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  • 1
    Electronic Resource
    Electronic Resource
    The distribution of potassium, sodium and chloride across the apical membrane of renal tubular cells: effect of acute metabolic alkalosis (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 259-267 
    Details
    ISSN: 1432-2013
    Keywords: Acute metabolic alkalosis ; Distal sodium delivery ; Intracellular electrolyte concentrations ; Individual distal tubule cells ; Transmembranal electrolyte concentration gradients ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies were undertaken to define the effect of acute metabolic alkalosis (hypertonic sodium bicarbonate i.v.) on the chemical gradients for potassium, sodium and chloride across the apical membrane of individual renal tubule cells. Electron microprobe analysis was used on freeze-dried cryosections of the rat renal cortex to measure electrolyte concentrations in proximal tubule cells and in the various cell types of the superficial distal tubule. Analyses were also performed in fluid samples obtained by micropuncture from proximal and early and late distal collection sites. Compared with the appropriate controls (hypertonic sodium chloride i.v.), administration of sodium bicarbonate resulted only in small and mostly insignificant increases in cell potassium concentrations and induced only minor alterations in the cell/tubule fluid potassium concentration gradient for all cell types analysed. This observation suggests that under this condition factors other than an increase in cell potassium concentration are important in modulating potassium transfer across the apical membrane of potassium secreting cells. Nevertheless, since in alkalosis phosphorus and cell dry weight were decreased, and hence cell volume increased, in all but the intercalated cells, actually the potassium content of most tubular cells was higher under this condition. In comparison with animals infused with isotonic saline at low rates (hydropenic controls), infusion of either hypertonic sodium chloride or sodium bicarbonate led to a sharp increase in distal tubule fluid sodium concentrations and in the sodium concentrations of distal convoluted tubule, connecting tubule and principal cells, indicating that under both conditions the primary event causing enhanced transepithelial sodium absorption is stimulation of the sodium entry step. The ensuing rise in cell sodium concentration shold lead secondarily to stimulation of active basolateral sodium extrusion. Intercalated cell sodium concentration was higher only in alkalosis which supports the notion that this cell type is not involved in transepithelial sodium transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585112
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    Effect of amiloride on electrolyte concentrations and rubidium uptake in principal and mitochondria-rich cells of frog skin (1990)
    Springer
    Pflügers Archiv 416 (1990), S. 335-338 
    Details
    ISSN: 1432-2013
    Keywords: Rubidium ; Amiloride ; Na/K-ATPase ; Electrolyte concentrations ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The role of mitochondria-rich cells (MR cells) in transepithelial Na transport was investigated by determining electrolyte concentrations and Rb uptake in individual cells of frog skin epithelium using electron microprobe analysis. Measurements were performed under control conditions and after blocking the transepithelial Na transport with amiloride. Under control conditions, Na and Cl concentrations of MR cells scattered much more than those of principal cells and ranged from a few up to more than 30 mmol/kg wet weight. Rb uptake from the basal side into individual MR cells also showed a large variation and was, on the average, much less pronounced than into the principal cells. In principal cells, amiloride reduced the Na concentration and Rb accumulation. In contrast, no effect was observed upon electrolyte concentration and Rb uptake of MR cells. Rb uptake was correlated to the Na concentration of MR cells both under control conditions and after amiloride. It is concluded that, in contrast to the principal cells, MR cells are not involved in amiloride-sensitive transepithelial Na transport and that their Na/K-pump activity is very low.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392070
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of potassium adaptation on the distribution of potassium, sodium and chloride across the apical membrane of renal tubular cells (1987)
    Springer
    Pflügers Archiv 409 (1987), S. 477-485 
    Details
    ISSN: 1432-2013
    Keywords: K adaptation ; Cell electrolyte concentrations ; Distal tubular cell types ; Micropuncture ; Chemical driving force ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To assess the effect of K adaptation on the electrolyte concentrations of renal tubular cells and on the concentration gradients across the luminal membrane, electron microprobe analysis was employed on freeze-dried cryosections of the renal cortex and on freeze-dried samples of tubular fluid in control and high-K rats. The measurements were performed in individual cells of the proximal and superficial distal tubule and on samples of tubular fluid obtained by free flow micropuncture from proximal and early and late distal collection sites. The ingestion of a potassium-rich diet for at least 10 days together with an acute potassium load of 0.4 mmol/kg/h led to a small increase in potassium concentration of about 7 mmol/kg wet weight (w.w.) in all cell types analysed. In distal convoluted tubule, connecting tubule and principal cells sodium concentration was markedly decreased by 4, 4, and 6 mmol/kg w.w., respectively, while no significant changes in sodium concentration were found in proximal tubule and intercalated cells. No consistent changes in cell chloride could be observed under K adaptation. Analysis of the tubular fluid samples showed that the K concentration gradient across the apical cell membrane of all distal tubular cell types investigated was diminished in the high-K rats. The concentration gradient for sodium entry, however, was clearly enhanced in the distal convoluted tubule, connecting tubule and principal cells. These data suggest that an increment in cell potassium concentration is not a major functional determinant for the increased distal K secretion observed in high-K rats and that the enhanced distal sodium absorption under this condition may be due to a stimulation of the Na exit step across the basolateral cell membrane in excess of the luminal entry step in most distal tubular cell types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583804
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  • 5
    Electronic Resource
    Electronic Resource
    Cl transport across the basolateral membrane in frog skin epithelium (1985)
    Springer
    Pflügers Archiv 405 (1985), S. S8 
    Details
    ISSN: 1432-2013
    Keywords: Electron microprobe analysis ; Cellular Cl concentration ; Co-transport ; Frog skin epithelium ; Furosemide ; Bumetanide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cellular Cl concentrations were determined by electron microprobe analysis to obtain further insight into the Cl transport across the basolateral membrane of the frog skin epithelium. Cl-free media on the serosal side led in all epithelial layers within 1 h to a decrease in cellular Cl concentration from about 40 to 15 mmol/kg wet wt, whereas the application of Cl-free solutions or amiloride to the apical side had no effect. Na-free media, furosemide or bumetanide on the serosal side had little effect on cellular Cl but abolished the Cl-reuptake into Cl-depleted cells. It is concluded that cellular Cl concentration is maintained above electrochemical equilibrium by a co-transport system, which is relatively silent under control conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581772
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  • 6
    Electronic Resource
    Electronic Resource
    Osmoregulation of renal papillary cells (1985)
    Springer
    Pflügers Archiv 405 (1985), S. S28 
    Details
    ISSN: 1432-2013
    Keywords: Cellular osmoregulation ; Rat renal papilla ; Antidiuresis ; Diuresis ; Electron microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Element concentrations were determined in various extra- and intracellular compartments of the rat renal papilla in antidiuresis and after furosemide-induced diuresis using electron microprobe analysis to elucidate further how the cells adapt osmotically to different osmolatities. In antidiuresis and diuresis the sum of intracellular cations (sodium and potassium), accompanying anions and urea was insufficient in both cases to provide cell osmolatities similar to those in extracellular compartments. This finding provides further evidence that the papillary cells achieve osmoadaptation to widely differing extracellular electrolyte concentrations mainly by varying the cellular concentrations of osmotically-active substances other than urea and electrolytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581776
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  • 7
    Electronic Resource
    Electronic Resource
    Na transport compartment in rabbit urinary bladder (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 681-687 
    Details
    ISSN: 1432-2013
    Keywords: Rabbit urinary bladder ; Electron microprobe analysis ; Na transport compartment ; Ouabain ; Nystatin ; Rb-uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Electron microprobe analysis was used to determine cellular electrolyte concentrations in rabbit urinary bladder. Under control conditions the mean cellular electrolyte concentrations were for Na 11.6±2.0, for K 124.1±15.3, and for Cl 26.0±5.1 mmol/kg wet weight. The dry weight content was 19.0±2.0 g/100 g. Inhibition of the Na/K-pump with ouabain resulted in drastic changes of the cellular element concentrations. Similar changes also occurred when in addition to ouabain the apical side was kept Na-free. In all epithelial layers the Na and Cl concentrations increased by 90 and 30 mmol/kg wet weight, whereas the K concentration and the dry weight content decreased by 90 mmol/kg wet weight and 6 g/100 g wet weight, respectively. With Na-free choline-Ringer's solution on the basal side ouabain led to a decrease in the K concentration by about 60 mmol/kg wet weight while the Na and Cl concentrations remained unchanged. These data indicate that the basolateral membrane is permeable to Na, choline, Cl, and K. Nystatin produced drastic changes in the cellular electrolyte concentrations when Na- or Rb-sulfate Ringer's solutions were present on the apical side. With Na-sulfate Ringer's solution the Na concentration increased by about 25, the Cl concentration by 30 mmol/kg wet weight and the dry weight content decreased by 4.5 g/100 g, respectively. With Rb-Ringer's solution about 20 mmol/kg wet weight of the cellular K was exchanged against Rb. The concentration changes were identical in all epithelial layers supporting the idea that the rabbit urinary bladder represents a functional syncytium with regard to the transepithelial Na transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580866
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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Localization of transport compartments in turtle urinary bladder (1989)
    Springer
    Pflügers Archiv 414 (1989), S. 208-215 
    Details
    ISSN: 1432-2013
    Keywords: Electron microprobe analysis ; Cellular electrolyte concentrations ; Na transport ; Ouabain-sensitive and-insensitive cells ; Amiloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To characterize different transport compartments in the urinary bladder epithelium of postabsorptive turtles, the electrolyte composition of individual cells was determined using electron microprobe analysis. After blocking the transepithelial Na transport, the short-circuit current decreased from positive to negative values (from 26.5±17.7 to −3.9±2.9 after ouabain and from 25.4±17.2 to −8.0±5.1 μA/cm2 after amiloride). Whereas under control conditions the Na and K concentrations were similar in all cell types and the same was true for Cl in most of the cells, some cells exhibited very low Cl concentrations. The epithelial cells were subdivided according to their electrolyte composition into ouabain-sensitive and ouabain-insensitive ones. In the ouabain-sensitive cells, which made up the majority of epithelial cells and showed a relatively high Cl concentration (about 36 mmol/kg wet weight), the Na concentration increased after ouabain by about 90 mmol/kg wet weight and the K concentration decreased by a similar amount. Since these alterations could largely be prevented when amiloride was applied before ouabain, it is suggested that the granular and basal cells form a syncytial Na transport compartment similar to that in other multilayered epithelia. The ouabain-insensitive cells, in which almost no alteration in Na and K concentrations was observed after ouabain, were subdivided into a Cl-rich (34.6±7.6 mmol/kg wet weight) and a Cl-poor (12.0±5.6 mmol/kg wet weight) population. Since in these cells no large mucin granules were detectable, they are regarded as carbonic anhydrase-rich cells involved in H and HCO3 transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580965
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