Ascorbic acid levels in aqueous and vitreous humors of the rabbit: effects of inflammation and ceruloplasmin.

A HPLC method for determination of ascorbic acid and dehydroascorbic acid in plasma and aqueous and vitreous humors of rabbits is described. Values for total ascorbic acid concentration found in this study are in agreement with those of previous investigators. Endotoxin-induced ocular inflammation caused a decrease in the concentration of ascorbic acid in the aqueous humor and an increase in the vitreous humor. The additional lack of correlation between levels of ascorbic acid in normal aqueous and vitreous humors from the same uninflamed eye indicates that the aqueous humor is not the source of vitreal ascorbic acid. The copper concentration of the aqueous humor is increased during ocular inflammation, most likely due to the influx of ceruloplasmin from plasma when the blood-aqueous barrier is disrupted. Ceruloplasmin caused a decrease in the amount of ascorbic acid in the aqueous humor in vitro and the vitreous humor in vivo. The presence of ceruloplasmin in the aqueous humor during inflammation thus may contribute to the decreased concentration of ascorbic acid in this fluid.