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  • Renal tubule  (8)
  • Epithelial transport  (6)
  • Sulfate transport  (4)
  • Kidney Micropuncture  (2)
  • 11
    Electronic Resource
    Electronic Resource
    Bidirectional active transport of thiosulfate in the proximal convolution of the rat kidney (1980)
    Springer
    Pflügers Archiv 387 (1980), S. 127-132 
    Details
    ISSN: 1432-2013
    Keywords: Renal tubule ; Thiosulfate transport ; Na+ coupled transport ; Sulfate transport ; Paraaminohippurate transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using the standing droplet method in the late proximal convolution and simultaneous microperfusion of the peritubular capillaries, the zero net flux transtubular concentration difference of thiosulfate at 45 s was determined, the latter being taken as a measure of active thiosulfate transport. Under control conditions, in the presence of Na+, near zero Δc values were observed. When 1 mmol/l carinamide or paraaminohippurate (PAH) were added to the perfusates significant reabsorptive Δc arose. However, when 7.5 mmol/l sulfate was added to the Na+-free secretory Δc values were observed. Tested under Na+-free conditions, the secretory Δc was not influenced by simultaneously present 5 mmol/l of SO 4 2− but was diminished by 50 mmol/l SO 4 2− . PAH (1 mmol/l), carinamide (0.2 mmol/l) and probenecid (1 mmol/l) decreased the secretory Δc by 48, 65 and 48%, respectively. The PAH secretion was not influenced, when thiosulfate or sulfate up to 50 mmol/l was added to both perfusates. Under Na+-free conditions the Δc of thiosulfate in early loops of the proximal convolution is higher than in late loops, while for PAH this pattern is reversed. Taken together with the previously published inhibition of sulfate reabsorption by thiosulfate the data indicate 1. thiosulfate is reabsorved by the Na+-dependent sulfate transport system and 2. thiosulfate is simultaneously secreted by a carinamide-, probenecid-and PAH-sensitive secretory system. The secretory system might also be shared by sulfate. The thiosulfate net flux is the result of the difference in the activity of the counteracting transporters, located at the luminal and contraluminal cell side. Is is possible that the higher activity of the transporter at one cell side leads to a reversal of the flux through the transporter at the other cell side.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584263
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  • 12
    Electronic Resource
    Electronic Resource
    Contraluminal sulfate transport in the proximal tubule of the rat kidney (1985)
    Springer
    Pflügers Archiv 404 (1985), S. 293-299 
    Details
    ISSN: 1432-2013
    Keywords: Epithelial transport ; Contraluminal cell membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study the specificity for the contraluminal sulfate transport system the inhibitory potency of sulfate esters and sulfonate compounds on the35SO 4 2− influx from the interstitium into cortical tubular cells in situ has been determined. The following was found: 1. From 10 sulfate monoesters tested 9 inhibited contraluminal sulfate influx with an app.K i between 0.6 and 6 mmol/l; the two sulfate diesters tested, however, did not. 2. Out of 8 aliphatic sulfonate compounds only three, having a NH- or OH-group in a suitable position, exerted a moderate inhibition (app.K i ca. 2–6 mmol/l). 3. Amongst 14 benzene sulfonates tested only 2 compounds (5-nitrobenzene-sulfonate and 2-hydroxy-5-nitrobenzenesulfonate) inhibited with aK i〈5 mmol/l. 4. Out of 10 naphthalene sulfonates tested 8 inhibited with aK i〈5; the highest inhibition was seen with the NH-containing 8-anilinonaphthalene-1-sulfonate (ANS), but no inhibition with 2 compounds containing an amino group. 5. From the polycyclic sulfonates pyrene-3-sulfonate and anthracene-1-sulfonate inhibited with aK i of approximately 2 mmol/l, while no inhibition was seen with anthracene-2-sulfonate. 6. Out of 4 amino-sulfonates tested benzene-1-amino-sulfonate and a similar benzyl-analog inhibited with aK i of 1 mmol/l and smaller; cyclohexyl-1-amino-sulfonate (cyclamate), however, inhibited only slightly (app.K i of 6 mmol/l). The data indicate that sulfate monoesters are well accepted by the contraluminal sulfate transport system. The affinity of sulfonate compounds to this system depends on neighbouring OH-groups −NH-groups, meta-positioned electronegative groups or a hydrophobic moiety in an appropriate position.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585338
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  • 13
    Electronic Resource
    Electronic Resource
    Contraluminal sulfate transport in the proximal tubule of the rat kidney (1985)
    Springer
    Pflügers Archiv 404 (1985), S. 311-318 
    Details
    ISSN: 1432-2013
    Keywords: Epithelial transport ; Contraluminal cell membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to evaluate the specificity for the contraluminal sulfate transport system the inhibitory potency of phenol- and sulfonphthaleins, of sulfamoyl-compounds (diuretics) as well as diphenylamine-2-carboxylates (Cl− channel blockers) on the35SO 4 2− influx from the interstitium into cortical tubular cells in situ has been determined. The following was found: 1) Phenolsulfonphthalein (phenol-red) inhibited with an app.K i-value of 1.7 mmol/l, while analogs which had additional Br-atoms in position 3 and/or 5, i.e. bromphenol-blue, bromcresol-purple and bromcresol-green, inhibited with an apparentK i of 0.1 and 0.5 mmol/l respectively. 2) Phenolphthalein and tetrabromphenolphthalein did not inhibit, while the disulfonate dyes bromsulfalein, fuchsin acid and indigocarmine inhibited with aK i between ≈1 and 3 mmol/l. The highest inhibitory potency in this class of compounds was seen with orange G (app.K i 0.07 mmol/l). The monosulfonate dyes tested, fluoresceinsulfonate and orange I inhibited moderately with an app.K i of ≈5 mmol/l. 3) The 3-sulfamoyl compounds inhibited to a varying degree, when they had a neighbouring −NH-group (furylmethylamino-group), i.e. in position 6 to the COOH or SO3H-group, or when they had a phenoxy-group in position 4. 4) 4-sulfamoylbenzoate and the related compounds probenecid, acetazolamide and hydrochlorothiazide inhibited with an app.K i between 4 and 7 mmol/l. 5) All diphenylamine-2-carboxylate analogs inhibited with an app.K i between 3 and 5 mmol/l, even when the −NH-group was replaced by an =O-group or the benzene ring was replaced by a pyrimidine ring, but not when it was replaced by a thiophen ring. In contrast, 4-phenylaminepyridine-3-sulfonate was ineffective, while diphenylamine-2-amino sulfonate exerted the highest inhibition of this group with an app.K i of 1.4 mmol/l. When, however, the aminosulfonate group was replaced by a methylsulfonamide, the inhibitory potency disappeared. The data can be explained by inhibitory patterns found in previous papers for disulfonates [29], sulfonates with a hydrophobic moiety [28] or neighbouring OH-group [28, 29], carboxylates with a neighbouring −NH- or OH-group in position 2- and an electron-attracting group in position 5 [30].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585341
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  • 14
    Electronic Resource
    Electronic Resource
    Specificity and sodium dependence of the active sugar tansport in the proximal convolution of the rat kidney (1974)
    Springer
    Pflügers Archiv 351 (1974), S. 35-48 
    Details
    ISSN: 1432-2013
    Keywords: Hexose Transport ; Sodium Cotransport ; Kidney Tubules ; Sugar Specificity ; Kidney Micropuncture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With the technique of stop flow microperfusion with simultaneous capillary perfusion, the zero net flux transtubular concentration difference (Δc) of labelled sugars was measured. The following sequence of Δc values, which are a measure for the active transtubular transport rate, were evaluated:d-glucose ≅β methyl-d-glycoside 〉α-methyl-d-glycoside 〉d-galactose 〉3-O-methyl-glucose 〉d-allose. When 10−4 M phlorrhizin was given in the luminal perfusate the Δc's dropped to zero (±8%). Δc-values in the same range i.e. indicating no active transport, were found for:l-glucose,d-mannose, 2-deoxy-d-glucose,d-fructose,d-glucosamine, 6-deoxy-d-galactose (=d-fucose),d-ribose and the reference polyalcohold-mannitol. Inhibition of thed-galactose δc was achieved by 15 mmol/l of the following sugars: α-methyl-d-glycoside ≅d-glucose ≅ 6-deoxy-d-glucose 〉3-O-methyl-d-glucose an no significant inhibition byd-xylose andd-mannose. Against Δc of α-methyl-d-glucose the following inhibitory potency was observed:d-glucose 〉6-deoxy-d-glucose 〉3-O-methyl-d-glucose ≅d-galactose 〉d-xylose and no inhibition byd-mannose. When the ambient sodium was replaced by choline, the Δc values of all actively transported sugars dropped toward zero. An analysis of the Na+ dependence of the α-methyl-d-glycoside transport revealed that the sodium dependence is of the affinity type i.e. that onlyK m increased with increasing Na+ concentration whileV max remained almost constant. From these data one can conclude: 1. The Crane specificity, i.e. that only the α-position of the OH-group on carbon atom 2 is essential, which was found for the intestinal hexose transport holds for the rat proximal kidney tubule, too. 2. The hexose transport system in the rat works only when Na+-ions are present. The sodium ions augment the affinity of the hexose transport system for the hexoses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603509
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  • 15
    Electronic Resource
    Electronic Resource
    Contraluminal para-aminohippurate transport in the proximal tubule of the rat kidney (1987)
    Springer
    Pflügers Archiv 409 (1987), S. 547-554 
    Details
    ISSN: 1432-2013
    Keywords: Dicarboxylate transport ; Sulfate transport ; Benzoyl compounds ; Phenoxy compounds ; Valproate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study the specificity of the contraluminal para-aminohippurate (PAH) transport system, the inhibitory potency of monocarboxylates on the3H-PAH influx from the interstitium into cortical tubular cells in situ has been determined. The following was found: if a homologous series of fatty acids with increasing chain length is tested, inhibition of contraluminal PAH influx is first seen with valerate (app.K i 1.4 mmol/l), increasing up to nonanoate (app.K i 0.06 mmol/l) and remaining in this range up to duodecanoate, the last compound of this series which is sufficiently water-soluble. Similarly, the inhibitory potency of aromatic monocarboxylates increases with increasing hydrophobicity. If the fatty acids are esterified, their inhibitory potency is lost. If they are transformed to the respective aldehydes their inhibitory potency is preserved at a reduced degree. Introduction of a hydrophobic methyl-, ethyl-, or propyl-group increases the inhibitory potency. A β-, but not an α-oxo-group augments the inhibitory potency of phenylpropionate analogs, an OH group diminishes it, and a NH2 group abolishes it. Among phenyl-fatty acids an increase in affinity is observed from phenyl- 〈 benzoylamine-〈 phenoxy- 〈 benzoyl-acetate and-propionate. All monocarboxylate compounds, so far tested, do not inhibit contraluminal sulfate and Na+/succinate influx. The data indicate that the PAH transporter interacts with monocarboxylates and also with aldehydes which have a hydrophobic moiety. An additional oxo-group facilitates the interaction. Thus, the benzoyl compounds show the highest affinity observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00584652
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  • 16
    Electronic Resource
    Electronic Resource
    Sodium dependence of the amino acid transport in the proximal convolution of the rat kidney (1974)
    Springer
    Pflügers Archiv 351 (1974), S. 49-60 
    Details
    ISSN: 1432-2013
    Keywords: Amino Acid Transport ; Sodium Cotransport ; Kidney Tubules ; Kidney Micropuncture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary With the technique of stop flow microperfusion with simultaneous capillary microperfusion the zero net flux transtubular concentration differences (Δc) of labelled amino acids which are equivalent to their active transport rates were measured. Alll-amino acids tested (phenylalanine, histidine, aminobicycloheptane-carboxylic acid, aminoisobutyric acid; lysine, ornithine, arginine; aspartic acid; proline and glycine) showed a considerable Δc, i.e. active transport rate. When, however, the ambient sodium was replaced by choline the Δc values dropped to zero. An analysis of the Na+ dependence of the ornithine transport revealed that the sodium-dependence is of the mixed type, i.e. thatK m decreased andV max increased with increasing Na+ concentration to the same extent. In contrast to other biological systems no mutual interaction between the Na+-dependentd-glucose andl-histidine transport could be observed. Incidental to these studies it was observed that the active transport rate ofd-histidine was in the range of 40% of that of thel-isomer while ford-phenylalanine it was only in the range of 10% of the active transport of thel-isomer. Furthermore it was found that thel-aspartic acid transport was already saturated at a luminall-aspartic acid concentration of 0.05 mmol/l while that ofl-phenylalanine was not saturated even at a luminal concentration of 9 mmol/l.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00603510
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  • 17
    Electronic Resource
    Electronic Resource
    Contraluminal sulfate transport in the proximal tubule of the rat kidney (1985)
    Springer
    Pflügers Archiv 404 (1985), S. 307-310 
    Details
    ISSN: 1432-2013
    Keywords: Epithelial transport ; Contraluminal cell membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study the specificity of the contraluminal sulfate transport system the inhibitory potency of salicylate analogs (5 mmol/l each) on the35SO 4 2− influx from the interstitium into cortical tubular cells in situ has been determined. The following was found: 2-hydroxybenzoate (salicylate), per se, did not inhibit contraluminal35SO 4 2− influx. The same holds when an additional NH2-group was introduced in position 4 or 5, or when an additional Cl-group was introduced in position 4. When an additional Cl- or NO2-group was introduced in position 5 a moderate inhibition was seen (app.K i≈4 mmol/l). However, introduction of 2 Cl- or 2 NO2-groups in position 3 and 5 creates compounds with strong inhibitory potency (app.K i≈0.5 mmol/l). 2-hydroxy-3,5-iodobenzoate inhibited too, but with a smaller inhibitory potency (app.K i≈2.3 mmol/l). 2-hydroxybenzoate analogs, which have a carboxy- or sulfo-group in position 5, exerted strong inhibition, those with a acetyl- or butyryl-group exerted moderate inhibition. 1-Naphthol-2-carboxylate did not inhibit, while 1-naphthol-4-sulfamoyl-2-carboxylate did. Amongst the dihydroxybenzoates, 2,3- and 2,5-dihydroxybenzoate did not inhibit contraluminal35SO 4 2− influx, while 2,4- and 2,6-dihydroxybenzoate did. The data indicate that a hydroxy-group in ortho-position and an electro-negative group in the meta-position to the carboxyl group and paraposition to the hydroxy-group are essential for interaction with the contraluminal sulfate transport system. The ability of 2,6-dihydroxybenzoate to inhibit might be explained by its ability to undergo mesomeric conformation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585340
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  • 18
    Electronic Resource
    Electronic Resource
    Contraluminal para-aminohippurate (PAH) transport in the proximal tubule of the rat kidney (1988)
    Springer
    Pflügers Archiv 413 (1988), S. 134-146 
    Details
    ISSN: 1432-2013
    Keywords: Organic anion transport ; Sulfate transport ; Dicarboxylate transport ; Phenolate transport ; Salicylate transport ; Cinnamate transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to study the specificities of the contraluminal anion transport systems, the inhibitory potency of substituted benzene analogs on influx of [3H]PAH, [14C]succinate, and [35S]sulfate from the interstitium into cortical tubular cells has been determined in situ: (1) Contraluminal [3H]PAH influx is moderately inhibited by benzene-carboxylate and benzene-sulfonate, and strongly by benzene-dicarboxylates,-disulfonates and carboxy-benzene-sulfonates, if the substituents are located at positions 1 and 3 or 1 and 4. The affinity of the PAH transporter to polysubstituted benzoates increases with increasing hydrophobicity, decreasing electron density at the carboxyl group and decreasing pKa. Similar dependencies are observed for phenols. Benzaldehydes which do not carry an ionic negative charge are accepted by the PAH-transporter, if they possess a second partially charged aldehyde or NO2-group. (2) Contraluminal [14C]succinate influx is inhibited by benzene 1,3- or 1,4-dicarboxylates,-disulfonates and 1,3-or 1,4-carboxybenzene-sulfonates. Monosubstituted benzoates do not interact with the dicarboxylate transporter, but NO2-polysubstituted benzoates do. Phenol itself and 2-substituted phenol interact weakly possibly due to oligomer formation. (3) The contraluminal sulfate transporter interacts only with compounds which show a negative group accumulation such as 3,5-dinitro- or 3,5-dichloro-substituted salicylates. The data are consistent with three separate anion transport systems in the contraluminal membrane: The PAH transporter interacts with hydrophobic molecules carrying one or two negative charges (−COO−, −SO 3 − ) or two or more than two partial negative charges (−OH, −CHO, −SO2NH2, −NO2). The dicarboxylate transporter requires two electronegative ionic charges (−COO−, −SO 3 − ) at 5–9 Å distance or one ionic and several partial charges (−Cl, −NO2) at a favourable distance. The sulfate transporter interacts with molecules which have neighbouring electronegative charge accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582523
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