Tubular Transport of Amino Acids and Small Peptides

Silbernagl, Stefan

doi:10.1002/cphy.cp080241

Cited by 1 publication

(1 citation statement)

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“…GSH is found in an abundance in various mammalian tissues including the epithelium lining the renal proximal tubule (3). The renal epithelial cells, particularly those lining the proximal tubule, exhibit high concentrations (5 mM) of GSH compared with micromolar concentrations that are present in the lumen and peritubular fluid (3,19). In the kidneys of rats, GSH has a short half-life of approximately 3.5 s extracellularly and 29 min intracellularly (10), which is in accordance with the high activity of extracellular ␥-GT localized mainly on the brushborder membrane of proximal tubular epithelial cells.…”

Section: Discussionsupporting

confidence: 57%

Luminal and Basolateral Membrane Transport of Glutathione in Isolated Perfused S1, S2, and S3 Segments of the Rabbit Proximal Tubule

Parks¹,

Zalups²,

Barfuss³

2000

Journal of the American Society of Nephrology

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Abstract. Lumen-to-bath and bath-to-lumen transport rates of glutathione (GSH) were measured in isolated perfused S1, S2, and S3segments of the rabbit proximal tubule. In lumen-to-bath experiments, the perfusion solution contained 4.6 μM3H-GSH with or without 1.0 mM acivicin. In all three segments perfused without acivicin, luminal disappearance rate (JDL) and bath appearance rate (JAB) of3H-GSH were 14.5 ± 0.5 and 2.2 ± 0.8 fmol/min per mm tubule length, respectively. With acivicin present,JDLandJABwere reduced to 1.3 ± 0.4 and 0.5 ± 0.3, respectively, with no differences among segments. Cellular concentrations of3H-GSH in S1, S2, and S3segments when acivicin was absent were 23.1 ± 2.0, 31.7 ± 11.4, and 143.5 ± 17.9 μM, respectively. With acivicin in perfusate, cellular concentrations were reduced but there was no change in the heterogeneity profile. In bath-to-lumen transport experiments (S2segments only), the bathing solution contained 2.3 μM3H-GSH.3H-GSH appearance in the lumen (JAL, fmol/min per mm) and cellular accumulation from the bath were studied with and without acivicin in the perfusate.JALvalues were 3.0 ± 0.2 and 0.2 ± 0.03 while cellular concentrations were 9.5 ± 1.0 and 6.1 ± 0.5 μM, respectively. It is concluded that: (1) GSH is primarily removed from the luminal fluid after degradation to glycine, cysteine, and glutamate, which are absorbed; (2) GSH can be absorbed intact at the luminal membrane; (3) the S3segment has the greatest GSH cellular concentration because its basolateral membrane has less capacity for cell-to-bath transport of GSH; and (4) GSH can be secreted intact from the peritubular compartment into the tubular lumen.

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Section: Discussionsupporting

confidence: 57%