Ascorbic acid transport and accumulation in human neutrophils

Journal Article · Wed Nov 15 04:00:00 EST 1989 · Journal of Biological Chemistry; (USA)

OSTI ID:5102491

Washko, P; Rotrosen, D; Levine, M ^[1]

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1. National Institute of Diabetes, Digestive, and Kidney Diseases, Bethesda, MD (USA)

The transport, accumulation, and distribution of ascorbic acid were investigated in isolated human neutrophils utilizing a new ascorbic acid assay, which combined the techniques of high performance liquid chromatography and coulometric electrochemical detection. Freshly isolated human neutrophils contained 1.0-1.4 mM ascorbic acid, which was localized greater than or equal to 94% to the cytosol, was not protein bound, and was present only as ascorbic acid and not as dehydroascorbic acid. Upon addition of ascorbic acid to the extracellular medium in physiologic amounts, ascorbic acid was accumulated in neutrophils in millimolar concentrations. Accumulation was mediated by a high affinity and a low affinity transporter; both transporters were responsible for maintenance of concentration gradients as large as 50-fold. The high affinity transporter had an apparent Km of 2-5 microns by Lineweaver-Burk and Eadie-Hofstee analyses, and the low affinity transporter had an apparent Km of 6-7 mM by similar analyses. Each transporter was saturable and temperature dependent. In normal human blood the high affinity transporter should be saturated, whereas the low affinity transporter should be in its linear phase of uptake.

• OSTI ID: 5102491
• Journal Information: Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 264:32; ISSN JBCHA; ISSN 0021-9258
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIMALS
ASCORBIC ACID
BIOLOGICAL ACCUMULATION
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CARBON ISOTOPES
CHROMATOGRAPHY
DISTRIBUTION
IN VITRO
ISOTOPE APPLICATIONS
ISOTOPE DILUTION
ISOTOPES
LEUKOCYTES
LIQUID COLUMN CHROMATOGRAPHY
MAMMALS
MAN
MATERIALS
MEMBRANE TRANSPORT
NEUTROPHILS
PRIMATES
SEPARATION PROCESSES
SUBCELLULAR DISTRIBUTION
TRACER TECHNIQUES
VERTEBRATES
VITAMINS