Comparison of ribonucleic acid metabolism in tissues of immature and adult rats.

Abstract

The metabolism of RNA in tissues of immature and adult rats was compared following the injection of 3H-cytidine, 20 μc/100 g body weight. The turnover of both nuclear and cytoplasmic RNA was slower in ventral prostate and seminal vesicle than in liver and thymus. The sedimentation profiles of both cytoplasmic and nuclear RNA of all tissues of both immature and adult rats showed 3 peaks. At 30 min after the injection of labeled cytidine all 3 peaks of nuclear RNA were labeled, whereas the cytoplasmic RNA was labeled primarily in the light fraction. By 120 min after the injection of labeled cytidine, tritium was incorporated into the heavier cytoplasmic RNA fractions. Following a 30 min pulse with 3H-cytidine, actinomycin D, 1 mg/kg body weight, inhibited RNA synthesis in the liver but had little or no effect on RNA synthesis in the ventral prostate and seminal vesicle of immature rats. There was no radioactivity in the heavy RNA of the cytoplasm of the liver 90 min after the administration of actinomycin, ...