Modes of Cl− transport across the mucosal and serosal membranes of urodele intestinal cells

White, J. A.

doi:10.1007/bf01869017

Cited by 14 publications

(5 citation statements)

References 36 publications

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“…The finding that the efflux of Cl-from Necturus enterocytes is dominated by movements across the apical membrane is analogous to that of White (1986) for -Amphiuma small intestine and that-of Zuidem'ab et al (1985) for goldfish intestinal epithelium. The effects of mucosal Cl-replacement on Em in the goldfish are also consistent with the presence of an apical Cl-conductance, although this is not 'thtconclusion reached by the authors.…”

Section: Comparison With Other Epithelial Tissuessupporting

confidence: 50%

“…(Lew, Ferreira & Moura, 1979 (White, 1986; F. Giraldez, F. V. Sepuilveda & D. N. Sheppard, unpublished observations) and the intracellular concentration of Na+ is also very low (our measurements with double-barrelled Na+-selective microelectrodes gave values of 10-6 + 3-8 mm for nine cells with Em = -33-3 + 6-3 mV), eqn (1) can be further simplified for symmetrical concentrations of K+ and 601 F. GIRALDEZ, F. V. SEPULVEDA AND D. N. SHEPPARD Na+ ions in the bathing solutions. In this case the change in cell potential after bathing the mucosal membrane with a low-Cl-solution will be given by: …”

Section: Electrical Arrangementsmentioning

confidence: 99%

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A chloride conductance activated by adenosine 3',5'‐cyclic monophosphate in the apical membrane of Necturus enterocytes.

Giráldez

Sepúlveda

Sheppard

1988

The Journal of Physiology

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SUMMARY1. Intracellular potentials, C1-activity and membrane resistances were measured in Necturus small intestinal epithelium during C1-replacement experiments using conventional or Cl--selective double-barrelled microelectrodes. A Cl-conductance, located in the apical membrane and activated by cyclic nucleotides is demonstrated by ion-substitution experiments.2. The mean mucosal membrane potential (Em) was -35-5 mV. Removal of C1-from the mucosal medium by replacement with gluconate, evoked a sudden depolarization of Em and an immediate increase in the fractional resistance of the mucosal membrane (f(Rm)). The size of the change in Em varied between 3 and 65 mV, corresponding to Cl-to K+ permeability ratios between 0-2 and 20. It was inversely related to the initial f(Rm), which ranged from 0 04 to 0 50.3. Prolonged incubation in low-Cl-solutions led to a reversal of the initial depolarization and to a sustained hyperpolarization accompanied by a marked increase in f(Rm). The new value of Em was close to the K+ equilibrium potential, consistent with a depletion of cellular Cl-and the preponderance of a K+ membrane permeability in the absence of Cl-. This emphasizes the role of Cl-in establishing Em. 4. Removal of mucosal Cl-produced a fast decrease in intracellular Cl-, as measured with Cl--selective microelectrodes. The efflux was consistent with electrodiffusion across the mucosal membrane. Changes in Em paralleled changes in intracellular Cl-activity, indicating the presence of a large Cl-conductance.5. Dibutyryl cyclic AMP or forskolin produced a slow depolarization, a decrease in f(Rm) and an increased change in intracellular potential in low mucosal Cl-which on average corresponds to an approximately 15-fold increase in the relative Clpermeability. These results are consistent with an activation of apical Clconductance.6. The selectivity of Cl-channels of Necturus enterocytes to different anions was obtained from potential measurements. The sequence of permeabilities was SCN-> I-3 Br-> N03-> Cl-> HC03-> gluconate. This is consistent with a model involving a weak interaction of the anions with the selectivity filter.F. GIRALDEZ, F. V. SEPULVEDA AND D. N. SHEPPARD 7. The selectivity of the anion conductance was maintained after activation with cyclic nucleotides, suggesting a single channel for the permeation of the different anions tested, rather than parallel channels.8. Derivatives of 9-anthracene which are potent inhibitors of Cl-channels in other systems failed to block the apical Cl-conductance of Necturus enterocytes. Chloride conductance was also insensitive to furosemide.9. The Cl-channels described here can coexist within a single enterocyte with Na+-dependent amino acid carriers, as demonstrated by the simultaneous presence of depolarizations in response to 0 Cl-conditions and to L-alanine in the same cells. No apparent relation was observed between the size of the two effects.10. The present results provide the first direct evidence for the presence of a Clconductance in the apical membrane o...

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Section: Comparison With Other Epithelial Tissuessupporting

confidence: 50%

Section: Electrical Arrangementsmentioning

confidence: 99%

A chloride conductance activated by adenosine 3',5'‐cyclic monophosphate in the apical membrane of Necturus enterocytes.

Giráldez

Sepúlveda

Sheppard

1988

The Journal of Physiology

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“…A Na-HC03/Cl transport system was first described in the snail neuron (Thomas, 1977), barnacle muscle (Boron et al, 1981), and squid giant axon (Boron & Russell, 1983) and subsequently characterized in the Amphiuma intestinal mucosa (White, 1986) and in cultured bovine corneal endothelium (Jentsch et al, 1985). With the use of Cl and pH-sensitive microelectrodes, this transporter was described in the basolateral membrane of Necturus proximal tubule ).…”

Section: Discussionmentioning

confidence: 99%

Sodium-dependent chloride transport in basolateral membrane vesicles isolated from rabbit proximal tubule

Chen¹,

Verkman²

1988

Biochemistry

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The mechanisms for Cl transport across basolateral membrane vesicles (BLMV) isolated from rabbit renal cortex were examined by using the Cl-sensitive fluorescent indicator 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ). The transporters studied included Cl/base exchange, Cl/base/Na cotransport, K/Cl cotransport, and Cl conductance. Initial rates of chloride influx (JCl) were determined from the measured time course of SPQ fluorescence in BLMV following inwardly directed gradients of Cl and gradients of other ions and/or pH. For a 50 mM inwardly directed Cl gradient in BLMV which were voltage and pH clamped (7.0) using K/valinomycin and nigericin, JCl was 0.80 +/- 0.14 nmol S-1 (mg of vesicle protein)-1 (mean +/- SD, n = 8 separate preparations). In the absence of Na and CO2/HCO3 in voltage-clamped BLMV, JCl increased 56% +/- 5% in response to a 1.9 pH unit inwardly directed H gradient; the increase was further enhanced by 40% +/- 3% in the presence of CO2/HCO3 and inhibited 30% +/- 8% by 100 microM dihydro-4,4'-diisothiocyanostilbene-2,2'-disulfonic acid. Na gradients did not increase JCl in the absence of CO2/HCO3; however, an outwardly directed Na gradient in the presence of CO2/HCO3 increased JCl by 31% +/- 8% with a Na KD of 7 +/- 2 mM. These results indicate the presence of Cl/OH and Cl/HCO3 exchange, and Cl/HCO3 exchange trans-stimulated by Na. There was no significant effect of K gradients in the presence or absence of valinomycin, suggesting lack of significant K/Cl cotransport and Cl conductance under experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…However, the basolateral exit step for anions has not been clearly determined. Recent studies have suggested several possible anion transport mechanisms, many of which are sensitive to stilbenes and furosemide (15)(16)(17)(18)(19)(20). The basolateral membrane quite clearly has a multiplicity of possible transport systems; further studies will be required to resolve the complexity of these systems.…”

Section: Discussionmentioning

confidence: 99%

Electrogenic Anion Absorption in Rabbit Distal Colon

Sellin

Thompson²

1992

Experimental Biology and Medicine

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The mechanisms of anion transport in the rabbit distal colon were investigated in vitro under short-circuit conditions by examining the effects of transport inhibitors (the stilbene derivatives SITS and DIDS) under a variety of conditions. These agents consistently inhibited Jm-sCl: SITS (10(-3) M) reduced both unidirectional chloride fluxes to the same degree and did not alter JnetCl. In contrast, 10(-4) M DIDS had no effect on Js-mCl and had a significant chloride antiabsorptive effect. DIDS had no effect on either tissue cyclic AMP levels or on basal flux of potassium. The effects of SITS and the cyclic AMP-related secretagogue theophylline on Isc were independent. Additionally, there was no significant alteration of intracellular potential difference or apical membrane fractional resistance elicited by SITS during microelectrode impalement of colonic surface epithelial cells. These results suggest a complex mechanism of anion transport in the distal colon, with a component of electrogenic anion absorption inhibited by the stilbenes. The subsequent changes in current, conductance, and chloride fluxes are dependent upon additional, independent anion transport processes. These pharmacologic agents exhibit an antiabsorptive effect, rather than a stimulation of electrogenic chloride secretion.

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Modes of Cl− transport across the mucosal and serosal membranes of urodele intestinal cells

Cited by 14 publications

References 36 publications

A chloride conductance activated by adenosine 3',5'‐cyclic monophosphate in the apical membrane of Necturus enterocytes.

A chloride conductance activated by adenosine 3',5'‐cyclic monophosphate in the apical membrane of Necturus enterocytes.

Sodium-dependent chloride transport in basolateral membrane vesicles isolated from rabbit proximal tubule

Electrogenic Anion Absorption in Rabbit Distal Colon

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