TY - JOUR
T1 - Characterization of oxygen-tolerant Chinese hamster ovary cells. II. Energy metabolism and antioxidant status
AU - van der Valk, P.
AU - Gille, J. J.P.
AU - van der Plas, L. H.W.
AU - Jongkind, J. F.
AU - Verkerk, A.
AU - Konings, A. W.T.
AU - Joenje, H.
N1 - Funding Information: Acknowledgments--Ttehceh nicaal ssistancoef Cees van Tilburg ls gratefullya cknowledgedW. e thank H. G. Keizer and J. van Rijn for critically readingt he manuscriptT.h is researchw as supported by the NetherlandCs ancerF oundation(g rantI KA 82-13), and by the Foundatiofno r FundamentBali ologicalR esearc(hB ION), which is subsidizebdy the NetherlandOsr ganizatiofno r the Advancement of Pure Research(Z WO).
PY - 1988
Y1 - 1988
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0023944626&partnerID=8YFLogxK
U2 - https://doi.org/10.1016/0891-5849(88)90086-X
DO - https://doi.org/10.1016/0891-5849(88)90086-X
M3 - Article
C2 - 3384344
SN - 0891-5849
VL - 4
SP - 345
EP - 356
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
IS - 6
ER -