Inhibition of potassium conductance by barium in frog skin epithelium

Nagel, Wolfram

doi:10.1016/0005-2736(79)90289-x

Cited by 148 publications

(68 citation statements)

References 19 publications

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“…Most mammalian cells have as a major component of their membrane voltage a K diffusion potential. Because barium depolarizes cell membranes by reducing K conductance (24)(25)(26)(27)29), the results of the effects of barium (Fig. IV) are consistent with the notion that cell depolarization may be the mechanism whereby an elevation in the ambient K concentration might reduce NaCl absorption.…”

Section: Discussionsupporting

confidence: 77%

Consequences of potassium recycling in the renal medulla. Effects of ion transport by the medullary thick ascending limb of Henle's loop.

Stokes¹

1982

J. Clin. Invest.

116

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Section: Discussionsupporting

confidence: 77%

Consequences of potassium recycling in the renal medulla. Effects of ion transport by the medullary thick ascending limb of Henle's loop.

Stokes¹

1982

J. Clin. Invest.

116

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“…Such behavior is comparable to that of the whole-cell currents in Na medium reported here in the voltage range between reversal and 20 mV. Another similarity is the inhibition of basolateral conductance of the frog skin epithelium by Ba (Nagel, 1979) and quinidine (Abramcheck, Gupta, Sabatini, and Helman, 1982;Van Driessche and Hillyard, 1985; Garda-Diaz, J. F., unpublished data).…”

Section: K Currentssupporting

confidence: 83%

“…This has proven elusive, however, mostly because of technical difficulties. Microelectrode studies have shown that most of the conductance of this membrane is due to K and it is partially inhibited by Ba (Nagel, 1979). No significant C1 conductance has been observed (Gir~tldez and Ferreira, 1984;Nagel, 1985), although it seems that a CI conductance is activated during volume regulatory changes after cell swelling (Ussing, 1982).…”

Section: Introductionmentioning

confidence: 99%

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

1991

The Journal of General Physiology

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A B S T R A C T Whole-cell and single channel currents were studied in cells from frog (R. pipiens and R. catesbiana) skin epithelium, isolated by collagenase and trypsin treatment, and kept in primary cultures up to three days. Whole-cell currents did not exhibit any significant time-dependent kinetics under any ionic conditions used. With an external K gluconate Ringer solution the currents showed slight inward rectification with a reversal potential near zero and an average conductance of 5 nS at reversal. Ionic substitution of the external medium showed that most of the cell conductance was due to K and that very little, if any, Na conductance was present. This confirmed that most cells originate from inner epithelial layers and contain membranes with basolateral properties. At voltages more positive than 20 mV outward currents were larger with K in the medium than with Na or N-methyl-Dglucamine. Such behavior is indicative of a multi-ion transport mechanism. Wholecell K current was inhibited by external Ba and quinidine. Blockade by Ba was strongly voltage dependent, while that by quinidine was not. In the presence of high external CI, a component of outward current that was inhibited by the anion channel blocker diphenylamine-2-carboxylate (DPC) appeared in 70% of the cells. This component was strongly outwardly rectifying and reversed at a potential expected for a C1 current. At the single channel level the event most frequently observed in the cell-attached configuration was a K channel with the following characteristics: inward-rectifying I-V relation with a conductance (with 112.

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“…Effects of K and Ba ions on NaCi transport Recent investigations in renal epithelia have shown a K dependence of Na and Cl uptake (Greger & Schlatter, 1983). We wished to investigate the effects of K+-free Ringer and Ba2+ (a known blocker of K channels in epithelia (Nagel, 1979)) on the uptake of Na+ and Cl-in the fish urinary bladder. Fig.…”

Section: Intracellular Ionic Activitiesmentioning

confidence: 99%

Ion‐selective micro‐electrode studies of the electrochemical potentials in trout urinary bladder.

Harvey¹,

Lahlou²

1986

The Journal of Physiology

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SUMMARY1. Intracellular micro-electtode techniques were used to measure the electrical resistances of the cell membranes and the shunt pathway and intracellular ionic activities in trout urinary bladder when the tissue was incubated in Ringer solution and in the presence of the polyene antibiotic ionophore amphotericin B.2. In control conditions the transepithelial potential was zero and the intracellular potential was -56 mV. The intracellular ionic activities measured with singleand double-barrel ion-sensitive micro-electrodes for the first time in a fish bladder (aka = 16 mm, ak = 87 mm, and a'1 = 21 mM) indicate an active accumulation of K and Cl ions and an active extrusion of Na ions by the cell. The maintenance of intracellular Cl activity above its equilibrium value depended on the presence of Na ions in the mucosal medium, but was independent of the presence of K ions.3. Flat cable analysis yielded values for transepithelial, apical, basolateral and shunt resistances of 197, 2790, 1986 and 205 1 cm-2 respectively. Equivalent circuit analysis using amphotericin B yielded similar values for shunt resistance. The paracellular pathway accounts for 96% of transepithelial current flow and this epithelium may be classified as 'leaky'. The cells are electrically coupled with a space constant of 354 sm.4. Amphotericin B when added to the mucosal solution induced an immediate serosa positive transepithelial potential of about 9 mV and a short-circuit current of 64 1zA cm-2. The Vt was ouabain sensitive and dependent on mucosal Na concentration. The origin of the antibiotic induced transepithelial potential was an increase in the sum of the cell membrane electromotive forces. The apical membrane potential depolarized to -7 mV and its resistance fell to 433 Q cm-2. During the first 10 min ofexposure a'a increased to 80 mm and ak decreased to 7 mm with only a small change in ai1. The changes in cellular Na+ and K+ activities were in accordance with their passive redistribution down their electrochemical gradients. 468 B. J. HARVEY AND B. LAHLOU

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Inhibition of potassium conductance by barium in frog skin epithelium

Cited by 148 publications

References 19 publications

Consequences of potassium recycling in the renal medulla. Effects of ion transport by the medullary thick ascending limb of Henle's loop.

Consequences of potassium recycling in the renal medulla. Effects of ion transport by the medullary thick ascending limb of Henle's loop.

Whole-cell and single channel K+ and Cl- currents in epithelial cells of frog skin.

Ion‐selective micro‐electrode studies of the electrochemical potentials in trout urinary bladder.

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