Transport of glutathione by renal basal-lateral membrane vesicles

Transport of glutathione was studied in membrane vesicles derived from the basal-lateral region of the plasma membrane of rat kidney proximal tubules. The integrity of the vesicle preparation was demonstrated by showing that vesicles were osmotically sensitive, with GSH uptake at equilibrium varying inversely with medium osmolality. Analysis of vesicle content by high-pressure liquid chromatography and competition experiments with glycine and cysteinylglycine confirmed that measured uptake of GSH represented transport of intact tripeptide rather than transport of degradation products. The initial rate of GSH uptake in the presence of either the sodium or potassium salt of the permeant thiocyanate anion showed that the uptake was sodium-dependent. This suggests that a GSH-Na+ cotransport system exists in these membranes.