Changes in Superoxide Production Rate and in Superoxide Dismutase and Glutathione Peroxidase Activities in Subcellular Organelles in Mouse Liver under Exposure to Low Doses of Low-Intensity Radiation

L. S. Vartanyan^*, S. M. Gurevich, A. I. Kozachenko, L. G. Nagler, E. L. Lozovskaya, and E. B. Burlakova

Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, ul. Kosygina 4, Moscow, 117977 Russia; fax: (7-095) 137-4101; E-mail: chembio@glasnet.ru

^* To whom correspondence should be addressed.

Received March 15, 1999; Revision received June 8, 1999

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The functioning of the antioxidant system in mouse liver at increased stationary concentration of active oxygen species induced by whole-body chronic exposure of mice to gamma-irradiation (¹³⁷Cs, 0.6 cGy/day, 9 days) was studied. Synchronous changes (growth with an extreme) in activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) are found that may be considered as evidence in favor of maintenance of regulatory links in the antioxidant system of liver. The superoxide production rate in microsomes and nuclei also changed with an extreme with the rise in accumulated radiation dose. In microsomes the superoxide production rate reached a maximum at lower doses than the activity of Cu,Zn-SOD did. In nuclei the increase in superoxide production rate was not compensated by the rise in Cu,Zn-SOD activity within the studied dose range. The findings indicate some imbalance between production and consumption of superoxide radicals in microsomes and nuclei; in mitochondria these processes are balanced, leading to more resistance to low-dose irradiation.

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KEY WORDS: superoxide dismutase, glutathione peroxidase, superoxide radicals, mouse liver, irradiation, low-dose gamma-irradiation

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