Studies on chloride permeability of the skin ofLeptodactylus ocellatus: III. Na+ and Cl− effect on electrical phenomena

Boulan, E. Rodríguez; Petery, M. V. Ques-von; Rotunno, Catalina A.; Cereijido, Marcelino

doi:10.1007/bf01870355

Cited by 11 publications

(5 citation statements)

References 31 publications

(39 reference statements)

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“…The slope that we have found at low concentrations (39 mV per decade concentration change) is much lower than the 58 mV pre4icted on the basis of the results of Koefoed-Johnsen and Ussing (1958) but is close to that obtained by other authors (Smith, Martin & Huf, 1973;Nagel, 1977;Rodriguez Boulan et al, 1978). In agreement with various authors (Nagel, 1977;Rodriguez Boulan et al, 1978), we did not find any difference in the slope log Na obtained with NaCI or NazSO~ external solutions at low concentrations. That skins bathed with permeant and nonpermeant anions have the same transepithelial DP (maximum around 10meq) may seem surprising, tt would suggest that chloride entrance which is mainly mediated by the C1-/HCO~ exchange mechanism in this range of low NaC1 concentrations does not contribute to the transepithelial DP.…”

Section: Evidence For Two Sodium and Chloride Transport Componentssupporting

confidence: 78%

“…Such a transepithelial DP dependence of the outer Na concentration has been found by several autl~ors (Steinbacli, 1933;Koefeld-Johnsen & Ussing, 1958;Nagel, 1977), and a tendency of the DP to saturate at high Na concentrations has been generally reported (Steinback, 1933;Brown, 1962;Smith, Martin & Huf, 1973;Rodriguez Boulan et al, 1978). The slope that we have found at low concentrations (39 mV per decade concentration change) is much lower than the 58 mV pre4icted on the basis of the results of Koefoed-Johnsen and Ussing (1958) but is close to that obtained by other authors (Smith, Martin & Huf, 1973;Nagel, 1977;Rodriguez Boulan et al, 1978). In agreement with various authors (Nagel, 1977;Rodriguez Boulan et al, 1978), we did not find any difference in the slope log Na obtained with NaCI or NazSO~ external solutions at low concentrations.…”

Section: Evidence For Two Sodium and Chloride Transport Componentsmentioning

confidence: 92%

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Kinetics of ionic transport across frog skin: Two concentration-dependent processes

Ehrenfeld¹,

Garcia-Romeu²

1980

J. Membrain Biol.

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Sodium and chloride influxes across the nonshort-circuited isolated skin of Rana esculenta were measured at widely varying external ionic concentrations. The curve describing sodium transport has two Michaelis-Menten components linked at an inflection point occurring at an external sodium concentration of about 7 meq. Chloride transport can also be represented by two saturating components. A possible explanation of these kinetics is discussed. At sodium concentrations lower than 4 meq it is possible to define a component of the sodium transport mechanism as having a high affinity for sodium and which is independent of the nature of the external anion. A high affinity for chloride of the chloride transport system functioning at low external concentrations is also found but is significantly different from that of sodium. These systems show the physiological characteristics of the countertransports (Na est(+)/H int(+); Cl ext(-)/HCO 3int(-)) functioning at low external concentrations. At external concentrations higher than 4 meq a low affinity transporting system in which chloride and sodium are linked superimpose on the high affinity compoents. The physiological significance of these results is discussed.

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Section: Evidence For Two Sodium and Chloride Transport Componentssupporting

confidence: 78%

Section: Evidence For Two Sodium and Chloride Transport Componentsmentioning

confidence: 92%

Kinetics of ionic transport across frog skin: Two concentration-dependent processes

Ehrenfeld¹,

Garcia-Romeu²

1980

J. Membrain Biol.

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“…Cereijido and co-workers recently investigated in detail the chloride transport across the skin of the frog Leptodactylus ocellatus Rodriguez-Boulan et al, 1978). Several years ago, Zadunaisky and associates found that significant amounts of chloride are transported in an inward direction across the skin of this frog (Zadunaisky & Candia, 1962;Zadunaisky, Candia & Chiarandini, 1963;Zadunaisky & Fisch, 1964).…”

Section: Discussionmentioning

confidence: 99%

Influence of extracellular Cl concentration on Cl transport across isolated skin ofRana pipiens

1980

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The effect of changes in Cl concentration in the external and/or serosal bath on Cl transport across short-circuited frog skin was studied by measurements of transepithelial Cl influx (JCl13) and efflux (JCl31), short-circuit current, transepithelial potential, and conductance (Gm). JCl13 as well as JCl31 were found to have a saturating component and a component which is apparently linear with Cl concentration. The linear component of JCl31 appears only upon addition of Cl to external medium, and about 3/4 of this component does not contribute to Gm. The saturating component of JCl31 is only 5% of total JCl31 with 115 mM Cl in the serosal medium. Replacement of 115 mM Cl- in external medium by SO4=, NO3-, HCO-3 or I- results in 87-97% reduction of JCl31, whereas replacement with Br- has no effect. As external Cl concentration is raised in steps from 2 to 115 mM, JCl13 and JCl31 increase by the same amount but JCl13 is persistently 0.15 mu eq/cm2hr larger than JCl31. These results indicate that at least 3/4 of linear components of JCl13 and JCl31 proceed via an exchange diffusion mechanism which seems to be located at the outer cell border. The saturating component of JCl13 is involved in active Cl transport in an inward direction, and there is evidence suggesting that Cl uptake across outer cell border, which proceeds against an electrochemical gradient, is electroneutral but not directly linked to Na.

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“…Several studies suggest activation of the skin C1-conductance by external CI ions (Kirschner, 1970;Mandel & Curran, 1972;Alvarado, Dietz & Mullen, 1975;Bruus et al, 1976;Rodriguez-Boulan et al, 1978;Kristensen, 1978;Biber, Walker & Mullen, 1980;Ehrenfeld & Garcia-Romeu, 1980;Kirschner, 1983;Katz & Larsen, 1984;Harck & Larsen, 1985).…”

Section: Introductionmentioning

confidence: 99%

Roles of external and cellular Cl− ions on the activation of an apical electrodiffusional Cl− pathway in toad skin

Procópio

Lacaz-Vieira

1990

J. Membrain Biol.

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This study is concerned with the short-circuit current, Isc, responses of the Cl(-)-transporting cells of toad skin submitted to sudden changes of the external Cl- concentration, [Cl]o. Sudden changes of [Cl]o, carried out under apical membrane depolarization, allowed comparison of the roles of [Cl]o and [Cl]cell on the activation of the apical Cl- pathways. Equilibration of short-circuited skins symmetrically in K-Ringer's solutions of different Cl- concentrations permitted adjustment of [Cl]cell to different levels. For a given Cl- concentration (in the range of 11.7 to 117 mM) on both sides of a depolarized apical membrane, this structure exhibits a high Cl- permeability, P(Cl)apical. On the other hand, for the same range of [Cl]cell but with [Cl]o = 0, P(Cl)apical is reduced to negligible values. These observations indicate that when the apical membrane is depolarized P(Cl)apical is modulated by [Cl]o; in the absence of external Cl- ions, intracellular Cl- is not sufficient to activate P(Cl)apical. Computer simulation shows that the fast Cl- currents induced across the apical membrane by sudden shifts of [Cl]o from a control equilibrium value strictly follow the laws of electrodiffusion. For each experimental group, the computer-generated Isc versus [( Cl]cell - [Cl]o) curve which best fits the experimental data can only be obtained by a unique pair of P(Cl)apical and Rb (resistance of the basolateral membrane), thus allowing the calculation of these parameters. The electrodiffusional behavior of the net Cl- flux across the apical membrane supports the channel nature of the apical Cl- pathways in the Cl(-)-transporting cells. Cl- ions contribute significantly to the overall conductance of the basolateral membrane even in the presence of a high K concentration in the internal solution.

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Studies on chloride permeability of the skin ofLeptodactylus ocellatus: III. Na+ and Cl− effect on electrical phenomena

Cited by 11 publications

References 31 publications

Kinetics of ionic transport across frog skin: Two concentration-dependent processes

Kinetics of ionic transport across frog skin: Two concentration-dependent processes

Influence of extracellular Cl concentration on Cl transport across isolated skin ofRana pipiens

Roles of external and cellular Cl− ions on the activation of an apical electrodiffusional Cl− pathway in toad skin

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