EGFP) or the human IL-2 receptor α-chain (Tac) protein, and both fusion constructs were transiently transfected into MDCK cells. Confocal microscopy revealed that removal of the last three residues on the sat-1 COOH terminus, a putative PDZ domain, had no effect on basolateral sorting in MDCK cells or on sulfate transport in Xenopus oocytes. Removal of the last 30 residues led to an intracellular expression for the GFP fusion protein and an apical expression for the Tac fusion protein, suggesting that a possible sorting motif lies between the last 3 and 30 residues of the sat-1 COOH terminus. Elimination of a dileucine motif at position 677/678 resulted in the loss of basolateral sorting, suggesting that this motif is required for sat-1 targeting to the basolateral membrane. This posttranslational mechanism may be important for the regulation of sulfate reabsorption and oxalate secretion by sat-1 in the kidney proximal tubule.

scholarly journals Adenosine deamination to inosine in isolated basolateral membrane from kidney proximal tubule: Implications for modulation of the membrane-associated protein kinase A

2009 ◽  
Vol 486 (1) ◽  
pp. 44-50 ◽  
Author(s):  
Natália Assaife-Lopes ◽  
Mira Wengert ◽  
Ana Acacia de Sá Pinheiro ◽  
Sharon Schilling Landgraf ◽  
Roberto Paes-de-Carvalho ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Proximal Tubule ◽  
Protein Kinase A ◽  
Basolateral Membrane ◽  
Kidney Proximal Tubule ◽  
Adenosine Deamination ◽  
Kinase A

Solvent drag of sucrose during absorption indicates paracellular water flow in the rat kidney proximal tubule

1988 ◽  
Vol 412 (5) ◽  
pp. 541-547 ◽  
Author(s):  
Guillermo Whittembury ◽  
Gerhard Malnic ◽  
Margarida Mello-Aires ◽  
Carlos Amorena
Keyword(s):  
Proximal Tubule ◽  
Water Flow ◽  
Rat Kidney ◽  
Solvent Drag ◽  
Kidney Proximal Tubule ◽  
Paracellular Water Flow

Kidney proximal tubule cells: Epithelial cells without EGTA-extractable annexins?

2000 ◽  
Vol 78 (4) ◽  
pp. 495-502 ◽  
Author(s):  
Sandra Tribolo ◽  
Suzanne Maroux ◽  
Dominique Massey-Harroche
Keyword(s):  
Epithelial Cells ◽  
Proximal Tubule ◽  
Primary Culture ◽  
Collecting Duct ◽  
Basolateral Membrane ◽  
Isolated Cells ◽  
Vesicular Traffic ◽  
Kidney Proximal Tubule ◽  
Annexin I ◽  
Immunofluorescence Labelling

The expression and the subcellular localizations of annexins I, II, IV, VI, and XIII in renal epithelial cells were investigated, using immunological techniques with specific monoclonal antibodies. Upon performing Western blotting experiments, no annexins VI and XIII were detected in kidney, whereas annexins I, II, and IV were. Immunofluorescence labelling procedure performed on thin frozen renal sections showed the presence of these three annexins along the plasma membrane of the collecting duct cells with a restricted expression of annexin I at principal cells. Annexin I was also found present in some glomerular cells. None of these annexins, however, were detected in the proximal tubular cells upon performing immunofluorescence labelling and electrophoretic analysis on an EGTA (ethylenebis(oxyethylenenitrilo)tetraacetic acid)-extractable annexin fraction prepared from freshly isolated cells. This is the first time a mammalian epithelial cell has been found to express non-typical annexin (at least partly solubilized with EGTA). However, when these cells were grown in primary culture, they were found to express annexins I, II, IV, and V. As well as being located along the basolateral membrane, annexins I and II are also present on vesicles, which suggests that these annexins may be involved in vesicular traffic under cell culture conditions.Key words: annexin, kidney, proximal tubule, primary culture.

scholarly journals Non-selective cation channels in basolateral-membrane vesicles from pars recta of rabbit kidney proximal tubule

1990 ◽  
Vol 272 (3) ◽  
pp. 839-842 ◽  
Author(s):  
J Blokkebak-Poulsen ◽  
M I Sheikh ◽  
C Jacobsen
Keyword(s):  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Membrane Vesicles ◽  
Diffusion Potential ◽  
Rabbit Kidney ◽  
Cation Channels ◽  
Basolateral Membrane Vesicles ◽  
Univalent Cations ◽  
Kidney Proximal Tubule ◽  
Pars Recta

The characteristics of 86Rb+ fluxes through conductive channels in basolateral-membrane vesicles isolated from pars recta of rabbit kidney proximal tubule were investigated. In RbCl-, KCl- and NaCl-loaded vesicles a transient and almost equal accumulation of 86Rb+ was observed. The uptakes of 86Rb+ were inhibited to the same extent by 10 mM-BaCl2 in all loadings. The accumulation was driven by an electrical diffusion potential. The 86Rb+ flux was dependent on intravesicular Ca2+. Increasing concentrations of Ca2+ gradually decreased the 86Rb+ uptake. At 10 microM-Ca2+ the radioisotope flux was below 20% of control. The vesicles containing the channel showed very low selectivity among the univalent cations K+, Rb+, Li+, Na+ and choline+.

Cell membrane water permeabilities and streaming currents in Ambystoma proximal tubule

1988 ◽  
Vol 255 (1) ◽  
pp. F188-F203 ◽  
Author(s):  
S. Tripathi ◽  
E. L. Boulpaep
Keyword(s):  
Proximal Tubule ◽  
Water Flow ◽  
Membrane Surface ◽  
Basolateral Membrane ◽  
Rate Of Change ◽  
Epithelial Surface ◽  
Streaming Potentials ◽  
Flow Through ◽  
Intracellular Activities ◽  
Paracellular Pathways

An electrophysiological approach is used to analyze the possible routes of osmotically driven water flow across the isolated perfused Ambystoma proximal tubule. The minimum hydraulic conductivities (Lp) of the cell membranes were estimated from the initial rate of change of intracellular activities of Na+ and K+ in response to a step gradient of 50 or 100 mosmol/kg sucrose. The Lp of the apical membrane is 1.30 X 10(-4) cm.s-1.osM-1 referred to the luminal epithelial surface and 2.45 X 10(-6) cm.s-1.osM-1 when corrected for amplification of the brush border (n = 8). The Lp of the basolateral membrane is 1.42 X 10(-4) cm.s-1.osM-1 referred to the basement membrane surface and 6.39 X 10(-6) cm.s-1.osM-1 when corrected for the amplification of the basal and lateral membranes (n = 5). Transepithelial water flows were generated in either direction by a unilateral step increase of osmolality with 100 mosmol sucrose. Bath-to-lumen flow increased paracellular transepithelial resistance (R3) by 48%; lumen-to-bath flow decreased R3 by only 3%. A bilateral increase in the osmolality of both solutions by 50 mosM had no significant effect on R3. Streaming potentials were observed during trans-epithelial water flow induced by unilateral gradients of sucrose; their polarity, magnitude, site of generation, and insensitivity to change of paracellular resistance are all indicative of water flow through paracellular structures, especially the lateral intercellular spaces. Contrary to earlier suggestions (J. M. Diamond, J. Membr. Biol. 51: 195-216, 1979), these potentials are not primarily diffusion potentials across anion-selective tight junctions resulting from solute polarization in the unstirred layers. Instead, a true electrokinetic basis for these streaming potentials is indicated by their continued presence after deletion of all Cl-. Thus water moves through both cellular and paracellular pathways in this epithelium.

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