Abstract
Ascorbic acid (0.57 mM) caused a slow decline in the free (acid-soluble) cystine content of skin fibroblasts from 6 cystinotic patients of 58.6% (range 48-75%) over a 3 day period. The cystine content then remained at this level as long as ascorbic acid was added every 24 hours. When ascorbic acid was removed, the cystine content returned to its original value in 2-3 days. Dehydroascorbic acid, the oxidation product of ascorbic acid, caused a similar reduction in cystine content of cystinotic fibroblasts. Thus, the effect of ascorbic acid is not related to its reducing properties.
Cystinotic fibroblasts preloaded with 35S-cystine rapidly released 35S when treated with dithiothreitol (DTT) but not when treated with ascorbic acid. When cystinotic fibroblasts were depleted of cystine with DTT, the cystine reaccumulated 20% more slowly with dehydroascorbic acid (0.57 mM) in the media. Thus, ascorbic acid and dehydroascorbic acid appear to act by slowing the entry of cystine into the cystine pool of cystinotic fibroblasts and not by increasing the release of cystine from this pool.
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Kroll, W., Schneider, J. REDUCTION OF THE FREE-CYSTINE CONTENT OF CYSTINOTIC FIBROBLASTS BY ASCORBIC ACID AND DEHYDROASCORBIC ACID. Pediatr Res 8, 390 (1974). https://doi.org/10.1203/00006450-197404000-00303
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DOI: https://doi.org/10.1203/00006450-197404000-00303