Effect of Adrenalectomy and of Adrenocortical Hormones on RNA Turnover in a Variety of Subcellular Fractions of Rat Liver

Abstract

(1) The turnover of RNA was examined by following the loss of radioactivity after a single injection of 14C-orotic acid in nuclei, mitochondria, smooth endoplasmic reticulum, rough endoplasmic reticulum, free polysomes, total ribosomes, and sRNA from rat liver. The half-lives of the RNA of various rat liver fractions were found to be 8.7, 6.5, 6.4, 5.4, 4.4, 4.9, and 4.8 days, respectively.(2) In adrenalectomized rats there was a significant decrease in turnover rate. This suggests a slower synthesis of RNA under steady-state conditions. The corresponding values were 12.0, 8.5, 6.5, 6.9, 5.8, 6.1, and 5.9 days.(3) Daily administration of corticosterone or hydrocortisone to adrenalectomized rats restored the turnover rate to normal. Aldosterone was without effect.(4) Aggregate RNA polymerase of rat liver nuclei was decreased by adrenalectomy and restored by corticosterone or hydrocortisone. Aldosterone was without effect.