Chemical Transport Knockout for Oxidized Vitamin C, Dehydroascorbic Acid, Reveals Its Functions in vivo

EBioMedicine. 2017 Sep:23:125-135. doi: 10.1016/j.ebiom.2017.08.017. Epub 2017 Aug 22.

Abstract

Despite its transport by glucose transporters (GLUTs) in vitro, it is unknown whether dehydroascorbic acid (oxidized vitamin C, DHA) has any in vivo function. To investigate, we created a chemical transport knockout model using the vitamin C analog 6-bromo-ascorbate. This analog is transported on sodium-dependent vitamin C transporters but its oxidized form, 6-bromo-dehydroascorbic acid, is not transported by GLUTs. Mice (gulo-/-) unable to synthesize ascorbate (vitamin C) were raised on 6-bromo-ascorbate. Despite normal survival, centrifugation of blood produced hemolysis secondary to near absence of red blood cell (RBC) ascorbate/6-bromo-ascorbate. Key findings with clinical implications were that RBCs in vitro transported dehydroascorbic acid but not bromo-dehydroascorbic acid; RBC ascorbate in vivo was obtained only via DHA transport; ascorbate via DHA transport in vivo was necessary for RBC structural integrity; and internal RBC ascorbate was essential to maintain ascorbate plasma concentrations in vitro/in vivo.

MeSH terms

  • Animals
  • Ascorbic Acid / metabolism*
  • Biological Transport
  • Cell Membrane
  • Dehydroascorbic Acid / metabolism*
  • Erythrocytes / metabolism
  • Gene Knockout Techniques
  • Glucose / metabolism
  • Hemolysis
  • Mice
  • Mice, Knockout
  • Oxidation-Reduction*
  • Oxidoreductases / genetics
  • Oxidoreductases / metabolism
  • Phenotype
  • Sugar Acids / metabolism

Substances

  • Sugar Acids
  • gulonolactone
  • Oxidoreductases
  • Glucose
  • Ascorbic Acid
  • Dehydroascorbic Acid