Induction of radical scavenging ability and suppression of lipid peroxidation in rat liver microsomes following whole-body, low-dose X-irradiation.
OBJECTIVE
To investigate changes in radical scavenging ability and lipid peroxidation in liver microsomal membranes and cooperative suppression of lipid peroxidation by microsomal and cytosolic radical scavengers, 24 h after whole-body, low-dose X-irradiation of rats.


METHODS
Male Wistar rats were irradiated with 1-50 cGy of X-rays. Liver microsomal radical scavenging ability was determined using the trapping ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH), a stable free radical. Microsomal alpha-tocopherol (Vit.E) content was determined using an electrochemical detector. Microsomal glutathione peroxidase (GPx) activity was determined as the consuming rate of NADPH. Microsomal lipid peroxidation was determined by the thiobarbituric acid method.


RESULTS
Low molecular weight radical scavenging ability of rat liver microsomes increased 24 h after whole-body, low-dose X-irradiation when alpha-tocopherol was included, showing a maximum level at 5-10 cGy. Microsomal GPx activity also increased 24 h after 5 cGy irradiation. The lipid peroxidation level in microsomes decreased, showing a maximal suppression at 5 cGy. High-dose irradiation-induced microsomal lipid peroxidation was strongly suppressed cooperatively by microsomal and cytosolic antioxidants induced by low-dose irradiation.


CONCLUSIONS
Low doses of radiation induce increases in liver microsomal antioxidants, which in turn result in enhanced suppression of microsomal lipid peroxidation cooperatively with cytosolic antioxidants induced by low-dose irradiation.
Yukawa
Osami
O
Radiation Hazards Research Group, Research Center for Radiation Safety, National Institute of Radiological Sciences, Anagawa, Chiba-shi, Japan.
Nakajima
Tetsuo
T
Miura
Yuri
Y
Ueda
Junichi
J
Ozawa
Toshihiko
T
D000818:Animals; D004307:Dose-Response Relationship, Radiation; D016166:Free Radical Scavengers / Q000378:metabolism*; D015227:Lipid Peroxidation / Q000502:physiology* / Q000528:radiation effects*; D008099:Liver / Q000378:metabolism / Q000528:radiation effects; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism / Q000528:radiation effects*; D011829:Radiation Dosage; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000502:physiology / Q000528:radiation effects; D014916:Whole-Body Irradiation
D016166:Free Radical Scavengers