A chloride requirement for Na+-dependent amino-acid transport by brush border membrane vesicles isolated from the intestine of a mediterranean teleost (Boops salpa) |
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Authors: | Gérard Bogé Alain Rigal |
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Affiliation: | Laboratoire Maritime de Physiologie, Institut Michel Pacha, 83500 Tamaris-sur-Mer France |
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Abstract: | The uptake of d-glucose, 2-aminoisobutyric acid and glycine was studied with intestinal brush border membrane vesicles of a marine herbivorous fish: Boops salpa. The uptake of these three substances is stimulated by an Na+ electrochemical gradient (). For glucose, an increase of the electrical membrane potential generated by a concentration gradient of the liposoluble anion, SCN?, increases the Na+-dependent transport. This responsiveness to the membrane potential was confirmed by valinomycin. Differently from glucose, uptake of glycine and 2-aminoisobutyric acid requires, besides the Na+ gradient, the presence of Cl? on the external side of the vesicles. In the absence of Cl?, amino acid uptake is not stimulated by the Na+ gradient and is not influenced by an electrical membrane potential generated by SCN? gradient () or by a K+ diffusion potential (). This Cl? requirement differs from the Na+ requirement, since a Cl? gradient () does not result in an accumulation of glycine or 2-aminoisobutyric acid similar to that produced by an Na+ gradient. |
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Keywords: | Amino acid transport Brush border membrane (Teleost intestine) |
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