Oxalate transport by proximal tubule of the rabbit kidney

1982 ◽  
Vol 243 (3) ◽  
pp. F271-F275 ◽  
Author(s):  
H. O. Senekjian ◽  
E. J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Bath Temperature ◽  
Rabbit Kidney ◽  
Bathing Solution ◽  
Concentration Gradients ◽  
Oxalate Secretion ◽  
Electrical Gradient ◽  
Net Flux ◽  
Active Transport Process ◽  
Oxalate Transport

Oxalate transport was examined in isolated perfused segments of the proximal tubule of the rabbit. When oxalate was present in a concentration of 10(-5) M in the bathing and perfusing solutions, there was a net secretory flux of oxalate of 36.4 +/- 1.4, 34.7 +/- 4.3, and 20.7 +/- 2.8 x 10(-15) mol . min-1 . mm-1 in the superficial S1, S2, and S3 segments, respectively, at a bath temperature of 37 degrees C. The net secretory flux of oxalate in the juxtamedullary S1 and S2 segments was 12.8 +/- 2.5 and 12.5 +/- 3.6 x 10(-15) mol . min-1 . mm-1, respectively. Cooling to 25 degrees C resulted in a significant decrease in the net flux of oxalate. When oxalate was present in the bathing solution only (10(-5) M), the bath-to-lumen flux of oxalate was not different from the net flux in the superficial and juxtamedullary S2 segments. These studies demonstrate that oxalate undergoes net secretion in the rabbit proximal tubule. This occurs against an electrical gradient, in the absence of concentration gradients, and can be inhibited by cooling, suggesting an active transport process. There is significant internephronal heterogeneity in the proximal tubule for oxalate secretion.

Transport of salicylate in proximal tubule (S2 segment) isolated from rabbit kidney

1988 ◽  
Vol 254 (4) ◽  
pp. F554-F561
Author(s):  
L. Schild ◽  
F. Roch-Ramel
Keyword(s):  
Proximal Tubule ◽  
Transport System ◽  
Concentration Gradient ◽  
Bath Temperature ◽  
Rabbit Kidney ◽  
Luminal Membrane ◽  
Carrier Mediated Transport ◽  
Secretory Transport ◽  
Luminal Ph

The secretory and reabsorptive transport of salicylate was studied in the isolated and perfused rabbit proximal tubule (S2 segment). Salicylate secretion (Jb----lsal) fulfilled the criteria for a carrier-mediated transport system: Jb----lsal was saturable, was reversibly inhibited by probenecid, and occurred against a concentration gradient. The Km and Vmax for this secretory transport were 80 microM and 3,200 fmol.min-1.mm-1, respectively. At luminal pH of 7.4 and 6.6, salicylate reabsorption (Jl----bsal) was low (100 fmol.min-1.mm-1). Jl----bsal was stimulated by increasing the bath PCO2 or by removing basolateral HCO3-; Jl----bsal was inhibited by ethoxyzolamide and by SITS in the bath. Our results indicate that salicylate reabsorption depends on H+ secretion, consistent with reabsorption by simple nonionic diffusion. When salicylate was present in the lumen only, Jl----bsal increased after inhibition of the secretory transport by adding ouabain or probenecid in the bath or by lowering the bath temperature. These results are compatible with luminal recycling of salicylate, and suggest the presence of a mediated secretory transporter located at the luminal membrane.

Electrophysiology of basolateral bicarbonate transport in the rabbit proximal tubule

1986 ◽  
Vol 250 (2) ◽  
pp. F267-F272 ◽  
Author(s):  
B. A. Biagi ◽  
M. Sohtell
Keyword(s):  
Proximal Tubule ◽  
Basolateral Membrane ◽  
Sodium Concentration ◽  
Peak Height ◽  
Rabbit Kidney ◽  
Bicarbonate Transport ◽  
Bathing Solution ◽  
Bicarbonate Concentration ◽  
Constant Ph

Conventional microelectrodes were used to examine the electrogenic pathways for bicarbonate transport across the basolateral membranes of proximal convoluted (PCT) and straight (PST) tubule segments of the rabbit kidney perfused in vitro. When bath bicarbonate concentration was reduced from 22 to 6.6 mM at a constant pH, transient depolarizations lasting several seconds with a peak value of approximately 15 mV were seen in both tubule segments. Acetazolamide (0.1 mM) in the lumen and bath solutions reduced the magnitude and increased the duration fo this response. The final pH of the bathing solution influenced both the peak height and steady-state values of the intracellular potential when bicarbonate concentration was reduced either with constant CO2 or with an increase in CO2. Reducing bath sodium concentration by replacement with either tetramethylammonium or N-methyl-D-glucamine resulted in a sustained depolarization of both PCT and PST cells. This response was inhibited by the addition of 10(-4) M 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS) in the bathing solution. By analogy with bicarbonate transport in rat and amphibian proximal tubules, these data suggest that bicarbonate exit across the basolateral membrane of the rabbit proximal tubule is electrogenic and coupled to sodium and that basolateral bicarbonate exit can be inhibited by both acetazolamide and SITS in the bathing solution.

Rate of formation and composition of absorbate from proximal nephron segments

1984 ◽  
Vol 247 (1) ◽  
pp. F117-F129 ◽  
Author(s):  
D. W. Barfuss ◽  
J. A. Schafer
Keyword(s):  
Mineral Oil ◽  
Rabbit Kidney ◽  
Bathing Solution ◽  
Fluid Absorption ◽  
Na Transport ◽  
Concentration Gradients ◽  
Nephron Segments ◽  
Volume Absorption ◽  
Transepithelial Voltage ◽  
Light Mineral

Proximal convoluted (PCT) and proximal straight (PST) tubules from rabbit kidney were isolated and subsequently perfused under light mineral oil so that absorbate could be collected. Volume absorption rates in both segments were comparable to those observed during conventional perfusion in aqueous bathing solution. However, volume absorption in the PCT was significantly decreased by reduction or elimination of preferentially absorbed solutes from the perfusate. As previously observed in the PST, glucose was actively absorbed by the PCT against concentration gradients of up to 26 mM. In contrast, the Cl- concentration of the PCT absorbate was less than that in the lumen, presumably due to preferential HCO3- absorption. In the PST, the Na+ concentration of the absorbate exceeded that in the lumen and, given the negligible measured transepithelial voltage, active transepithelial Na+ transport was demonstrated. In contrast, in the PCT, when preferentially absorbed solutes were present in the perfusate at normal concentrations, the absorbate Na+ concentration was significantly less than that in the lumen. This low absorbate Na+ concentration may be due to the dilutional effect of more rapid fluid absorption in the presence of the preferentially absorbed solutes. When the concentrations of these solutes in the perfusate were reduced or eliminated, the absorbate Na+ concentration was not significantly different from that in the lumen.

Reduction of Potassium in Kidney Proximal Tubules to Aid in Electron Probe X-Ray Microanalysis of Calcium

1985 ◽  
Vol 43 ◽  
pp. 474-475
Author(s):  
A. LeFurgey ◽  
P. Ingram ◽  
L.J. Mandel
Keyword(s):  
Smooth Muscle ◽  
Proximal Tubule ◽  
Electron Probe ◽  
Clinical Applications ◽  
Proximal Tubules ◽  
Rabbit Kidney ◽  
Target Cells ◽  
X Ray ◽  
Freeze Dried

For quantitative determination of subcellular Ca distribution by electron probe x-ray microanalysis, decreasing (and/or eliminating) the K content of the cell maximizes the ability to accurately separate the overlapping K Kß and Ca Kα peaks in the x-ray spectra. For example, rubidium has been effectively substituted for potassium in smooth muscle cells, thus giving an improvement in calcium measurements. Ouabain, a cardiac glycoside widely used in experimental and clinical applications, inhibits Na-K ATPase at the cell membrane and thus alters the cytoplasmic ion (Na,K) content of target cells. In epithelial cells primarily involved in active transport, such as the proximal tubule of the rabbit kidney, ouabain rapidly (t1/2= 2 mins) causes a decrease2 in intracellular K, but does not change intracellular total or free Ca for up to 30 mins. In the present study we have taken advantage of this effect of ouabain to determine the mitochondrial and cytoplasmic Ca content in freeze-dried cryosections of kidney proximal tubule by electron probe x-ray microanalysis.

1123: Renal Oxalate Transport Depends on Local Carbonic Anhydrase Activity in the Proximal Tubule

2004 ◽  
Vol 171 (4S) ◽  
pp. 296-296
Author(s):  
Michael Straub ◽  
Joséphine Befolo-Elo ◽  
Richard E Hautmann ◽  
Edgar Braendle
Keyword(s):  
Carbonic Anhydrase ◽  
Proximal Tubule ◽  
Carbonic Anhydrase Activity ◽  
Oxalate Transport

Vitamin D3 metabolites increase [Ca2+]i in rabbit renal proximal straight tubule cells

1991 ◽  
Vol 260 (5) ◽  
pp. F757-F763 ◽  
Author(s):  
M. Suzuki ◽  
S. Kurihara ◽  
Y. Kawaguchi ◽  
O. Sakai
Keyword(s):  
Vitamin D ◽  
Proximal Tubule ◽  
Ion Concentration ◽  
Rabbit Kidney ◽  
Vitamin D Metabolites ◽  
Dihydroxyvitamin D3 ◽  
Straight Tubule ◽  
Proximal Straight Tubule ◽  
Tubule Cells ◽  
Free Media

Vitamin D metabolites exert both acute and chronic influences on proximal tubule function. To further evaluate vitamin D action on the kidney, we examined the immediate effects of vitamin D metabolites on cytoplasmic calcium ion concentration [( Ca2+]i), using fura-2 and patch-clamp method in cultured proximal straight tubule cells of rabbit kidney. 1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] and 25-hydroxyvitamin D3 [25(OH)D3] evoked a transient rise in [Ca2+]i, and 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] caused a sustained rise in [Ca2+]i; all effects were dose dependent. [Ca2+]i transient, evoked by 1,25(OH)2D3 alone, was abolished in Ca(2+)-free media. Pretreatment of cells in Ca(2+)-free media with caffeine (4 mM) or ryanodine (1 microM) to deplete Ca2+ store of endoplasmic reticulum or with TMB-8 (5 mM) to block Ca2+ release from storage blunted the effect of 25(OH)D3 on [Ca2+]i but not of 24,25(OH)2D3. Data were also supported by activities of Ca-dependent K channel and show that these three vitamin D metabolites in pharmacological doses increase [Ca2+]i of proximal tubule cells from different sources.

Electrophysiology of salamander proximal tubule. II. Interspace NaCl concentrations and solute-coupled water transport

1986 ◽  
Vol 251 (2) ◽  
pp. F334-F347
Author(s):  
H. Sackin
Keyword(s):  
Low Temperature ◽  
Proximal Tubule ◽  
Water Transport ◽  
Time Course ◽  
Fluid Transport ◽  
Bath Temperature ◽  
Null Point ◽  
Constant Composition ◽  
Nacl Concentration ◽  
Test Concentration

The role of the paracellular interspace in solute-coupled water transport was investigated in isolated perfused salamander (Ambystoma) proximal tubules using a null-point technique to estimate interspace NaCl concentrations. Constant composition of luminal fluid was maintained by rapid (200 nl/min) perfusion of tubules 600,micron or less in length. Inhibition of active transport by a decrease in bath temperature from 22 to 0 degrees C in 400 ms produced rapid depolarizations of both the transepithelial (Vte) and basolateral (Vbl) potential, followed by slower changes in potential that occurred at low temperature. During this period, the time course of Vbl was independent of small changes in bath NaCl concentration, whereas the time course of Vte at low temperature varied from a slow depolarization to a slow repolarization depending on whether the concentration of NaCl in the bath equaled or exceeded that in the perfusate. Absence of a slow change in Vte at low temperature indicated a match between the NaCl concentration of the interspace and the test concentration of NaCl in the bath. Using this technique with 12 tubules, the normal interspace NaCl concentration appeared to be approximately 4% above the NaCl concentration of either the lumen or bath, demonstrating that the interspace of the salamander proximal tubule can function as a local hyperosmotic compartment to facilitate fluid transport between solutions of identical composition.

Immunolocalization of gluco- and mineralocorticoid receptors in rabbit kidney

1991 ◽  
Vol 260 (2) ◽  
pp. C226-C233 ◽  
Author(s):  
N. Farman ◽  
M. E. Oblin ◽  
M. Lombes ◽  
F. Delahaye ◽  
H. M. Westphal ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Distal Tubule ◽  
Interstitial Cells ◽  
Rabbit Kidney ◽  
Cell Compartments ◽  
Corticosteroid Hormones ◽  
Collecting Tubule ◽  
Show Evidence ◽  
Cortical Collecting Tubule

The localization of glucocorticoid receptor (GR) and mineralocorticoid receptor (MR) was determined in the rabbit kidney by immunohistochemistry with the use of a monoclonal, anti-GR antibody and a monoclonal, anti-idiotypic, anti-MR antibody. Immunostaining was performed on serial histological sections from normal and adrenalectomized rabbits. The specificity of immunostaining was assessed for MR by in situ competition studies with steroids and for GR by presaturation of the antibody with GR preparation. Immunostaining by both the anti-MR and the anti-GR antibodies was present in all parts of the distal nephron (beyond proximal tubule) and absent in the glomerulus and proximal tubule. The absence of staining by the anti-GR antibody in the proximal tubule suggests that the effects of glucocorticoids in this structure involve either a GR different from that of distal structures or a non-receptor mediated mechanism of action. MR immunostaining predominates in the distal and all along the collecting tubule in its cortical, medullary, and papillary portions. GR immunostaining was most abundant in the medullary ascending limb and distal tubule. Immunostaining by both antibodies was present in papillary interstitial cells and cells of the epithelium lining the papilla. Fifteen to twenty percent of the cells of the cortical collecting tubule, presumably intercalated cells, were devoid of MR and GR immunostaining. Immunostaining was present in both nuclear and cytoplasmic cell compartments. No clear difference was observed between normal and adrenalectomized rabbits. This study is the first report on renal immunolocalization of GR compared with MR. In addition, we show evidence for new targets for corticosteroid hormones such as papillary interstitial cells and papillary epithelium.

Oxalate secretion in the rat proximal tubule

1981 ◽  
Vol 240 (4) ◽  
pp. F295-F298 ◽  
Author(s):  
T. F. Knight ◽  
S. C. Sansom ◽  
H. O. Senekjian ◽  
E. J. Weinman
Keyword(s):  
Proximal Tubule ◽  
Sodium Cyanide ◽  
Proximal Convoluted Tubule ◽  
Oxalate Concentration ◽  
Oxalate Secretion ◽  
Secretory System ◽  
Rat Proximal Tubule

Simultaneous capillary and luminal microperfusion studies in the proximal convoluted tubule of the rat were performed to examine the transepithelial secretory flux of [14C]oxalate. Increases in the concentration of oxalate in the capillary solution from 0.096 to 4.3 mM resulted in progressively higher rates of oxalate secretion into the lumen. Further increases in the capillary concentration of oxalate indicated a tendency toward a plateau. The inclusion of para-chloromercuribenzoate, sodium cyanide, indanyloxyacetic acid, furosemide, or para-aminohippurate in the capillary solution significantly lowered the secretory flux of oxalate. the addition of probenecid in a concentration of 10(-4) M inhibited oxalate secretion when the oxalate concentration in the capillary solution ranged between 1.1 and 4.3 mM, but did not affect oxalate secretion at higher capillary concentrations of oxalate. These results indicate that oxalate secretion in the rat proximal tubule is an active carrier-mediated process. When considered in conjunction with prior studies, the present investigations suggest the possibility that more than one oxalate secretory system exists in the rat proximal tubule.

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