Dehydroascorbate transport in human chondrocytes is regulated by hypoxia and is a physiologically relevant source of ascorbic acid in the joint

McNulty AL, Stabler TV, Vail TP, McDaniel GE, Kraus VB · Arthritis and Rheumatism

The second route in, and it opens wider exactly where cartilage lives. Chondrocytes take up the oxidised form of vitamin C through glucose transporters, chiefly GLUT-1, and that uptake is up-regulated at the low oxygen tensions found inside cartilage. Modelled contribution: 26% of intracellular ascorbate in osteoarthritic chondrocytes and 94% in rheumatoid — the oxidised form matters most where inflammation is worst.

Population

Human chondrocytes, plus synovial fluid from osteoarthritis patients

Intervention

Radiolabelled dehydroascorbate transport under varying oxygen tensions, with GLUT-1 and GLUT-3 knockdown

Limitations

The tissue percentages are modelled from transport kinetics and measured synovial fluid ratios rather than measured inside cartilage. Cell culture.