EFFECTS OF X-IRRADIATION ON THE HEXOBARBITAL METABOLIZING ENZYME SYSTEM OF RAT LIVER MICROSOMES.
Rept. for 1 Dec 65-31 May 66.
CHICAGO UNIV ILL TOXICITY LAB
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A study was conducted on the influence of X-ray on the development of a hepatic microsomal oxidase that catalyzes the oxidative detoxification of hexobarbital. Exposure of 23-day old male rats to 400 r of X-ray completely inhibited the rapid increase in enzyme activity that normally occurs at this age in male rats. After three weeks following radiation exposure, reversal of the inhibition was observed. Exposure of only the heads of male rats also resulted in inhibition of the enzyme development in the liver, and hypophysectomized, unirradiated rats failed to exhibit the normal increase in enzyme activity. These findings resembled the results of previous investigations in this laboratory on other microsomal enzymes and provided further evidence that radiation acts on some process involved in the synthesis of increased enzyme activity in the livers of male rats through an indirect mechanism probably involving hormonal regulation of microsome enzyme synthesis. X-irradiation 400 r also inhibited the synthesis of the hexobarbital oxidizing enzyme in the liver of partially hepatectomized male rats. A prolonged duration of action of hexobarbital in irradiated young male rats and hepatectomized, adult rats demonstrated the in vivo effects of inhibition of enzyme synthesis on drug metabolism. Author