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  • Amphibian skin  (3)
  • Na Transport  (2)
  • Transport Pool  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Opposite effects of indacrinone (MK-196) on sodium and chloride conductance of amphibian skin (1985)
    Springer
    Pflügers Archiv 403 (1985), S. 337-343 
    Details
    ISSN: 1432-2013
    Keywords: Shunt pathway ; Diuretics ; Sodium transport chloride conductance ; Amphibian skin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Indacrinone, a drug chemically related to ethacrynic acid, usually stimulated reversibly short circuit current and sodium influx when applied to the epithelial surface of amphibian skin. Concomitantly, transepithelial conductance,g t, decreased, provided chloride was the main anion in the incubation fluid. Electrophysiological analysis including microelectrode impalement indicated that the drug increased the sodium-conductance at the apical border of the impaled (most likely granular) cells. The decrease ing t thus points at shunt conductance being reduced with indacrinone, sometimes drastically. Decrease of transepithelial chloride flux with the drug as well as lack of effect of the drug ong t in the absence of chloride on the epithelial side demonstrate the influence of indacrinone on a chloride specific pathway. Whether this is along a paracellular route or through a cellular compartment not coupled to granular cells (mitochondria-rich cells?) cannot be decided on the basis of the present data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00589243
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Wash out characteristics of tracer Na from the transport pool of frog skin (1978)
    Springer
    Pflügers Archiv 374 (1978), S. 235-241 
    Details
    ISSN: 1432-2013
    Keywords: Frog skin ; Na Transport ; Wash out kinetics ; Amiloride ; Ouabain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Wash out analysis of tracer Na from frog skins after labelling from the epithelial or corial side was performed under control conditions and after transport inhibition by amiloride or ouabain. Wash out from the transport pool, i. e. after labelling from the epithelial side, into the corial bathing solution could be resolved into two individual components under all conditions. The fast one with half times of wash out of about 1.8 min correlates with the rate of transepithelial Na transport. It cannot unequivocally be associated with intra- or extracellular tissue spaces. The slow component with half times of about 18 min is essentially independent of the transport rate. The amount of Na washed out as this component increased considerably after transport inhibition with ouabain, suggesting intracellular location of at least a fraction of the transport pool, which appears to be made up by the entire epithelial cell layers. Wash out of tracer Na from the transport pool to the epithelial side is small compared to wash out to the corial side. Tracer wash out characteristics after labelling from the corial side were similar for wash out to the epithelial and the corial side. This suggests that considerable paracellular fluxes contribute to the Na flux from the corial to the epithelial side. The total intracellular Na present in the epithelium after ouabain can be labelled from the corial side. Carrier mediated Na−Na exchange across the basolateral membranes is proposed to account for this.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585600
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Procaine effects on sodium and chloride transport in frog skin (1988)
    Springer
    Pflügers Archiv 411 (1988), S. 386-393 
    Details
    ISSN: 1432-2013
    Keywords: Chloride conductance ; Sodium permeability ; Mitochondria-rich cells ; Amphibian skin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Procaine, a tertiary amine, has previously been shown to stimulate reversibly transepithelial Na transport across frog skin after application from the epithelial side. In the present study with intracellular recording from principal, i.e. amiloride-sensitive cells, we demonstrate that the stimulation results from increase in apical membrane Na permeability. A second effect of procaine (10–25 mmol/l) in the outside perfusion solution is a reversible increase of transepithelial conductance which drastically exceeds the predicted response of the transcellular Na pathway. It requires presence of chloride on the epithelial side and depends on the non-ionized molecule of procaine. Abolition of apical membrane Na uptake by amiloride or Na-free mucosal inbubation decreases the magnitude but does not prevent the stimulatory effect of procaine. The origin of this gain in conductance from stimulation of a Cl-specific pathway is demonstrated by a highly significant correlation between the increases in electrically determined tissue conductance and partial Cl conductance, obtained from measurements of influx and efflux of Cl-36. Measurements with microelectrodes indicate that the stimulated Cl-specific pathway is distinct from the principal cells. Since procaine activates a conductive pathway with similar response pattern as spontaneously existing Cl conductance, it might be a valuable tool for investigating mode and way of Cl movement across epithelial tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00587717
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Wash out kinetics of Na from the transport pool to the epithelial and corium side of the frog skin (1972)
    Springer
    Pflügers Archiv 337 (1972), S. 285-297 
    Details
    ISSN: 1432-2013
    Keywords: Frog Skin ; Na Transport ; Transport Pool ; Tracer Wash Out ; Ouabain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The wash out kinetics of Na-24 out of the transport pool of the frog skin were followed simultaneously to the epithelial and corium side in control experiments and after inhibition of the Na transport with ouabain. A perfusion system was used which allowed changes of the perfusion chambers within 5 sec between labelling and tracer wash out. In the control, the Na of the transport pool is washed out with a half time of 2.9±0.3 min and 3.2±0.7 min to the corium and the epithelial side, respectively. After ouabain, the half times increased to 8.9±0.9 min and 8.6±1.1 min for the corium and the epithelial wash out. From this observation it is concluded that the transport Na is distributed in an intracellular compartment. The ratio of the two tracer effluxes from the transport pool to the corium and the epithelial sidej 23 * /j 21 * is 30±8 in the control and 4.9±2.0 after ouabain. The wash out to the epithelial side shows an additional fast component (half times 0.70±0.08 min in the control and 0.68±0.13 after ouabain) which is interpreted as wash out of an extracellular compartment. This view is supported by measurements of the wash out of Inulin C-14.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00586646
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Uptake of Br in mitochondria-rich and principal cells of toad skin epithelium (1988)
    Springer
    Pflügers Archiv 412 (1988), S. 305-313 
    Details
    ISSN: 1432-2013
    Keywords: Amphibian skin ; Anion transport ; Cl conductance-Electron microprobe analysis ; Cellular electrolyte concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To elucidate the route of transepithelial Cl transport across amphibian skins, electrolyte concentrations and uptake of Br in different epithelial cell types of toad skin were determined using electron microprobe analysis. Under short-circuited conditions, Cl concentrations were about 10 mmol/kg ww lower in MR-cells (23.9±9.6 mmol/kg ww) than in principal cells and showed a large scatter. After unitateral substitution of Br for Cl in the bathing solutions, principal cells exchanged Br for Cl only from the serosal side, whereas variable amounts of Br were gained in MR-cells from either side. The ratio of Br to Cl concentrations in MR-cells averaged 0.35 and 0.81 after incubation with NaBr-Ringer's on the apical or serosal side, respectively. After activation of transepithelial anion conductance by serosa-positive voltage-clamping to 100 mV, uptake of Br from the apical side was increased in MR-cells compared with short-circuited conditions. On the average, the ratio of cellular Br to Cl concentrations was 1.38, but the variation among individual MR-cells from the same tissue was considerable. In MR-cells with large uptake of Br and voltageactivated conditions, the sum of Br and Cl concentrations was higher than the Cl concentration under control conditions. The increase of anion content was associated by increase of the Na and corresponding decrease of the K concentrations. The MR-cells were swollen as indicated by the decrease in the cellular dry weight content from 22.2±2.5 to 17.1±4.2 g/100 g. The principal cells contained 3.5±2.6 mmol/kg ww Br after voltage activation of anion conductance which appears to be taken up from the lateral intercellular spaces across the basolateral membrane. The data indicate that principal cells are not involved in transepithelial Cl transport. The MR-cells, although representing a heterogeneous cell population, might be a site for electrodiffusional transepithelial Cl movement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582513
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Analysis of sodium compartments and fluxes in frog skin (1974)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 281 (1974), S. 281-294 
    Details
    ISSN: 1432-1912
    Keywords: Sodium Transport ; Frog Skin ; Compartment Analysis ; Transport Pool
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The path of the transepithelial Na transport through the frog skin was investigated by the use of compartment analysis. Therefore tracer wash-out kinetics from the preloaded epithelium to both sides of the skin and time course of tracer uptake at the epithelial side were measured under control conditions and after alteration of transport parameter by amiloride, ouabain and incubation at 0°C. In all experiments the skins were short-circuited throughout and the SCC registered. The results indicate that the major part of the Na involved in transport is already transported and located in an extracellular compartment, possibly the intercellular space between the epithelial cells. The decisive step of the transepithelial transport seems to be located at the outer epithelial border of the cell layer since entrance of Na into the skin is similarly altered by all inhibitors of transport. Two additional compartments which are labelled from the epithelial side are detectable. The Na content of the compartment with the lowest exchange rate is increased by ouabain and 0° C but remains unchanged after amiloride. It might be located intracellularly but is not responsible for transepithelial transport. The actual transport pool must be very small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00500597
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    Paper (German National Licenses)
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