The mechanism of coupled transport of sodium and chloride in isolated urinary bladder of the trout.

Fossat, B.; Lahlou, B.

doi:10.1113/jphysiol.1979.sp012926

Cited by 26 publications

(15 citation statements)

References 20 publications

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“…Furthermore, net transport of either species is at least partially dependent on the presence of the other (22). A similar interdependence of Na and C1 absorption has been described in the trout urinary bladder (24). However, the flounder bladder differs from many other epithelia that absorb NaCl neutrally in at least one important aspect.…”

Section: Introductionmentioning

confidence: 63%

Sodium chloride absorption by the urinary bladder of the winter flounder. A thiazide-sensitive, electrically neutral transport system.

Stokes¹

1984

J. Clin. Invest.

136

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Abstract. The urinary bladder of the winter flounder absorbs NaCl by a process independent of the transepithelial voltage. In contrast to most other epithelia which have a neutral NaCl-absorptive system, the flounder bladder has a high transepithelial resistance. This feature simplifies analysis of the cellular transport system because the rate of ion transfer through the paracellular pathway is rather low. Experiments were designed to distinguish among three possible mechanisms of neutral NaCl absorption: (a) Na/K/2Cl cotransport; (b) parallel Na/H and Cl/OH exchange; (c) and simple NaCl cotransport. A clear interdependency of Na and Cl for net absorption was demonstrated. NaCl absorption was not dependent on mucosal K and was minimally sensitive to loop diuretics. Thus a Na/K/2Cl transport system was unlikely. The mechanism was not parallel exchange as evidenced by insensitivity to amiloride and to 4,4'-diisothiocyano-2,2'-disulfonic stilbene, an inhibitor of anion exchange. In addition, inhibitors ofcarbonic anhydrase had no effect. Net absorption was almost completely abolished by hydrochlorothiazide (0.1 mM). Its action was rapid, reversible, and effective only from the mucosal surface. Metolazone, a structurally dissimilar diuretic in the benzothiadiazide class had qualitatively similar actions. The Dr. Stokes is an Established Investigator of the American Heart Association.

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Section: Introductionmentioning

confidence: 63%

Sodium chloride absorption by the urinary bladder of the winter flounder. A thiazide-sensitive, electrically neutral transport system.

Stokes¹

1984

J. Clin. Invest.

136

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“…All these experiments were performed at ambient temperature (20)(21)(22) (Fossat & Lahlou, 1979b for both Na+ and C1-. There is a linear relationship in all cases, demonstrated by a high correlation coefficient (P < 0001) and revealing the presence of diffusive components with increase in direct proportion to the electrical gradient.…”

Section: Methodsmentioning

confidence: 99%

Ion flux changes induced by voltage clamping or by amphotericin B in the isolated urinary bladder of the trout.

Fossat¹,

Lahlou²

1982

The Journal of Physiology

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SUMMARY1. When bathed with Ringer solutions on both sides in Ussing chambers, isolated urinary bladders of trout carry out an electrically silent transport of Na+ and Clions from mucosa to serosa. In the present experiments, an electrical gradient was set up across the epithelium mounted under these conditions either by using a voltage-clamp technique or by submitting the mucosal side to the polyene antibiotic Amphotericin B 2. With stable potential differences between -40 and + 40 mV applied to the tissue, both unidirectional fluxes (Jms and Jsm) for Na+ and for Cl-varied as a function of the electrical gradient. This indicates that a sizeable fraction of these ionic exchanges is due to passive diffusion across a low-resistance pathway.3. Amphotericin B (40 ,sg/ml.) applied to the mucosal side induced an immediate and large (up to 50 mV, serosa positive) potential difference and a sustained diminution in tissue resistance. These effects were strictly Na+-dependent and were reduced in the presence of ouabain. Therefore they are due to increased passive entry of Na+ along its electrochemical gradient across the cellular apical membrane. 4. The effect of Amphotericin B was enhanced when Cl-was replaced by an impermeant anion such as gluconate. Therefore the shunting effect of Cl-on the induced potential observed in the control conditions appears to be due to an increase in Cl-permeability across an anion pathway. Flux data indicate that this pathway is transcellular.

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“…A serosa positive change in E; may occur following amphotericin B given the hypertonic nature of NaCl transport (Fossat & Lahlou, 1977) and the apparent anion selectivity of the shunt pathway (Fossat & Lahlou, 1979a). However, we calculate that little change in Ri occurs and furthermore transepithelial Cl-fluxes are not modified by amphotericin B (Fossat & Lahlou, 1982 (Fossat & Lahlou, 1982).…”

Section: Effects Of Amphotericin B On Electrical Parametersmentioning

confidence: 86%

“…The electroneutral mode of NaCl co-transport is associated with a null transepithelial potential, however, in the presence of amphotericin B a transient Vt and short-circuit current are produced (cf. Fossat & Lahlou, 1977, 1979a i I I 1982). For a recent review dealing with the osmoregulatory role of fish urinary bladder see Lahlou & Fossat (1984).…”

Section: Ionic Activities In Trout Bladder 479 Discussionmentioning

confidence: 99%

“…The changes in cellular Na+ and K+ activities were in accordance with their passive redistribution down their electrochemical gradients. INTRODUCTION The mechanism of Na and Cl-transport in the monolayered epithelium of trout urinary bladder was first studied by Lahlou & Fossat in 1971. Isotope flux studies established the mucosal membrane as the site of electroneutral Na: Cl-co-transport and as the rate-limiting barrier to transepithelial active NaCl transport (Fossat & Lahlou, 1979a). Na entry across the mucosal cell membrane was strictly dependent on the presence of Cl-in the mucosal solution and vice versa.…”

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confidence: 99%

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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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The mechanism of coupled transport of sodium and chloride in isolated urinary bladder of the trout.

Cited by 26 publications

References 20 publications

Sodium chloride absorption by the urinary bladder of the winter flounder. A thiazide-sensitive, electrically neutral transport system.

Sodium chloride absorption by the urinary bladder of the winter flounder. A thiazide-sensitive, electrically neutral transport system.

Ion flux changes induced by voltage clamping or by amphotericin B in the isolated urinary bladder of the trout.

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

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