Chloride transport in apical membrane vesicles from bovine tracheal epithelium: Characterization using a fluorescent indicator

1988 ◽  
Vol 104 (3) ◽  
pp. 233-239 ◽  
Author(s):  
P. Fong ◽  
Nicholas P. Illsley ◽  
J. H. Widdicombe ◽  
A. S. Verkman
Keyword(s):  
Apical Membrane ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Tracheal Epithelium ◽  
Fluorescent Indicator ◽  
Apical Membrane Vesicles

scholarly journals Chloride transport in human proximal colonic apical membrane vesicles

1996 ◽  
Vol 1280 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Ravish J. Mahajan ◽  
Melissa L. Baldwin ◽  
James M. Harig ◽  
Krishnamurthy Ramaswamy ◽  
Pradeep K. Dudeja
Keyword(s):  
Apical Membrane ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Apical Membrane Vesicles

Evidence for the Existence of a Distinct SO–4-OH–Exchange Mechanism in the Human Proximal Colonic Apical Membrane Vesicles and Its Possible Role in Chloride Transport

2001 ◽  
Vol 226 (10) ◽  
pp. 912-918 ◽  
Author(s):  
Sangerta Tyagip ◽  
Reena J. Kavilaveettil ◽  
Waddah A. Alrefai ◽  
Shadwan Alsafwah ◽  
Krishnamurthy Ramaswamy ◽  
...  
Keyword(s):  
Apical Membrane ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Exchange Mechanism ◽  
Apical Membrane Vesicles

Sulfate transport in apical membrane vesicles isolated from tracheal epithelium

1987 ◽  
Vol 253 (3) ◽  
pp. C416-C425 ◽  
Author(s):  
A. Elgavish ◽  
D. R. DiBona ◽  
P. Norton ◽  
E. Meezan
Keyword(s):  
Anion Exchanger ◽  
Apical Membrane ◽  
Membrane Vesicles ◽  
Anion Transport ◽  
Proton Gradient ◽  
Tracheal Epithelium ◽  
Sulfate Transport ◽  
Sulfate Uptake ◽  
Transport Inhibitors ◽  
Apical Membrane Vesicles

Sulfate uptake in apical membrane vesicles isolated from bovine tracheal epithelium is shown to occur into an osmotically sensitive intravesicular space, via a carrier-mediated system. This conclusion is based on three lines of evidence: 1) saturation kinetics; 2) substrate specificity; and 3) inhibition by the anion transport inhibitors SITS and DIDS. The affinity of the transport system is highest in low ionic strength media (apparent Km = 0.13 mM) and decreases in the presence of gluconate (apparent Km = 0.68 mM). Chloride appears to cis-inhibit sulfate uptake and to trans-stimulate sulfate efflux. Cis-inhibition and trans-stimulation studies with a variety of anions indicate that this exchange system may be shared by HCO3-, S2O3(2-), SeO4(2-), and MoO4(2-) but not by H2PO4- or HAsO4(2-). Studies indicate that protons may play two distinct roles in sulfate transport in this system. 1) Their possible modifier role is suggested by the fact that protons affect SO2-4 transport in an uncompetitive manner. 2) The possibility that the proton gradient may act as an energy source for a secondary active transport is indicated by the fact that the imposition of a proton gradient stimulates a transient movement of sulfate in to the tracheal apical membrane vesicle, against its concentration gradient, causing an "overshoot" phenomenon. Our studies show that the carrier-mediated system can function in the absence of chloride. The overshoot observed in the presence of a proton gradient (OH- gradient) indicates that under those conditions the mechanism of transport may be a SO4(2-)-OH- exchange. The fact that chloride cis-inhibits and trans-stimulates SO4(2-) transport indicates that SO2-4 uptake may also occur via a SO4(2-)-Cl- exchange. Studies carried out so far do not enable us to conclude unequivocally whether the tracheal apical membrane system displays two distinct carrier activities (SO4(2-)-Cl-; SO4(2-)-OH-) or one anion exchanger, which like the erythrocyte anion exchanger, may interact with SO4(2-), Cl-, and H+. The fact that the anion transport inhibitors DIDS and SITS inhibit SO4(2-) transport in the presence or absence of chloride suggests that the latter possibility may be the case.

Monoclonal antibody against conductive chloride transport in pig ileal apical membrane vesicles

1996 ◽  
Vol 271 (2) ◽  
pp. C478-C485 ◽  
Author(s):  
K. J. Racette ◽  
S. E. Gabriel ◽  
K. J. Gaspar ◽  
G. W. Forsyth
Keyword(s):  
Monoclonal Antibodies ◽  
Ion Channel ◽  
Apical Membrane ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Chloride Ion ◽  
Transmembrane Conductance Regulator ◽  
Protein Species ◽  
Western Blots ◽  
Apical Membrane Vesicles

Conductive chloride transport in the small intestine is an important factor controlling fluid movement from the blood to the lumen of the gut. Several proteins with potential conductive chloride ion channel activity are expressed in the enterocyte cell population. However, it is not clear whether one or more than one protein species is normally responsible for mediating conductive chloride transport. We have raised monoclonal antibodies that inhibit conductive chloride transport in apical membrane vesicles prepared from porcine ileal enterocytes. These monoclonal antibodies have been used to identify a unique protein involved with this conductive chloride transport. Here, we report that anti-chloride conductance monoclonal antibodies did not detect any antigen in Western blots of enterocyte apical membrane protein. Dot blotting and immunoprecipitation experiments indicated that the antigen recognized by these monoclonal antibodies was not the cystic fibrosis transmembrane conductance regulator. The antigen was localized to both villus and crypt regions of ileum on immunohistochemistry. A 90-kDa protein species was immunoprecipitated from a primary enterocyte cell line by these monoclonal antibodies. This 90-kDa protein may be a chloride ion channel or may play some regulatory role in conductive chloride transport in enterocyte apical membrane vesicles.

scholarly journals Epithelial chloride channel. Development of inhibitory ligands.

1987 ◽  
Vol 90 (6) ◽  
pp. 779-798 ◽  
Author(s):  
D W Landry ◽  
M Reitman ◽  
E J Cragoe ◽  
Q Al-Awqati
Keyword(s):  
Binding Site ◽  
Chloride Channel ◽  
Chloride Channels ◽  
Ethacrynic Acid ◽  
Apical Membrane ◽  
Chloride Transport ◽  
Membrane Vesicles ◽  
Kidney Cortex ◽  
High Affinity Binding Site ◽  
Apical Membrane Vesicles

Chloride channels are present in the majority of epithelial cells, where they mediate absorption or secretion of NaCl. Although the absorptive and secretory channels are well characterized in terms of their electrophysiological behavior, there is a lack of pharmacological ligands that can aid us in further functional and eventually molecular characterization. To obtain such ligands, we prepared membrane vesicles from bovine kidney cortex and apical membrane vesicles from trachea and found that they contain a chloride transport process that is electrically conductive. This conductance was reduced by preincubating the vesicles in media containing ATP or ATP-gamma-S, but not beta-methylene ATP, which suggests that the membranes contain a kinase that can close the channels. We then screened compounds derived from three classes: indanyloxyacetic acid (IAA), anthranilic acid (AA), and ethacrynic acid. We identified potent inhibitors from the IAA and the AA series. We tritiated IAA-94 and measured binding of this ligand to the kidney cortex membrane vesicles and found a high-affinity binding site whose dissociation constant (0.6 microM) was similar to the inhibition constant (1 microM). There was a good correlation between the inhibitory potency of several IAA derivatives and their efficacy in displacing [3H]IAA-94 from its binding site. Further, other chloride channel inhibitors, including AA derivatives, ethacrynic acid, bumetanide, and DIDS, also displaced the ligand from its binding site. A similar conductance was found in apical membrane vesicles from bovine trachea that was also inhibited by IAA-94 and AA-130B, but the inhibitory effects of these compounds were weaker than their effects on the renal cortex channel. The two drugs were also less potent in displacing [3H]IAA-94 from the tracheal binding site.

Distribution and regulation of apical Cl/anion exchanges in surface and crypt cells of rat distal colon

1999 ◽  
Vol 276 (1) ◽  
pp. G132-G137 ◽  
Author(s):  
Vazhaikkurichi M. Rajendran ◽  
Henry J. Binder
Keyword(s):  
Spatial Distribution ◽  
Concentration Gradient ◽  
Apical Membrane ◽  
Membrane Vesicles ◽  
Distal Colon ◽  
Ph Homeostasis ◽  
Rat Distal Colon ◽  
Na Depletion ◽  
Crypt Cells ◽  
Apical Membrane Vesicles

Na depletion inhibits electroneutral Na-Cl absorption in intact tissues and Na/H exchange in apical membrane vesicles (AMV) of rat distal colon. Two anion (Cl/HCO3 and Cl/OH) exchanges have been identified in AMV from surface cells of rat distal colon. To determine whether Cl/HCO3 and/or Cl/OH exchange is responsible for vectorial Cl movement, this study examined the spatial distribution and the effect of Na depletion on anion-dependent 36Cl uptake by AMV in rat distal colon. These studies demonstrate that HCO3 concentration gradient-driven36Cl uptake (i.e., Cl/HCO3 exchange) is 1) primarily present in AMV from surface cells and 2) markedly reduced by Na depletion. In contrast, OH concentration gradient-driven36Cl uptake (i.e., Cl/OH exchange) present in both surface and crypt cells is not affected by Na depletion. In Na-depleted animals HCO3 also stimulates36Cl via Cl/OH exchange with low affinity. These results suggest that Cl/HCO3 exchange is responsible for vectorial Cl absorption, whereas Cl/OH exchange is involved in cell volume and/or cell pH homeostasis.

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