Characterization of ascorbic acid uptake by isolated rat kidney cells

Journal Article · Tue Jan 01 04:00:00 EST 1991 · Journal of Nutrition; (USA)

OSTI ID:6056562

Bowers-Komro, D M; McCormick, D B ^[1]

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1. Emory Univ. School of Medicine, Atlanta, GA (USA)

Isolated kidney cells accumulated L(1-14C)ascorbic acid in a time-dependent manner and reached a steady state after 15 min at 37 degrees C. Initial velocity for uptake was over 300 pmol/mg protein per min when cells were separated from the bathing solution using a density gradient established during centrifugation. The uptake process was saturable with an apparent concentration at half maximal uptake of 36 mumols/L. Ascorbate uptake was reduced by metabolic inhibitors and was temperature dependent. Although ascorbic acid is an acid anion at pH 7.4, uptake did not appear to be inhibited by other acid anions such as p-aminohippurate and probenecid; however, involvement of the ion gradient established by Na+, H(+)-adenosine triphosphatase could not be confirmed. Replacing the sodium ion with other monovalent ions reduced the accumulation of ascorbate significantly. Isoascorbic and dehydroascorbic acids inhibited ascorbate uptake (34 and 13 mmol/L, respectively), whereas high concentrations of glucose showed some stimulation. These findings indicated that ascorbic acid is reabsorbed by the kidney in a sodium-dependent active transport process that is not common to other acid anions and has some specificity for the ascorbic acid structure.

• OSTI ID: 6056562
• Journal Information: Journal of Nutrition; (USA), Journal Name: Journal of Nutrition; (USA) Vol. 121:1; ISSN 0022-3166; ISSN JONUA
• Country of Publication: United States
• Language: English

Related Subjects

550501* -- Metabolism-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALDEHYDES
ANIMALS
ANIONS
ASCORBIC ACID
ATP
BODY
CARBOHYDRATES
CARBON 14 COMPOUNDS
CATIONS
CENTRIFUGATION
CHARGED PARTICLES
CHROMATOGRAPHY
GLUCOSE
HEXOSES
INHIBITION
IONS
ISOTOPE APPLICATIONS
KIDNEYS
LABELLED COMPOUNDS
LIQUID COLUMN CHROMATOGRAPHY
MAMMALS
MEMBRANE TRANSPORT
METABOLISM
MONOSACCHARIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
RATS
RODENTS
SACCHARIDES
SEPARATION PROCESSES
STEADY-STATE CONDITIONS
TIME DEPENDENCE
TRACER TECHNIQUES
VERTEBRATES
VITAMINS