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

P. van der Valk, J. J.P. Gille, L. H.W. van der Plas, J. F. Jongkind, A. Verkerk, A. W.T. Konings, H. Joenje*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Further characteristics of an oxygen-tolerant variant of Chinese hamster ovary cells (CHO-99) capable of stable proliferation at 99% O2/1% CO2, an O2 level that is lethal to the parental line (CHO-20), are described. Previous work has revealed that CHO-99 cells have 2- to 4-fold increased activities of superoxide dismutases, catalase and glutathione peroxidase, and substantially increased relative volumes of mitochondria and peroxisomes. To document possible additional mechanisms of O2 tolerance we compared CHO-20 cells growing at 20% O2 (normoxia) and CHO-99 cells at 99% O2 (normobaric hyperoxia). We show the following: (1) the estimated total (oxidative and glycolytic) ATP production in CHO-99 cells was 36% decreased. ATP production through oxidative phosphorylation was 52% lower in CHO-99 cells, while the relative contribution from glycolysis was increased from 6% to 30%. The ATP content was 29% lower in CHO-99 cells, the adenylate energy charge being also significantly decreased, indicating that energy production through oxidative phosphorylation is compromised in CHO-99 cells. Cyanide-resistant respiration was 4-fold higher in CHO-99 cells, probably reflecting, at least partly, the increased peroxisomal activity in these cells. (2) The level of reduced glutathione was several fold increased in CHO-99 cells, oxidized glutathione being unaltered; (NADPH + NADP+) levels were elevated 2.7-fold, while the ratio of NADPH to NADP+ was increased almost two-fold. These changes were associated with a 50% increased metabolism of glucose through the hexose monophosphate pathway. (3) No evidence was obtained for an increased steady-state level of endogenous lipid peroxidation in CHO-99 cells, in spite of a 50% increased content of polyunsaturated fatty acids in the phospholipid fraction.

Original languageEnglish
Pages (from-to)345-356
Number of pages12
JournalFree Radical Biology and Medicine
Issue number6
Publication statusPublished - 1988

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