The radioprotective effects of certain heavy metals are due to the induction of metallothionein synthesis. However, magnesium, which does not induce metallothionein, also shows a similar radioprotective effect. Thus, some factor other than metallothionein may contribute to the radioprotective effects of metals. In this study, metallothionein, glutathione, glutathioneperoxidase, catalase and superoxide dismutase were examined in mice injected with magnesium or manganese to elucidate the mechanism of the radioprotective effect. Magnesium affected none of the antioxidative factors examined. Manganese increased metallothionein content in the liver but not in the kidneys, brain or intestinal mucosa. The other factors were not affected by manganese. These results suggest that the radioprotective effect of magnesium is not mediated by the activation of antioxidative systems in the body.
The water culture experiment of Houttuynia cordata of the medicinal plant was carried out, and basic study on137Cs accumulation characteristic and internal circulation in H.cordata in the fruiting stage was investigated since the flowering season. H. cordata accumulated 80 % of137Cs absorbed unlike K to the root, rhizome, terminal bud of the underground part for the rhizome reproduction. 137Cs content to the young leaf, spike, involucre increased in the flowering season. Thereafter, 137Cs was recirculated to the developing organs in second generations such as the rhizome and bud.