martes, 29 de mayo de 2012

La glucosa inhibe l acaptación de la vitamina C por los neutrófilos, o sea que produce inmunodepresión

J OURNAOFL B IOLOGICACLH EMISTRY 33, NVol.. 267, Issue of November 25, pp. 23568-23574,1992

in U. S. A.

of Ascorbic Acid Transport in Human Neutrophils

by Glucose*

(Received for publication, May 22, 1992)

Philip Washko and Mark Levine$

From the Laboratory
of Cell Biology and Genetics, National Institute of Diabetes and Digestiue and Kidney Diseuses, National

of Health, Bethesda, Maryland 20892

Because of the structural similarity between glucose

and ascorbic acid, we investigated the effect of glucose

on uptake and accumulation of ascorbic acid in isolated

normal human neutrophils. Ascorbic acid accumulation

was determined using high-performance liquid

chromatography with coulometric electrochemical detection,

in conjunction with liquid scintillation spectrometry.

Ascorbic acid accumulation in neutrophils is

mediated by a high and a low affinity transport activity.

In neutrophils from different volunteers, glucose

inhibited uptake and accumulation of ascorbic acid by

both transport activities 3-9-fold. The mechanism of

inhibition was different for each transport activity:

inhibition of the high affinity transport activity was

noncompetitive, while inhibition of the low affinity

activity was competitive. Glucose-induced inhibition

of both ascorbic acid transport activities occurred in

neutrophils of all donors tested and was fully reversible.

Although the mechanism of ascorbic acid accumulation

appeared to be different than that for glucose

transport, other monosaccharides and glucose transport

inhibitors also inhibited ascorbic acid accumulation.

These are the first data to suggest that ascorbic

acid accumulation in neutrophils can be regulated by

compounds of similar structure.

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