Intestinal ion transport and diarrheal disease

Fondacaro, Joseph D.

doi:10.1152/ajpgi.1986.250.1.g1

Cited by 51 publications

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“…Dysregulation of Cl Ϫ secretion accounts for the diarrheal response that accompanies a number of inflammatory and infectious enteropathies (13,34). Classically, the major regulatory site for Cl Ϫ secretion was envisioned at the level of apical Cl Ϫ channels such as CFTR.…”

Section: Discussionmentioning

confidence: 99%

Phorbol 12-myristate 13-acetate-induced endocytosis of the Na-K-2Cl cotransporter in MDCK cells is associated with a clathrin-dependent pathway

Mykoniatis

Shen

Fedor-Chaiken³

et al. 2010

American Journal of Physiology-Cell Physiology

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Mykoniatis A, Shen L, Fedor-Chaiken M, Tang J, Tang X, Worrell RT, Delpire E, Turner JR, Matlin KS, Bouyer P, Matthews JB. Phorbol 12-myristate 13-acetate-induced endocytosis of the Na-K-2Cl cotransporter in MDCK cells is associated with a clathrin-dependent pathway. Am J Physiol Cell Physiol 298: C85-C97, 2010. First published October 28, 2009 doi:10.1152/ajpcell.00118.2009In secretory epithelial cells, the basolateral Na ϩ -K ϩ -2Cl Ϫ cotransporter (NKCC1) plays a major role in salt and fluid secretion. Our laboratory has identified NKCC1 surface expression as an important regulatory mechanism for Cl Ϫ secretion in the colonic crypt cell line T84, a process also present in native human colonic crypts. We previously showed that activation of protein kinase C (PKC) by carbachol and phorbol 12-myristate 13-acetate (PMA) decreases NKCC1 surface expression in T84 cells. However, the specific endocytic entry pathway has not been defined. We used a Madin-Darby canine kidney (MDCK) cell line stably transfected with enhanced green fluorescent protein (EGFP)-NKCC1 to map NKCC1 entry during PMA exposure. At given times, we fixed and stained the cells with specific markers (e.g., dynamin II, clathrin heavy chain, and caveolin-1). We also used chlorpromazine, methyl-␤-cyclodextrin, amiloride, and dynasore, blockers of the clathrin, caveolin, and macropinocytosis pathways and the vesicle "pinchase" dynamin, respectively. We found that PMA caused dose-and time-dependent NKCC1 endocytosis. After 2.5 min of PMA exposure, ϳ80% of EGFP-NKCC1 endocytic vesicles colocalized with clathrin and ϳ40% colocalized with dynamin II and with the transferrin receptor, the uptake of which is also mediated by clathrin-coated vesicles. We did not observe significant colocalization of EGFP-NKCC1 endocytic vesicles with caveolin-1, a marker of the caveolae-mediated endocytic pathway. We quantified the effect of each inhibitor on PMA-induced EGFP-NKCC1 endocytosis and found that only chlorpromazine and dynasore caused significant inhibition compared with the untreated control (61% and 25%, respectively, at 2.5 min). Together, these results strongly support the conclusion that PMA-stimulated NKCC1 endocytosis is associated with a clathrin pathway. chlorpromazine; dynamin II; transferrin receptor THE SODIUM-POTASSIUM-CHLORIDE COTRANSPORTER NKCC1 is an integral membrane cation-Cl Ϫ cotransporter of the SLC12 family (SLC12A2) that is sensitive to the diuretic bumetanide (9a). NKCC1 is found in nearly all cell types and serves to regulate intracellular ionic composition and cell volume (44).

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Section: Discussionmentioning

confidence: 99%

Phorbol 12-myristate 13-acetate-induced endocytosis of the Na-K-2Cl cotransporter in MDCK cells is associated with a clathrin-dependent pathway

Mykoniatis

Shen

Fedor-Chaiken³

et al. 2010

American Journal of Physiology-Cell Physiology

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“…Na+ would follow passively across the cation-selective junctions between enterocytes, and the luminal NaCl would draw water across the epithelium (Rao & Field, 1983;Donowitz & Welsh, 1986;Fondacaro, 1986;Hardcastle & Hardcastle, 1987).…”

Section: Activation Of Cl-channels In Intact Cellsmentioning

confidence: 99%

Characterization of a phosphorylation‐activated Cl‐selective channel in isolated Necturus enterocytes.

Giráldez

Murray

Sepúlveda

et al. 1989

The Journal of Physiology

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SUMMARY1. The cell-attached and excised inside-out configurations of the patch-clamp technique were employed to probe isolated enterocytes of Necturus maculosus for the presence of Cl--selective channels.2. Chloride-selective channels were rarely observed unless cells were previously stimulated by agonists that raise cyclic AMP. In cell-attached patches forskolin (20 /tM) or dibutyryl cyclic AMP (2 mM) evoked single-channel activity that reversed, depending on the cell, between 9 and 27 mV positive to the spontaneous membrane potential. This is close to the Cl-equilibrium potential in these cells; the singlechannel current-voltage relationship was linear with a unitary slope conductance between 17 and 25 pS (pipettes filled with 100 mM-NaCl).3. Large depolarizing voltage steps also activated Cl-channels in excised insideout membrane patches that were previouslyr quiescent. This mode of activation produced a distinctive single-channel current-voltage relationship with strong outward rectification at depolarizing membrane potentials. Single-channel cord conductance at negative potentials was 15-18 pS and increased to 45 pS at + too mV.4. Altering the Cl-concentration in the bathing solution of excised inside-out patches displaced the observed reversal potential (Erev) to values predicted for Clequilibrium potential. Replacement of K' for Na+ was without effect.5. The effect of different anions upon E,ev was used to determine the channel anion selectivity in excised inside-out patches. The permeability sequence was SCN-> I-> Br-> Cl-> F-> HC03-> gluconate which corresponds to Eisenman's sequence 1. Nether ionic size nor diffusion rates determine the permeation of ions through the channel. 6. In channels activated by depolarization the open probability (PO) was insensitive to changes in the Ca2+ concentration ( < 10-8_10-3 M) bathing the cytoplasmic face of excised inside-out patches. Depolarization was also without marked effect on PO.

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“…In the intestinal epithelia, water secretion and absorption are fundamental aspects of daily activities. 2,3) Water movement across the epithelia is generally driven by an osmotic gradient created by active ion transport. 4) Typically, the epithelial cells absorb water by active Na ϩ uptake which is pumped by Na ϩ -K ϩ ATPase on the serosal side, and secrete water by actively pumping out Cl Ϫ which is powered by the Na…”

mentioning

confidence: 99%

Effect of Ethanol Extracts of Three Chinese Medicinal Plants with Laxative Properties on Ion Transport of the Rat Intestinal Epithelia

Tsai

Chang

2004

Biological & Pharmaceutical Bulletin

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Huomaren increased the short-circuit current of the forskolin-activated ileal epithelia (control). The current augmentation was diminished by the addition of ouabain before the Huomaren extract (ouabain). Addition of bumtanide partially blocked the effect of Huomaren on augmenting the short-circuit current (bumetanide). Values are meanϮ S.D. for 6 individual measurements. Different letters indicate statistically significant different (pϽ0.05) determined using Student's t-test.

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Intestinal ion transport and diarrheal disease

Cited by 51 publications

References 0 publications

Phorbol 12-myristate 13-acetate-induced endocytosis of the Na-K-2Cl cotransporter in MDCK cells is associated with a clathrin-dependent pathway

Phorbol 12-myristate 13-acetate-induced endocytosis of the Na-K-2Cl cotransporter in MDCK cells is associated with a clathrin-dependent pathway

Characterization of a phosphorylation‐activated Cl‐selective channel in isolated Necturus enterocytes.

Effect of Ethanol Extracts of Three Chinese Medicinal Plants with Laxative Properties on Ion Transport of the Rat Intestinal Epithelia

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