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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Localization of sodium in forg skin by electron microprobe analysis (1974)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 281 (1974), S. 271-280 
    Details
    ISSN: 1432-1912
    Keywords: Sodium Transport ; Frog Skin ; Electron Probe Micro Analysis ; Ouabain ; Amiloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The intracellular Na and K concentrations in the different layers of the frog skin were measured using the electron microprobe. The experiments were carried out under control conditions and after inhibition of the transcellular Na transport by ouabain, amiloride and reduction of the Na concentration in the epithelial bathing solution to zero. After measuring the short-circuit current in an Ussing type chamber the skin was shockfrozen at-140°C, cryosectioned (2–3 μm) at-70°C and freezedried. For quantitation sections from albumin solution with known electrolyte concentrations were prepared in the same manner as the skin. After ouabain the Na concentrations of all epithelial cells increased, whereas the K concentration decreased to the same extent. The action of amiloride and the incubation of the epithelial side with Na-free Ringer solution caused a decrease of intracellular Na concentration only in the outermost functional cell layer of the frog skin. Therefore it is concluded that this cell layer is responsible for transcellular Na transport. In most experiments the cornified layer showed the same electrolyte concentrations as the epithelial bathing solution, which were not altered by amiloride or ouabain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500596
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