Kinetic asymmetry of renal Na super(+) -L-lactate cotransport. Characteristic parameters and evidence for a ping pong mechanism of the trans-stimulating exchange by pyruvate

Brush border vesicles prepared from horse renal cortex were used to study the kinetic properties of the Na super(+)-L-lactate carrier on the outer and inner faces of the membrane. Two methods were applied for these measurements (in the absence of an electrical gradient): a direct method using influx...

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Bibliographic Details
Published in:The Journal of biological chemistry 1990-01, Vol.265 (1), p.292-299
Main Authors: Mengual, R, Schlageter, M-H, Sudaka, P
Format: Article
Language:English
Subjects:
kidney
lactic acid
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Summary:Brush border vesicles prepared from horse renal cortex were used to study the kinetic properties of the Na super(+)-L-lactate carrier on the outer and inner faces of the membrane. Two methods were applied for these measurements (in the absence of an electrical gradient): a direct method using influx and efflux kinetics, and an indirect method applied to trans-stimulated influx kinetics using membrane vesicles preloaded with various pyruvate concentrations (the latter enabled us to observe simultaneously the inner and outer carrier properties. These asymmetric properties are related to the AS glide sequential model (A and S being Na super(+) and lactate, respectively) proposed previously for the Na-L-lactate cotransport and to a different accessibility of the organic solute but not of the sodium on the two membrane faces.
ISSN:0021-9258