Chloride dependence of active sodium transport in frog skin: the role of intercellular spaces.

Ferreira, Karin T.G.; Hill, B S

doi:10.1113/jphysiol.1978.sp012500

Cited by 15 publications

(11 citation statements)

References 50 publications

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“…Although a very small fraction of Jw might be directly coupled to the inward flux of Na (Kirschner, Maxwell & Fleming, 1960;House, 1964;Ferreira & Hill, 1978;Lau, Parsons, Brady & Feeney, 1979), the flow of Na and water are essentially uncoupled in a tight epithelium such as toad skin. In particular, the large Jw values induced by hydrosmotic agents result from a selective increase in water permeability of the apical membrane and do not depend on a concomitant increase in Na transport, as seen in leaky epithelia.…”

Section: -9+10-2mentioning

confidence: 99%

Osmotic water flow across the abdominal skin of the toad Bufo marinus: effect of vasopressin and isoprenaline

Sousa

Grosso

1982

The Journal of Physiology

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4. Methohexital and propranolol selectively inhibited the hydrosmotic effects of vasopressin and isoprenaline, respectively, whereas amiloride and ouabain had no effect.5. Mutual inhibition was found between vasopressin and isoprenaline in skins very sensitive to vasopressin. In less sensitive skins isoprenaline further increased Jw despite exposure of the epithelia to supramaximal concentrations of vasopressin. 6. Differential reactivity to vasopressin was found between the skin and the bladder taken from the same toad. In some instances, the bladder responded normally to vasopressin while the skin was totally unresponsive, suggesting the presence of osmoregulatory mechanisms exerting a local modulation of the vasopressin action in different target epithelia of the same animal.

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Section: -9+10-2mentioning

confidence: 99%

Osmotic water flow across the abdominal skin of the toad Bufo marinus: effect of vasopressin and isoprenaline

Sousa

Grosso

1982

The Journal of Physiology

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“…Their values for volume flow at normal conditions are the same as those measured by us for R. ridibunda (Ferreira & Hill, 1978) so we have used their values for volume flow at low pH. At pH 7 4, J, the fluid transport, is 0-69 1d.…”

Section: Discussionmentioning

confidence: 87%

“…Fischbarg & Whittembury (1978), who found that its rate was doubled by lowering the mucosal pH; Ferreira & Hill (1978) obtained similar rates of fluid transport for frog skin at normal pH. In order to calculate the osmolarity of the emergent fluid we decided to measure sodium fluxes at low and normal pH in open circuit as the water fluxes were measured also in open-circuit conditions.…”

Section: Resultsmentioning

confidence: 99%

The effect of low external pH on properties of the paracellular pathway and junctional structure in isolated frog skin.

Ferreira¹,

Hill²

1982

The Journal of Physiology

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SUMMARY1. Undirectional and net fluxes of Na, Cl and mannitol were measured across the isolated short-circuited frog skin when the mucosal surface was bathed with Ringer solution at normal (7 4) or low (2 5) pH. When this solution was changed from normal to low pH, there was a marked increase in both influx and backflux of Cl and mannitol. Na backflux increased markedly but Na influx did not, resulting in a substantial decrease in net flux.2. In open-circuit conditions at low pH both undirectional fluxes of Na increased and the potential across the skin dropped by a third.3. The total conductance, Gt and the short-circuit current, ISc increased when the mucosal solution was changed from normal to low pH. The structural integrity of the 'tight junctions' in the epithelium was disrupted by the low pH treatment and at least 50 % of the junctions examined showed a separation of the two, previously opposed, membranes.4. It has been shown previously that when a low pH solution bathes the mucosal surface the total and shunt conductance increase; the present results demonstrate that under these conditions the short-circuit current no longer provides a good estimate of the net Na flux. We present calculations to show that protons can be the carriers for the extra charge transfer.5. Using our values for net Na flux in open circuit and published values for the solute-linked volume flow, J, it could be shown that the osmolarity of the absorbate decreased at low pH.

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“…Thus for sodium and chloride it can be calculated from tracer experiments (Ussing & Windhager, 1964), but other ions may contribute to the shunt conductance. Or, the cellular sodium conductance can be eliminated by the sodium channel inhibitor, amiloride (Ferreira & Hill, 1978). However, the chloride conductance of the epithelium is drastically reduced by this procedure (see Kristensen, 1978).…”

Section: Discussionmentioning

confidence: 99%

Determination of the electromotive force of active sodium transport in frog skin epithelium (Rana temporaria) from presteady-state flux ratio experiments

Eskesen

Ussing

1985

J. Membrain Biol.

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The presteady-state influxes and effluxes of sodium across frog skin epithelium have been determined as a function of time while all electrophysiological parameters were maintained constant. The fluxes measured were resolved in the fractions which have passed a pathway through the cells and those that have used a paracellular pathway. The procedure is based on the theory that all presteady-state flux ratios have to be equal to the steady-state flux ratio if only one pathway is involved. The flux ratios for the transcellular route were used to calculate the electromotive force of the sodium pump. The calculation hinges on the assumptions (a) that both influx and efflux have to pass through the sodium pump and (b) that single file diffusion of sodium is not taking place anywhere along the path. The validity of both assumptions is discussed. Our calculated values for the electromotive force of the sodium pump EaNa vary between 146 and 200 mV, which is in agreement with the energy of the ATP/ADP system. There is a distinct indication that, as the electrochemical gradient for sodium opposing the transport is being increased, the emf increases towards an asymptotic value around 200 mV. The relation between the value of EaNa and the cellular phosphorylation potential for ATP is discussed.

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Chloride dependence of active sodium transport in frog skin: the role of intercellular spaces.

Cited by 15 publications

References 50 publications

Osmotic water flow across the abdominal skin of the toad Bufo marinus: effect of vasopressin and isoprenaline

Osmotic water flow across the abdominal skin of the toad Bufo marinus: effect of vasopressin and isoprenaline

The effect of low external pH on properties of the paracellular pathway and junctional structure in isolated frog skin.

Determination of the electromotive force of active sodium transport in frog skin epithelium (Rana temporaria) from presteady-state flux ratio experiments

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