Induction of cystine transport activity in human fibroblasts by oxygen.

摘要: Abstract The transport activity for cystine in cultured human fibroblasts decreased after incubation of the cells under a low oxygen concentration. After 48 h 3% oxygen, Vmax was to less than one-third that control cells, with little change Km. similar observed 10-40 days several times passages. When these oxygen-cultured were incubated room air, enhanced lag about 4 and almost completely restored within 24 h. This restoration required protein synthesis. increased by 50% exposure hyperoxia (40% oxygen). From results it is concluded induced oxygen. In contrast, activities alanine leucine occurred exposed corresponding hypoxia or hyperoxia. Since transported into reduced cysteine readily exits culture medium where autoxidizes cystine, cystine-cysteine cycle across plasma membrane has been postulated. autoxidation markedly slowed down concentration, response concentration regarded as pertinent. Induction may constitute protective mechanism against oxidative stress, which are exposed, providing mainly incorporated glutathione.