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  • 1
    Electronic Resource
    Electronic Resource
    The accumulation of copper in Platichthys flesus L. and its effects on plasma electrolyte concentrations (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 20 (1982), S. 0 
    Details
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Copper was shown to accumulate in the gills, liver, kidney and plasma of sea water-adapted and freshwater-adapted Platichthys flesus exposed to elevated ambient concentrations of the metal. Exposure to sublethal concentrations of copper also caused deviations from control values, of the plasma ions sodium and chloride, indicative of impaired ion regulatory capacity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1095-8649.1982.tb03942.x
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  • 2
    Electronic Resource
    Electronic Resource
    The role of the gills in seawater adaptation inAnguilla dieffenbachii (1973)
    Springer
    Journal of comparative physiology 86 (1973), S. 293-313 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mean serum sodium, chloride and potassium concentrations and serum osmotic pressure of freshwaterA. dieffenbachii are 140.4 mmol 1−1,114.0 mmol 1−1, 6.66 mmol 1−1 and 307.7 mOsmol respectively. Gill tissue from freshwater specimens has a water content of 4234 mg g dry wt−1 (80.9% wet wt), a chloride space of 1852 mg water g dry wt−1 (35.2% wet wt) and an intracellular volume of 2449 mg water g dry wt (46.0% wet wt). Estimates of the intracellular sodium and potassium concentrations for the gill tissue of freshwater eels gave values of 28.9 mmol kg intracellular water−1 and 126.5 mmol kg intracellular water−1 respectively. On transfer of the fish to sea water serum concentrations of sodium and chloride and serum osmotic pressure show rapid initial increases followed by a more gradual decline eventually stabilising at new levels some 100 hours after transfer (Fig. 1). The serum sodium, chloride and potassium concentrations and serum osmotic pressure of seawater-adaptedA. dieffenbaehii are 162.8 mmol 1−1, 151.0 mmol 1−1, 6.70 mmol 1−1 and 376.9 mOsmol respectively. On transfer to sea water the water content and chloride space of the gill tissue is reduced and the intracellular volume is initially decreased but is rapidly restored to its original value (Fig. 2, 3). At the same time intracellular sodium and potassium concentrations are increased but the latter is fairly rapidly restored to pre-transfer levels (Fig. 4). The changes in intracellular potassium concentration can be explained largely by the changes in intracellular volume but intracellular sodium concentrations remain high on transfer because of the increased serum sodium concentration. The initial increases in serum concentrations on transfer to sea water are caused partly by the removal of water and partly by the addition of sodium and chloride ions to the internal body fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697915
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  • 3
    Electronic Resource
    Electronic Resource
    The role of the gills in seawater adaptation inAnguilla dieffenbachii (1973)
    Springer
    Journal of comparative physiology 86 (1973), S. 315-321 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Throughout the period of adaptation to sea water the net flux of potassium in the isolated gills remains constant. Initially on transfer to sea water a small net influx of sodium and chloride ions is recorded in the isolated gills. Within a short period of time a net outflux of sodium and chloride is recorded which progressively increases, reaching a maximum after approximately 100 hours of adaptation (Fig. 1). Despite unfavourable osmotic and ionic gradients the functioning of the isolated gill is such that the concentration of the fluid passing through it is actually reduced after some 10–15 hours of seawater adaptation (Fig. 2).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697916
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  • 4
    Electronic Resource
    Electronic Resource
    The role of the gills in seawater adaptation inAnguilla dieffenbachii (1973)
    Springer
    Journal of comparative physiology 86 (1973), S. 323-330 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A comparison of results obtained in studies of serum concentrations in the whole fish with those obtained from preparations of isolated, perfused gills indicates that the rate at which ions are entering the gills of freshwaterAnguilla dieffenbachii on being placed in sea water may only amount to some 10% or less of the calculated rate of addition of ions to the fish as a whole. An additional major route for the entry of ions into the fish on being placed in sea water, other than via the gills, is therefore indicated and, from a consideration of the functioning of the main effector organs of ionic regulation in teleosts, it is concluded that the intestine is the major site of the initial addition of ions to the fish on transfer to sea water. The subsequent reduction and eventual stabilisation of serum ionic concentrations following transfer can be largely explained on both a qualitative and temporal basis by the changes in functioning of the gills, as demonstrated by the isolated, perfused preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697917
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  • 5
    Electronic Resource
    Electronic Resource
    Oxygen consumption in the rectal gland of the dogfishScyliorhinus canicula and the effects of cyclic AMP (1980)
    Springer
    Journal of comparative physiology 136 (1980), S. 39-43 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Oxygen consumption was measured in slices of dogfish (Scyliorhinus canicula) rectal gland tissue and compared with spleen and kidney. Concentrations of dibutyryl cAMP and theophylline that have previously been shown to stimulate secretion from the perfused gland and to produce a large increase in ouabain binding in this tissue, greatly increased oxygen consumption in the rectal gland but were without effect on oxygen consumption in the spleen and the kidney. Addition of theophylline alone increased rectal gland oxygen consumption and no further increase was detected on addition of cAMP at the concentration used (0.05 mmol l−1). Ouabain (10−4 M) significantly decreased oxygen consumption in all three tissues studied and completely abolished the increase in oxygen consumption of the rectal gland produced as a result of the addition of cAMP and theophylline. These findings are discussed in relation to the apparent specific effect of cAMP on the rectal gland and its possible mode of action in this tissue.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688620
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  • 6
    Electronic Resource
    Electronic Resource
    Sites of interactions of surfactants with beta-adrenergic responses in trout (Salmo gairdneri) gills (1987)
    Springer
    Journal of comparative physiology 157 (1987), S. 429-434 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The aims of theis study were to investigate the effects of surfactants on the β-adrenergic responses of the arterio-arterial (lamellar) vascular pathway of isolated gills from the troutSalmo gairdneri. The resistance of the arterio-arterial vasculature was monitored by measuring the input pressure of isolated gills perfused at a constant flow and at constant efferent pressure. Specific β-adrenergic stimulation with isoprenaline produced a dose-dependant reduction in vascular resistance which was mimicked by the presence of cyclic 8-(4-chlorophenylthio) adenosine-3′: 5′-monophosphate (8-cpt cyclic AMP). These results suggest that cyclic AMP is involved as an intracellular second messenger of β-adrenergic regulatory responses of branchial haemodynamics. Surfactants in the perfusate at nominal concentrations of 1.0 μmol l−1 (0.3–0.5 mg l−1) inhibited the response of the branchial tissue to isoprenaline but did not affect the response to 8-cpt cyclic AMP. This suggests that the surfactant effects are the result of events occurring within the cell membrane. Furthermore because the surfactants used affected the efficacy, rather than the affinity, of the isoprenaline response then the mechanism of action is unlikely to be an effect on agonist/receptor interaction but may be further along the stimulus response chain, perhaps affecting receptor/regulatory nucleotide/adenylate cyclase interaction or via direct inhibition of the cyclase itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00691826
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  • 7
    Electronic Resource
    Electronic Resource
    Factors affecting the net fluxes of ions in the isolated perfused gills of freshwaterAnguilla dieffenbachii (1974)
    Springer
    Journal of comparative physiology 94 (1974), S. 297-307 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The net fluxes of sodium, chloride and potassium across the gills of freshwaterAnguilla dieffenbachii were measured using an isolated, perfused preparation. Reductions in the external sodium and chloride concentrations below 1.0 mMol/l resulted in an increasing net outflux of these ions from the gill (Fig. 1) whereas reductions in the internal sodium and chloride concentrations had no significant effect on the net fluxes of these ions (Fig. 2). Increases in the internal sodium and chloride concentrations above those normally found in the serum resulted in increasing net outfluxes of these ions (Fig. 2). Reductions in the internal potassium concentration below 1.0 mMol/l resulted in an increasing net outflux of sodium essentially similar to that obtained on reducing the external sodium concentration (Fig. 3). These results are discussed with reference to the possible active transport of ions across the branchial epithelium of teleosts in fresh water. In particular, the involvement of Na+/K+ exchanges in such transport processes are considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710642
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  • 8
    Electronic Resource
    Electronic Resource
    Bioelectric potentials in the gills of the flounderPlatichthys flesus (1974)
    Springer
    Journal of comparative physiology 94 (1974), S. 321-329 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Measurements of the potential between the external medium and the body fluids of flounders placed in an external medium of Ringer solution have revealed the presence of a steady potential averaging 4·1 mV, inside positive. Isolated gill preparations perfused and bathed in identical Ringer solutions show a similar potential (averaging +6·9 mV) and demonstrate that it cannot be a diffusion potential. Experiments with the perfused preparation have further shown that this potential is dependent on metabolism and is markedly reduced by concentrations of ouabain down to 10−5M (see Fig. 3), thiocyanate down to 5×10−3M (see Fig. 4) and in the absence of potassium in the external medium. It is concluded that the observed potentials result from the active transport of ions across the branchial epithelium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00710644
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  • 9
    Electronic Resource
    Electronic Resource
    The effects of copper on ionic regulation by the gills of the seawater-adapted flounder (Platichthys flesus L.) (1982)
    Springer
    Journal of comparative physiology 149 (1982), S. 83-90 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Potentials measured in isolated, perfused gills fromPlatichthys suggest that the electrogenic ion-pump(s) contribute significantly to the potential measured in seawater. Copper added to the perfusate causes a significant reduction in the potential measured in the isolated gill and it is suggested that this is due to a direct inhibition of the branchial ion pump(s). Vascular resistance was unaffected by the presence of copper. Ouabain-sensitive oxygen consumption was reduced in tissue exposed to copper whereas residual oxygen consumption was unaffected, which suggests that the in vitro action of copper is confined to the Na+, K+ ATPase dependent portion of branchial metabolism. In vitro application of copper to gill homogenates fromPlatichthys flesus adapted to seawater caused a marked reduction in Na+, K+ ATPase activity. In vivo a combination of ouabain binding (to determine the number of enzyme sites), together with measurements of Na+, K+ ATPase activity showed that exposure of the fish to ambient copper in seawater also inhibited enzyme activity. However this response was modulated by a reduction in the sensitivity of the enzyme to copper in copper-treated fish and also responses, possibly of an endocrine nature, modifying Na+, K+ ATPase activity and returning overall enzyme levels to values not significantly different from those in control fish. In addition, this study indicates the importance of obtaining information on both the number of enzyme sites as well as their overall activity in assessing the effects of agents modifying enzymes involved in ion transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00735718
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  • 10
    Electronic Resource
    Electronic Resource
    Peptidergic and adrenergic regulation of electrogenic ion transport in isolated gills of the flounder (Platichthys flesus L.) (1985)
    Springer
    Journal of comparative physiology 155 (1985), S. 471-478 
    Details
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electrogenic potentials measured in isolated gills of seawater-adaptedPlatichthys flesus conform to the current model proposed for salt secretion by teleost chloride cells. Gills perfused and bathed with identical salines maintained a stable potential (“blood”-side positive) thought to represent the activity of a chloride pump. Furosemide added to the perfusate (1×10−4 and 5×10−4 mol l−1) caused a large inhibition of the transepithelial potential. Cyclic 8-(4-chlorophenylthio) adenosine-3′:5′-monophosphate (5×10−5 mol l−1) stimulated the transepithelial potential and decreased the arterial vascular resistance. The adenylate cyclase activator forskolin mimicked the effects of the cAMP derivative on branchial vascular resistance and, at low concentrations, on electrogenic ion transport. At high concentration (〉5×10−7 mol l−1) forskolin inhibited the transepithelial potential. These results implicate cAMP as an important intracellualr regulator of both ionoregulatory and haemodynamic functions in the teleost gill. The β-adrenergic agonist isoprenaline administered as injected doses in the perfusate produced a stimulation of the transepithelial potential and a decrease in the arterial vascular resistance. A dose-response analysis showed that half-maximal haemodynamic effects occurred at significantly lower doses of agonist than those required for half-maximal stimulation of the potential. The pancreatic hormone glucagon also caused dose-dependent stimulation of the transepithelial potential but had no effect on arterial vascular resistance. It is suggested that regulation of the rate of branchial monovalent ion excretion may be under peptidergic as well as adrenergic control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00684677
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