Article
Na+-H+ exchange activity in brush-border membrane vesicles isolated from chick small intestine
Author/s | Ferrero, María Isabel
Cano Rodríguez, María Mercedes Ilundáin Larrañeta, María Anunciación Ana |
Department | Universidad de Sevilla. Departamento de Fisiología |
Publication Date | 1995 |
Deposit Date | 2020-04-24 |
Published in |
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Abstract | This study was undertaken to investigate the presence of a Na+{single bond}H+ antiporter in brush-border membrane vesicles (BBMV) isolated from chick small intestine. An outwardly directed proton gradient (pH 5.5 inside, ... This study was undertaken to investigate the presence of a Na+{single bond}H+ antiporter in brush-border membrane vesicles (BBMV) isolated from chick small intestine. An outwardly directed proton gradient (pH 5.5 inside, 7.5 outside) stimulated Na+ uptake into BBMV and resulted in a transient accumulation. No accumulation was observed in the absence of a proton gradient. Voltage clamping the membrane with K+ and valinomycin decreased the Na+ overshoot. Amiloride inhibited pH gradient-driven Na+ uptake in a dose-dependent manner with an IC50 of 44 μM. The relationship between pH gradient-driven Na+ uptake and external Na+ concentration followed simple, saturating Michaelis-Menten kinetics. Eadie-Hofstee analysis of the pH gradient-driven Na+ uptake indicated a single transport system with a Vmax of 33 nmol/mg protein per 15 s and a Km for Na+ of 12 mM. The initial rate of pH-driven Na+ uptake increased as the intravesicular pH decreased, with a Hill coefficient close to 1. These findings indicate that BBMV isolated from chicken small intestine posses a Na+{single bond}H+ exchanger. This exchanger does not appear to be the one involved in cell pH regulation. |
Project ID. | PB89-0616 |
Citation | Ferrero, M.I., Cano Rodríguez, M.M. y Ilundáin Larrañeta, M.A.A. (1995). Na+-H+ exchange activity in brush-border membrane vesicles isolated from chick small intestine. Biochimica et Biophysica Acta - Biomembranes, 1235 (2), 313-316. |
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