Characterization of oxygen-tolerant Chinese hamster ovary cells: II. Energy metabolism and antioxidant status

摘要: Abstract Further characteristics of an oxygen-tolerant variant Chinese hamster ovary cells (CHO-99) capable stable proliferation at 99% O 2 /1% CO , level that is lethal to the parental line (CHO-20), are described. Previous work has revealed CHO-99 have 2- 4-fold increased activities superoxide dismutases, catalase and glutathione peroxidase, substantially relative volumes mitochondria peroxisomes. To document possible additional mechanisms tolerance we compared CHO-20 growing 20% (normoxia) (normobaric hyperoxia). We show following: (1) estimated total (oxidative glycolytic) ATP production in was 36% decreased. through oxidative phosphorylation 52% lower cells, while contribution from glycolysis 6% 30%. The content 29% adenylate energy charge being also significantly decreased, indicating compromised cells. Cyanide-resistant respiration higher probably reflecting, least partly, peroxisomal activity these (2) reduced several fold oxidized unaltered; (NADPH + NADP ) levels were elevated 2.7-fold, ratio NADPH almost two-fold. These changes associated with a 50% metabolism glucose hexose monophosphate pathway. (3) No evidence obtained for steady-state endogenous lipid peroxidation spite polyunsaturated fatty acids phospholipid fraction.