Ionic fluxes in isolated epithelial cells of the abdominal skin of the frogLeptodactylus ocellatus

Zylber, Edit A.; Rotunno, Catalina A.; Cereijido, Marcelino

doi:10.1007/bf01868175

Cited by 13 publications

(5 citation statements)

References 36 publications

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“…This is at variance with the results of Nellans and Schultz (1976) who used whole rabbit ileal epithelium and found that only about 40% of the total intracellular potassium is readily exchangeable. It agrees, however, with the results of Zylber et al (1975), who used isolated frog skin epithelial cells. In the presence of lo-' M ouabain potassium influx is strongly inhibited.…”

Section: Resultssupporting

confidence: 91%

Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells

Sepúlveda¹,

Burton²,

Brown³

1982

Journal Cellular Physiology

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Cells isolated from the epithelium of the small intestine are used to study the relationship between amino acid or sugar-coupled sodium transport and potassium uptake through the sodium/potassium pump. Potassium influx is a saturable function of the external potassium concentration. Uptake in the presence of ouabain, a specific pump inhibitor, is greatly reduced. This remaining influx is linearly related to the concentration up to 6 mM potassium. Sugars and amino acids are actively accumulated by the intestinal cells. Their transport is accompanied by an initial extra influx of sodium. Although cells seem to regulate their internal sodium concentrations, this is not accompanied with a concomitant increase in potassium uptake through the pump. Thus L-alanine, 3-0-methyl-D-glucoside, and alpha-methyl-D-glucoside all fail to increase the rate of ouabain-sensitive potassium uptake. A very high coupling ratio of sodium efflux to potassium influx through the pump would be a likely explanation of the present results though they cannot be regarded as conclusive.

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Section: Resultssupporting

confidence: 91%

Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells

Sepúlveda¹,

Burton²,

Brown³

1982

Journal Cellular Physiology

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“…6 are consistent with the notion that extracellular K exchanges with a single pool of intracellular cation, and uptake kinetics are described by a single increasing exponential function. This result is in agreement with other isolated epithelial cells (Zylber, Rotunno & Cereijido, 1975;Sepulveda et al 1982). Similarly the release of K from pre-loaded rabbit enterocytes is best described by a single decreasing exponential.…”

Section: Cell Viabilitysupporting

confidence: 79%

A rabbit jejunal isolated enterocyte preparation suitable for transport studies.

Brown¹,

Sepúlveda²

1985

The Journal of Physiology

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SUMMARY1. A method is described for isolating viable enterocytes from rabbit jejunum. Estimates of sucrase and y-glutamyl transferase activities in cells isolated by this method suggest that they originate from the upper villus only.2. Isolated cells accumulate both oc-methyl-D-glucoside and alanine, maintaining high intracellular concentrations for at least 60 and 40 min respectively. Accumulation of a-methyl-D-glucoside is inhibited by the presence of phloridzin.3. The cells accumulate 42K and 86Rb in an identical manner. This uptake, which is maintained for at least 60 min, is inhibited in the presence of ouabain. Passive efflux of 42K and 86Rb occurs with rate constants which are virtually identical. The efflux follows a single exponential suggesting that it originates from only one intracellular compartment.4. It is suggested that the preparation can be used to study the effect of sugars and amino acids on K efflux. The advantages of using such a preparation are discussed.

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“…This may be a reflection of diffusion barrier(s) presented to ouabain by the frog skin. In support of this point, under comparable conditions, saturation binding does take ---30 min longer for frog skin than red blood cells (Dunham and Hoffman, 1971) or disaggregated cells from frog skin (Zylber et al, 1975). Finally, this delay is consistent with the time it takes mannitol and presumably, ouabain to equilibrate with the extracellular space.…”

Section: Ouabain Binding As a Function Of Initial Iscsupporting

confidence: 62%

Binding of [3H]ouabain to split frog skin: the role of the Na,K-ATPase in the generation of short circuit current.

Cala

Cogswell

Mandel

1978

The Journal of General Physiology

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A s s T R A C X The binding of [SH]ouabain to the serosal side was studied in a chambered preparation of frog skin, free of connective tissue, while the short circuit (I~) was concurrently monitored. Both ouabain binding and 1~ inhibition proceeded as hyperbolic functions of time. A plot of the number of ouabain molecules bound vs. the corresponding values of Iae inhibition (percent) yielded a straight line, yet showed that one-third of the binding occurred before any inhibition of Ise. Upon separation of the skins into two groups based upon initial Ise(l~l)-high, >20 /~A/cm 2 and low, <10 /~A/cm 2, we observed two distinct populations. The high I~t skins bound very little ouabain before inhibition of lsc whereas low Isel skins bound one-half of the total number of sites before exhibiting any inhibition ofl~. These observations strongly suggest that (a) the Na,K-ATPase is directly involved in the generation of Ise, and (b) at low Ise, inhibition of some pumps by ouabain causes a "recruitment" of other pumps to increase their turnover rate and maintain Ise relatively unaffected. In addition, the binding of ouabain also displayed various characteristics that were consistent with known properties of the Na,K-ATPase: (a) increased intracellular K/Na concentrations, whether achieved through the addition of amiloride or removal of Na from the outside medium, led to a significant decrease in ouabain binding rate relative to paired controls; and (b) ouabain binding, either with normal or decreased intracellular Na, was significantly reduced in the presence of elevated K in the serosal bathing medium. Finally, the number of ouabain molecules bound to the frog skins was not correlated with their initial Ise values, indicating that the spontaneous skin-to-skin variation in lae was not related to the number of functional pump sites but, rather, to their turnover rate.

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Ionic fluxes in isolated epithelial cells of the abdominal skin of the frogLeptodactylus ocellatus

Cited by 13 publications

References 36 publications

Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells

Relation between sodium‐coupled amino acid and sugar transport and sodium/potassium pump activity in isolated intestinal epithelial cells

A rabbit jejunal isolated enterocyte preparation suitable for transport studies.

Binding of [3H]ouabain to split frog skin: the role of the Na,K-ATPase in the generation of short circuit current.

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