Na+-dependent D-mannose transport at the apical membrane of rat small intestine and kidney cortex
The presence of a Na+/D-mannose cotransport activity in brush-border membrane vesicles (BBMV), isolated from either rat small intestine or rat kidney cortex, is examined. In the presence of an electrochemical Na+ gradient, but not in its absence, D-mannose was transiently accumulated by the BBMV. D-...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2001 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:idus.us.es:11441/95724 |
| Acceso en línea: | https://hdl.handle.net/11441/95724 https://doi.org/10.1016/S0005-2736(01)00322-4 |
| Access Level: | acceso abierto |
| Palabra clave: | Brush-border membrane vesicle Intestine Kidney Sodium/D-mannose |
| Sumario: | The presence of a Na+/D-mannose cotransport activity in brush-border membrane vesicles (BBMV), isolated from either rat small intestine or rat kidney cortex, is examined. In the presence of an electrochemical Na+ gradient, but not in its absence, D-mannose was transiently accumulated by the BBMV. D-Mannose uptake into the BBMV was energized by both the electrical membrane potential and the Na+ chemical gradient. D-Mannose transport vs. external D-mannose concentration can be described by an equation that represents a superposition of a saturable component and another component that cannot be saturated up to 50 μM D-mannose. D-Mannose uptake was inhibited by D-mannose ≫ D-glucose > phlorizin, whereas for α-methyl glucopyranoside the order was D-glucose = phlorizin ≫ D-mannose. The initial rate of D-mannose uptake increased as the extravesicular Na+ concentration increased, with a Hill coefficient of 1, suggesting that the Na+ :D-mannose cotransport stoichiometry is 1:1. It is concluded that both rat intestinal and renal apical membrane have a concentrative, saturable, electrogenic and Na+-dependent D-mannose transport mechanism, which is different from SGLT1. |
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