Cl/HCO3 exchange in the basolateral membrane domain of rat jejunal enterocyte

Orsenigo, M.; Tosco, M.; Faelli, A.

doi:10.1007/bf01871360

Cited by 28 publications

(14 citation statements)

References 47 publications

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“…Previously we demonstrated that (1) in rat jejunum anion exchange is restricted to the basolateral membrane and does not accept ¬_lactate (Orsenigo et al 1991), and (2) rat jejunal basolateral membranes contain a proton-lactate symporter (Orsenigo et al 1997). This evidence, together with the present results, supports the hypothesis that MCT1 is a major route for lactic acid efflux across the basolateral membrane of rat jejunum.…”

Section: Rt-pcr Experimentsmentioning

confidence: 99%

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

Orsenigo

Tosco

Bazzini

et al. 1999

Experimental Physiology

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summaryWe have functionally expressed and identified a monocarboxylate transporter (MCT1) from rat jejunal enterocyte and we provide evidence for its basolateral localization. Poly(A)¤ RNA isolated from rat jejunum was injected into Xenopus laevis oocytes and expression of a proton-lactate symporter was investigated by means of ¬_[14 C]lactate uptake. The existence of an endogenous capacity for ¬_lactate transport was demonstrated; when, however, oocytes were injected with jejunal mRNA, an expressed ¬_lactate uptake was seen which differed from the endogenous transporter since it was significantly pH dependent. After sucrose density gradient fractionation, the highest expression of the pH-dependent lactate uptake was detected with the mRNA size fraction of about 2-3 kb in length. The substrate specificity, stereoselectivity and sensitivity to pCMBS (an organomercurial thiol reagent that modifies cysteine residues) of the expressed transport were in good agreement with results previously obtained using isolated jejunal basolateral membranes. Using the reverse transcriptase-polymerase chain reaction, the presence of mRNA coding for the MCT1 isoform was demonstrated in jejunal enterocytes. These data, together with previous results, suggest that MCT1 is a major route for lactate efflux across the basolateral membrane of rat jejunum; this is in contrast to current opinion which restricts the presence of MCT1 to the apical membrane of the whole small intestine.

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Section: Rt-pcr Experimentsmentioning

confidence: 99%

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

Orsenigo

Tosco

Bazzini

et al. 1999

Experimental Physiology

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“…Chlorine uptake (n) at dpi: % Activation 0 3 (12,24,31,40,42). Accordingly, we investigated the effects on 36 Cl Ϫ uptake of imposing gradients of either chloride, pH, or both together in the presence of short-circuiting conditions to assess an electroneutral mechanism.…”

Section: CLmentioning

confidence: 99%

Rotavirus Infection Stimulates the Cl⁻Reabsorption Process across the Intestinal Brush-Border Membrane of Young Rabbits

Lorrot

Martin

Vasseur

2003

J Virol

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Rotavirus is a major cause of infantile gastroenteritis worldwide. However, the mechanisms underlying fluid and electrolyte secretion associated with diarrhea remain largely unknown. We investigated the hypothesis that loss of Cl ؊ into the luminal contents during rotavirus infection may be caused by a dysfunction in the chloride absorptive capacity across the intestinal brush-border membrane (BBM). The luminal Cl ؊ concentrations in the entire small intestine of young rabbits infected with lapine rotavirus decreased at 1 and 2 days postinfection (dpi), indicating net Cl ؊ absorption. At 7 dpi, luminal Cl ؊ concentrations were slightly increased, indicating a moderate net Cl ؊ secretion. By using a rapid filtration technique, 36 Cl uptake across BBM was quantified by modulating the alkali-metal ion, electrical, chloride, and/or proton gradients. Rotavirus infection caused an identical, 127% ؎ 24% increase in all Cl ؊ uptake activities (Cl ؊ /H ؉ symport, Cl ؊ conductance, and Cl ؊ /anion exchange) observed across the intestinal BBM. The rotavirus activating effects on the symporter started at 1 dpi and persisted up to 7 dpi. Kinetic analyses revealed that rotavirus selectively affected the capacity parameter characterizing the symporter. We report the novel observation that rotavirus infection stimulated the Cl ؊ reabsorption process across the intestinal BBM. We propose that the massive Cl ؊ reabsorption in villi could partly overwhelm chloride secretion in crypt cells, which possibly increases during rotavirus diarrhea, the resulting imbalance leading to a moderate net chloride secretion.

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“…We found a Cl/ HCO 3 exchanger (which does not accept lactate) and conductive pathways for both Cl and HCO 3 , but we had no evidence for Na-(HCO 3 ) n cotransport [5][6][7]. The Cl/HCO 3 exchanger probably moves HCO 3 into the serosal fluid, therefore extruding a base into the serosal subepithelial spaces.…”

Section: Discussionmentioning

confidence: 87%

“…Since in the jejunal tract of the intestine HCO 3 absorption occurs (at least in rat, dog, and man) [2][3][4], Cl/HCO 3 exchange should mediate HCO 3 efflux into the serosal compartment. Up to now jejunal basolateral Cl/HCO 3 antiport has been characterized using isolated membrane vesicles [1,[5][6][7][8], demonstrated in isolated enterocytes from the same intestinal tract [9] and not found in the subsequent intestinal tract [10]. Since the maximal activation of Cl/HCO 3 antiport is at about pH 7.2 (preliminary results from our laboratory), under normal conditions the anion exchanger should be involved in bicarbonate transport towards the blood stream.…”

Section: Introductionmentioning

confidence: 99%

Cl/HCO<sub>3</sub> Antiport Affects H-Lactate Symport Activity at the Basolateral Pole of Jejunum Enterocyte

Faelli

Orsenigo

Verri

et al. 1998

Cell Physiol Biochem

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Background/Aims: Under normal conditions the jejunal tract of the rat intestine absorbs HCO₃. A basolateral Cl/HCO₃ exchange, evidenced by means of membrane vesicles, could be involved in this process. Aim of this study was to investigate the anion exchange activity in the whole jejunal tract, where various transport systems could interact. Methods: In the jejunal tract of rat intestine everted and incubated in vitro, the experimental conditions set up minimized loss of CO₂ from the serosal solution, where pH and pCO₂ were determined together with fluid and electrolyte transintestinal transport. Results: The serosal pCO₂ increase and pH decrease, evident during the experiment, could be antagonized by enhancing the 4,4-diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS) concentrations in the serosal fluid. Moreover high DIDS concentration affected fluid, sodium, lactate, bicarbonate and, although in the opposite direction, chloride transport, whilst they were ineffective on K flux. Conclusion: These results give evidence that in the basolateral membrane the inhibition of Cl/HCO₃ antiport causes a diminution of lactic acid movement. Therefore we can hypothesize that Cl/HCO₃ antiport facilitates basolateral H-lactate symport in order to carry endogenous lactic acid towards the blood stream.

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Cl/HCO3 exchange in the basolateral membrane domain of rat jejunal enterocyte

Cited by 28 publications

References 47 publications

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

Rotavirus Infection Stimulates the Cl⁻Reabsorption Process across the Intestinal Brush-Border Membrane of Young Rabbits

Cl/HCO<sub>3</sub> Antiport Affects H-Lactate Symport Activity at the Basolateral Pole of Jejunum Enterocyte

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Cl/HCO3 exchange in the basolateral membrane domain of rat jejunal enterocyte

Cited by 28 publications

References 47 publications

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

A Monocarboxylate Transporter MCT1 is Located at the Basolateral Pole of Rat Jejunum

Rotavirus Infection Stimulates the Cl−Reabsorption Process across the Intestinal Brush-Border Membrane of Young Rabbits

Cl/HCO<sub>3</sub> Antiport Affects H-Lactate Symport Activity at the Basolateral Pole of Jejunum Enterocyte

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Rotavirus Infection Stimulates the Cl⁻Reabsorption Process across the Intestinal Brush-Border Membrane of Young Rabbits