Citrate and succinate transport in proximal tubule cells.
Am J Physiol Renal Physiol
; 278(3): F492-8, 2000 Mar.
Article
en En
| MEDLINE
| ID: mdl-10710554
ABSTRACT
Urinary citrate, which inhibits calcium nephrolithiasis, is determined by proximal reabsorption via an apical dicarboxylate transporter. Citrate is predominantly trivalent at physiological pH, but citrate(-2) is transported at the apical membrane. We now demonstrate that low-Ca solutions induce transport of citrate(-2) and succinate in opossum kidney cells. With 1.2 mM extracellular Ca, citrate uptake was pH insensitive and not competed by succinate(-2). In contrast, with low extracellular Ca, citrate uptake increased twofold, was inhibited by succinate (and other dicarboxylates), was stimulated by lowering extracellular pH (consistent with citrate(-2) transport), and increased further by lowering extracellular Mg. The effect of Ca was incrementally concentration dependent, between 0 and 1.2 mM. The effect of Ca was not simply complexation with citrate because succinate (which is complexed significantly less) was affected by Ca similarly. Incubation of cells for 48 h in a low-pH media increased citrate transport (studied at control pH) more than twofold, suggesting induction of transporters.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Ácido Cítrico
/
Ácido Succínico
/
Túbulos Renales Proximales
Límite:
Animals
Idioma:
En
Revista:
Am J Physiol Renal Physiol
Asunto de la revista:
FISIOLOGIA
/
NEFROLOGIA
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos