Effects of Irradiation on Sub-cellular Components: II. Hydroxylation in the Microsomal Fraction

SummaryThe oxidative demethylation of aminopyrine and of p-chloromethylaniline or the hydroxylation of aniline by suspensions of rat-liver microsomes is inhibited after irradiation with doses of electrons or γ-rays in vitro within the range 5–100 krads.There is little fall in activity immediately after irradiation, but after incubation of the microsome suspensions at 4°, 20° and 37°c, substantial decreases in the rates result. The decrease of capacity to demethylate or hydroxylate oxidatively is accompanied by an increase in the lipid peroxide content of the microsomal suspensions. It is considered that peroxidation induced by irradiation causes disintegration of the lipid membranes essential for the integrity of the electron transport system responsible for this oxidative metabolism.