Basal-lateral-plasma-membrane vesicles and brush-border-membrane vesicles were isolated from rat kidney cortex by differential centrifugation followed by free-flow-electrophoresis. Ca2+ uptake into these vesicles was investigated by a rapid filtration method. Both membranes show a considerable binding of Ca2+ to the vesicle interior, making the analysis of passive fluxes in uptake experiments difficult. Only the basal-lateral-plasma-membrane vesicles exhibit an ATP-dependent pump activity which can be distinguished from the activity in mitochondrial and endoplasmic reticulum by virtue of the different distribution during free-flow electrophoresis and its lack of sensitivity to oligomycin. The basal-lateral plasma membranes contain in addition a Na+/Ca2+-exchange system which mediates a probably rheogenic counter-transport of Ca2+ and Na+ across the basal cell border. The latter system is probably involved in the secondary active Na+-dependent and ouabain-inhibitable Ca2+ reabsorption in the proximal tubule, the ATP-driven system is probably more important for the maintenance of a low concentration of intracellular Ca2+.
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Research Article| March 15 1979
Calcium ion transport across plasma membranes isolated from rat kidney cortex
Biochem J (1979) 178 (3): 549–557.
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P Gmaj, H Murer, R Kinne; Calcium ion transport across plasma membranes isolated from rat kidney cortex. Biochem J 15 March 1979; 178 (3): 549–557. doi: https://doi.org/10.1042/bj1780549
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