Induction of radical scavenging ability and protection against radiation-induced damage to microsomal membranes following low-dose irradiation

PURPOSE: To investigate changes in rat liver cytosolic radical scavenging ability and in microsomal membrane function following low doses of radiation. MATERIALS AND METHODS: Wistar rats were irradiated with 1-50 cGy of X-rays and liver cytosolic radical scavenging ability was determined using DPPH, a stable free radical. Liver microsomal drug metabolizing activity was determined using hexobarbital as a substrate. Cytosolic antioxidants and microsomal enzymes were spectrophotometrically determined. RESULTS: Irradiation of rats at around 5-10 cGy induced liver cytosolic radical scavenging ability and a considerable increase in this ability at 5 cGy was observed for 3 days after irradiation. Glutathione reductase was suggested as a candidate of cytosolic antioxidants. Radiation-induced damage to liver microsomal drug metabolizing enzyme activity was suppressed by preirradiation with 5 cGy, mainly by protecting cytochrome P-450. CONCLUSIONS: Low doses of radiation increased cytosolic radical scavenging ability and resulted in protection of microsomal membrane function which is easily damaged by radiation-induced free radicals.