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  • 1
    Electronic Resource
    Electronic Resource
    Effect of ouabain on electrolyte concentrations in principal and intercalated cells of the isolated perfused cortical collecting duct (1989)
    Springer
    Pflügers Archiv 413 (1989), S. 651-655 
    Details
    ISSN: 1432-2013
    Keywords: Cortical collecting duct ; Isolated perfused tubules ; Principal cells ; Intercalated cells ; Cell electrolyte concentrations ; Ouabain ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sodium, phosphorus, chloride and potassium concentrations were measured by a new method in individual principal and intercalated cells in the cortical collecting duct in vitro. Electron microprobe analysis was applied to freezedried cryosections of the isolated perfused rabbit cortical collecting duct. Cell analyses were performed under control conditions and after addition of ouabain to the bath. Under control conditions similar sodium, potassium, chloride, and phosphorus concentration (means±SEM) were observed in principal (10.0±0.6, 126.5±2.7, 24.6±1.0, and 121.5±3.5 mmol/kg wet weight, respectively) and intercalated cells (9.0±0.9, 127.1±4.2, 27.4±1.8, and 118.7±4.9 mmol/kg wet weight, respectively). In principal cells ouabain (10 min) caused an increase in sodium and chloride concentrations by 104 and 13 mmol/kg wet weight, and a decrease in potassium and phosphorus concentrations by 106 and 32 mmol/kg wet weight. These changes in cell element concentrations can be ascribed to an exchange of intracellular potassium against extracellular sodium and to cell swelling due to influx of extracellular fluid. The effects of ouabain on intercalated cells were far less pronounced than on principal cells. This different susceptibility to ouabain of principal and intercalated cells can be ascribed to differences in active and passive transmembrane ion transport pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581816
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  • 2
    Electronic Resource
    Electronic Resource
    Cellular osmoregulation in the renal papilla (1988)
    Springer
    Journal of molecular medicine 66 (1988), S. 843-848 
    Details
    ISSN: 1432-1440
    Keywords: Renal papillary cells ; Cell electrolytes ; Osmoadaptation ; Organic osmolytes ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The cells of the renal papilla are subject to extreme variations in extracellular tonicity. To obtain more insight into the mechanisms whereby these cells adapt osmotically to these unique environmental conditions, elements were measured in individual cells of the rat renal papilla in antidiuresis and after prolonged furosemide administration. In antidiuresis cell sodium, chloride and potassium concentrations did not differ fundamentally from those observed in tubule cells exposed to isotonic surroundings such as in proximal tubule cells. The marked fall in extracellular electrolyte concentrations induced by furosemide was paralleled by a far less pronounced decline in intracellular sodium, chloride and potassium concentrations. These data indicate that papillary cells achieve osmoadaptation to widely differing extracellular tonicities mainly by varying the intracellular concentrations of osmotically active substances other than inorganic electrolytes. Since high concentrations of organic osmolytes (sorbitol, inositol, glycerophosphorylcholine and other trimethylamines) have been detected in the papilla and since the tissue contents of these compounds have been shown to vary in parallel with urine osmolality, it may be concluded that metabolically inert, organic osmolytes play a dominant role in the osmoregulation of renal papillary cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01728945
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of increased distal sodium delivery on organic osmolytes and cell electrolytes in the renal outer medulla (1992)
    Springer
    Pflügers Archiv 422 (1992), S. 233-238 
    Details
    ISSN: 1432-2013
    Keywords: Renal outer medulla ; Cell electrolytes ; Sodium loading ; Cell osmoregulation ; Organic osmolytes ; Glycerophosphorylcholine ; Betaine ; Inositol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sodium absorption in distal tubule segments was stimulated by increasing the distal delivery via infusion of hypertonic saline. In these animals, and in control rats, electrolyte concentrations in thick ascending limb cells, light and dark cells of the collecting duct in the outer and inner stripe of the outer medulla and in cells of the proximal straight tubule (outer stripe only) were studied. The measurements were performed by electron microprobe analysis of freeze-dried cryosections of the outer medulla. In addition, organic osmolytes (glycerophosphorylcholine, betaine and myo-inositol) were measured by high performance liquid chromatography in cortex and outer medulla. Augmented delivery of sodium chloride to the distal tubule was associated with increased sodium concentrations of thick ascending limb cells both in the outer and inner stripe and of medullary collecting duct light and dark cells in the outer stripe. While the sum of organic osmolyte concentrations was 28% higher in the outer medulla of the salt-loaded animals compared with controls, this value was unchanged in the renal cortex. These findings indicate that the primary event underlying stimulation of sodium absorption along the thick ascending limb during increased distal sodium delivery is enhanced entry of sodium across the apical cell membrane. This would be expected to lead to higher cell sodium concentrations and stimulation of basolateral active Na-K-exchange. The enhanced transport activity of outer medullary tubules may be associated with increased interstitial tonicities and intracellular retention of organic osmolytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376207
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  • 4
    Electronic Resource
    Electronic Resource
    Transcellular sodium transport and basolateral rubidium uptake in the isolated perfused cortical collecting duct (1993)
    Springer
    Pflügers Archiv 424 (1993), S. 250-254 
    Details
    ISSN: 1432-2013
    Keywords: Cortical collecting duct ; Cell Na+ concentration ; Cell Rb+ uptake ; Na+/K+-ATPase activity ; Principal cell ; Intercalated cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The relation between transcellular Na+ absorption, intracellular Na+ concentration and Na+/K+-ATPase activity (the last estimated by the rubidium uptake across the basolateral cell membrane) was examined in the different cell types of the rabbit cortical collecting duct (CCD). Experiments were performed on isolated perfused CCD in which Na+ absorption was varied by perfusing the tubule with solutions containing different Na+ concentrations (nominally Na+-free, 30 mM and 144 mM). Experiments were terminated by shock-freezing the tubules during perfusion. Precisely 30 s before shock-freezing, the K+ in the bathing solution was exchanged for Rb+. Intracellular element concentrations, including Rb+, were determined in freeze-dried cryosections of the tubules using energy-dispersive X-ray analysis. Increasing Na+ concentration in the perfusion solution caused significant rises in intracellular Na+ concentration and Rb+ uptake of principal cells. Principal cell Na+ and Rb+ concentrations were 7.8±0.9 and 7.0±0.8 mmol/kg wet weight respectively, when the perfusion solution was Na+-free, 10.1±0.7 and 11.6±0.6 mmol/kg wet weight with 30 mM Na+ in the perfusion solution, and 14.5±1.5 and 14.9 ±0.9 mmol/kg wet weight with 144 mM Na+ in the perfusion solution. In contrast, a comparable relationship between lumen Na+ concentration, intracellular Na+ concentration and basolateral Rb+ uptake was not seen in intercalated cells. These results support the notion that principal, but not intercalated, cells are involved in transepithelial Na+ absorption. In addition, the data demonstrate that apical Na+ entry and basolateral Na+/K+-AT-Pase activity are closely coupled in principal cells of the rabbit CCD. A rise in lumen Na+ concentration leads to increased Na+ entry and augmented intracellular Na+ concentration, which then secondarily stimulates active basolateral Na+/K+(Rb+) exchange.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384350
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  • 5
    Electronic Resource
    Electronic Resource
    Pretreatment with hypertonic NaCl protects MDCK cells against high urea concentrations (1998)
    Springer
    Pflügers Archiv 435 (1998), S. 407-414 
    Details
    ISSN: 1432-2013
    Keywords: Key words MDCK cells ; Hypertonic stress ; NaCl ; Urea ; Organic osmolytes ; Heat shock proteins ; Cell viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In antidiuresis, the cells of the renal medulla are exposed to high extracellular concentrations of NaCl and urea. Since urea equilibrates with the intracellular compartment and is known to perturb intracellular macromolecules, high urea concentrations may well disturb the structure and function of cell proteins. Two types of organic substances are believed to counteract the adverse effects of high intracellular urea concentrations: specific organic osmolytes of the trimethylamine family [betaine and glycerophosphorylcholine (GPC)], which accumulate in renal medullary cells during prolonged periods of antidiuresis and cytoprotective heat shock proteins (HSPs), the tissue content of two of which (HSPs 27 and 72) is much higher in the inner medulla than in the iso-osmotic renal cortex. To evaluate the contribution of trimethylamines and HSPs to cytoprotection in the presence of high urea concentrations, the effect of HSP induction and osmolyte accumulation prior to exposure to high urea concentrations was examined in Madin-Darby canine kidney (MDCK) cells. Accumulation of organic osmolytes and synthesis of HSP27 and HSP72 was initiated by hypertonic stress (increasing the osmolality of the medium from 290 to 600 mosmol/kg H2O by NaCl addition). Control, non-conditioned cells remained in the isotonic medium for the same period. Upon subsequent exposure to an additional 600 mM urea in the medium for 24 h, 90% of the osmotically conditioned cells but only 15% of non-conditioned cells survived. The HSP72 and trimethylamine contents of the NaCl-conditioned MDCK cells, but not HSP27 content, correlated positively with cell survival. To separate the effects of organic osmolytes and HSP72, chronically NaCl-adapted MDCK cells were returned to isotonic medium for 1 or 2 days, so depleting them of trimethylamine osmolytes. HSP72, with its longer half life, remained elevated. Subsequent exposure of these cells to 600 mM urea in the medium resulted in about 80% survival. These results suggest that in MDCK cells and probably in the renal medulla, HSP72 and perhaps additional protective factors contribute substantially to the resistance against high urea concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240050531
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  • 6
    Electronic Resource
    Electronic Resource
    Sodium entry routes in principal and intercalated cells of the isolated perfused cortical collecting duct (1990)
    Springer
    Pflügers Archiv 416 (1990), S. 88-93 
    Details
    ISSN: 1432-2013
    Keywords: Cortical collecting duct ; Principal cells ; Intercalated cells ; Cell electrolyte concentrations ; Ouabain ; Amiloride ; Na-H exchange ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Transmembrane sodium transport pathways were studied in principal and intercalated cells of the isolated perfused rabbit cortical collecting duct. Intracellular electrolyte concentrations in individual collecting duct cells were measured by electron microprobe analysis during blockage of basolateral Na-K-ATPase by ouabain and simultaneous inhibition of sodium entry across the apical and/or basolateral cell membrane. In principal cells the ouabain-induced rise in cell sodium concentration could only partially be blocked by amiloride (10−4mol/l) in the perfusion fluid. Amiloride (10−3mol/l) added to the bathing solution produced a further, significant reduction of sodium influx. In principal cells the ouabain-induced increase in sodium concentration was completely prevented by amiloride in the perfusion solution in combination with omission of sodium from the peritubular bathing solution. In intercalated cells ouabain caused a less pronounced increase in sodium concentration than in principal cells. Neither amiloride in the perfusate, nor amiloride in both bathing and perfusion solution, significantly reduced the ouabain-induced rise in intercalated cell sodium concentration. These results indicate that in principal cells amiloride-sensitive sodium channels constitute the predominant pathway for sodium entry across the apical cell membrane. In addition, substantial amounts of sodium enter principal cells across the basolateral cell membrane, probably via Na-H exchange. Finally, the data suggest that in intercalated cells sodium channels and the Na-H exchange are sparse or even absent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00370227
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