Effects of Ionizing Radiation and Partial Hepatectomy on Messenger RNA Synthesis

Summary

Newly synthesized messenger RNA, as measured by a 40 min uptake of the radioactive precursor (6-¹⁴C) orotic acid, was studied in the regenerating livers of non-irradiated and gamma-irradiated (1800 rad) adrenal-intact and adrenal-ectomized rats 24 and 48 hours after partial hepatectomy. Two groups of rats, one with and one without adrenal glands, were each divided into four subgroups: (1) control rats, (2) irradiated rats, (3) partially hepatectomized rats and (4) irradiated, partially hepatectomized rats. The radioactive profile of polyribosome formation and distribution was determined by sucrose density gradient centrifugation (10–40 per cent). The result of this study indicates that ionizing radiation decreases the synthesis of newly formed messenger RNA in regenerating livers of adrenal-intact rats. However, adrenalectomy largely abolished that inhibition. These data suggest that the decrease in messenger RNA synthesis may be explained by the disturbance of adrenal hormones induced by partial hepatectomy and ionizing radiation.