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  • 1
    Electronic Resource
    Electronic Resource
    Transport Compartments in the Turtle Urinary Bladder An Electron Microprobe Analysis (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 574 (1989), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1989.tb25186.x
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  • 2
    Electronic Resource
    Electronic Resource
    Electron-Probe X Ray Microanalysis of Transepithelial Ion Transport (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 483 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb34528.x
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  • 3
    Electronic Resource
    Electronic Resource
    Intracellular ion concentrations in the frog cornea epithelium during stimulation and inhibition of Cl secretion (1987)
    Springer
    The journal of membrane biology 95 (1987), S. 229-240 
    Details
    ISSN: 1432-1424
    Keywords: intracellular electrolytes ; epithelial transport ; Cl secretion ; cell volume regulation ; frog cornea ; isoproterenol ; ionophore A23187 ; ouabain ; bumetanide ; furosemide ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The intracellular electrolyte concentrations in the isolated cornea of the American bullfrog were determined in thin freeze-dried cryosections using energy-dispersive X-ray microanalysis. Stimulation of Cl secretion by isoproterenol resulted in a significant increase in the intracellular Na concentration but did not change the intracellular Cl concentration. Similar results were obtained when Cl secretion was stimulated by the Ca ionophore A23187. Inhibition of Cl secretion by ouabain produced a large increase in the intracellular Na concentration and an equivalent fall in the K concentration. Again, no increase or decrease in the intracellular Cl concentration was detectable. Clamping of the transepithelial potential to ±50 mV resulted in parallel changes in the transepithelial current and intracellular Na concentration, but, with the exception of the outermost cell layer, in no changes of the Cl concentration. Only when Cl secretion was inhibited by bumetanide or furosemide, together with a decrease in the Na concentration, was a large fall in the Cl concentration observed. Application of loop diuretics also produced significant increases in the P concentration and dry weight, consistent with some shrinkage of the epithelial cells. The results suggest the existence of a potent regulatory mechanism which maintains a constant intracellular Cl concentration and, thereby, a constant epithelial cell volume. Through the operation of this system any variation in the apical Cl efflux is compensated for by an equal change in the rate of Cl uptake across the basolateral membrane. Cl uptake is sensitive to loop diuretics, directly coupled to an uptake of Na, and dependent on the Na and K concentration gradients across the basolateral membrane. Isoproterenol and A23187 seem to increase the Cl permeability of the apical membrane and thus stimulate Cl efflux. Ouabain inhibits Cl secretion by abolishing the driving Na concentration gradient for Cl uptake across the basolateral membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869485
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  • 4
    Electronic Resource
    Electronic Resource
    Intracellular solute gradients during osmotic water flow: An electron-microprobe analysis (1987)
    Springer
    The journal of membrane biology 96 (1987), S. 85-94 
    Details
    ISSN: 1432-1424
    Keywords: ADH ; osmotic water flow ; transepithelial Na transport ; toad urinary bladder epithelium ; X-ray microanalysis ; intracellular ion concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary In an attempt to quantify possible intracellular water activity gradients during ADH-induced osmotic water flow, we employed energy dispersive X-ray microanalysis to thin, freezedried cryosections obtained from fresh, shock-frozen tissue of the toad urinary bladder. The sum of all detectable small ions (Na + K + Cl) in the cellular water space was taken as an index of the intracellular osmolarity. Presuming that all ions are osmotically active, they comprise about 90% of the cellular solutes. When the cells were exposed to dilute serosal medium, the reduction in the sum of the ions agreed well with the expected reduction in osmolarity. After inducing water flow by addition of ADH and dilution of the mucosal medium, all epithelial cells showed a fall in osmolarity. The change was more pronounced in granular cells than in basal or mitochondria-rich cells, consistent with the notion that granular cells represent the main transport pathway. Most significantly, intracellular osmolarity gradients, largely caused by an uneven distribution of K and Na, were detectable in granular cells. The gradients were not observed after ADH or mucosal dilution alone, or when the direction of transepithelial water flow was reversed. We conclude from these results that there is a significant cytoplasmic resistance to water flow which may lead to intracellular gradients of water activity. Concentration gradients of diffusible cations can be explained by a flow-induced Donnan-type distribution of fixed negative charges. With regard to transepithelial Na transport, the data suggest that ADH stimulates transport by increasing the Na permeability of the apical membranes of granular cells specifically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01869337
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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Determination of electrolytes in small biological fluid samples using energy dispersive X-ray microanalysis (1977)
    Springer
    Pflügers Archiv 369 (1977), S. 95-98 
    Details
    ISSN: 1432-2013
    Keywords: X-ray microanalysis ; Electrolytes ; Picoliter fluid samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A technique is reported for the application of the energy dispersive X-ray microanalysis for the simultaneous determination of electrolytes in picoliter samples of biological fluids. The preparation is characterized by the use of thin films as a specimen support. Using this arrangement, the X-rays generated in the support are kept to a minimum. At an acceleration voltage of 25 kV the specimen preparation can be regarded as ‘thin’, i.e. the intensity of an emitted characteristic radiation is almost uninfluenced by the gross elemental composition, and, therefore, is only dependent upon the content of elements. Quantification was achieved by comparing the intensities of the characteristic radiations with that of a standard. Electrolyte concentrations of 1 mM can be detected with an accuracy of 0.1 mM SD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00580817
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  • 7
    Electronic Resource
    Electronic Resource
    The osmotic behaviour of toad skin epithelium (Bufo viridis) (1980)
    Springer
    Pflügers Archiv 385 (1980), S. 1-10 
    Details
    ISSN: 1432-2013
    Keywords: Electron microprobe analysis ; Toad skin epithelium ; Intracellular electrolyte concentrations ; Osmotic behaviour ; Salinity adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of saline adaptation on the intracellular Na, K, Cl, P concentrations and dry weight content of the toad skin epithelium (Bufo viridis) was studied using the technique of electron microprobe analysis. The measurements were performed on isolated abdominal skins either directly after dissection or after additional incubation in Ussing-type chambers. Adaptations of the toads to increasing NaCl concentrations for 7 days resulted in increased blood plasma osmolarity and a parallel increase in the cellular electrolyte, P and dry weight concentrations of the epithelium, the K increase representing the most significant fraction of the intracellular osmolarity increase. No evidence was obtained to show that the nucleus and cytoplasm reacted differently from each other and all living epithelial cell types basically showed the same response. Incubation of the isolated skins under control conditions showed a drastic inhibition of the transepithelial Na transport after adaptation to high salinities. In spite of the large variations in the transport rate almost identical intracellular electrolyte concentrations were observed. In tap water adapted toads the average cellular concentrations were 8.8 mmole/kg wet weight for Na, 109.6 for K, 41.5 for Cl, and 135.3 for P, respectively. Incubation of the skin with Ringer's solution of different osmolarities demonstrated that the epithelial cells are in osmotic equilibrium with the inner bathing solution. The results are consistent with the view that the osmotic adaptation is mainly accomplished by the movement of water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00583908
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  • 8
    Electronic Resource
    Electronic Resource
    Na transport stimulation by novobiocin: intracellular ion concentrations and membrane potential (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 505-513 
    Details
    ISSN: 1432-2013
    Keywords: Novobiocin ; Amiloride ; Transepithelial Na transport ; Intracellular ion concentrations ; X-ray microanalysis ; Intracellular microelectrodes ; Na permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Microelectrodes and electron microprobe analysis were employed to study the effect of novobiocin on membrane potential and intracellular electrolyte concentrations in the frog skin epithelium. In both species investigated (Rana esculenta andRana temporaria), novobiocin (1 mM, outer bath) caused a stimulation of transepithelial Na transport, a depolarization of apical membrane potential, a fall in the apical fractional resistance, and an increase in the intracellular Na concentration. The rise in the Na concentration was accompanied by an equivalent fall in the K concentration. All effects of novobiocin were fully reversible by subsequent application of amiloride. The depolarization as well as the Na increase suggests that the natriferic effect of novobiocin is due to a stimulation of the apical Na influx. Combining both measurements it was possible to calculate the effect of novobiocin on the Na permeability of the apical membrane directly. InRana esculenta novobiocin increased the permeability from 4.5 to 23.2 nm/s. InRana temporaria the increase was significantly smaller, from 8.7 to 16.9 nm/s. The transport rate as measured by the short-circuit current showed a non-linear dependence on the apical Na permeability. In the range of transport rates normally encountered, however, the current was a linear function of the Na permeability consistent with the view that the apical membrane is rate-limiting in transepithelial Na transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582371
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  • 9
    Electronic Resource
    Electronic Resource
    X-ray microanalysis of receptor lymph in a cuticular arthropod sensillum (1976)
    Springer
    Journal of comparative physiology 110 (1976), S. 89-95 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In an effort to learn about its possible significance for transduction processes the receptor lymph of the spider slit sensillum was collected from in vivo preparations. Its elemental contents were then analyzed by X-ray microanalysis with an emphasis on Na and K, i.e. the cations most widely involved in excitation processes. We found high concentrations of Na and Cl, but almost no K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00656783
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  • 10
    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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