The distribution of radioactivity from uracil mustard-2- 14C in the hepatic subcellular particulates and nucleic acids of the rat

Abstract

The concentration of radioactivity in the liver particulates and in the nucleic acids of the liver, kidney, spleen, and small intestine of rats was measured after intravenous uracil mustard-2- 14C. Of the injected radioactivity 2.6% was localized in the liver at 30 minutes; the level gradually declined to 0.26% at 96 hours. The cell sap: particulate ratio was 1.5 at 30 minutes and 0.4 at 96 hours. At most time periods the concentration of radioactivity in the renal nucleic acids was significantly higher than that in the nucleic acids of the liver, spleen, and small intestine. At 1 and 3 hours the concentration of radioactivity in duodenal and jejunal RNA was not significantly different from that in renal RNA and was also higher than the concentration in the liver and spleen. Based upon the concentration of radioactivity, uracil mustard appeared to have reacted with the various nucleic acids in the range of 16,400 to 65,000 nucleotide units per molecule of uracil mustard at 1 2 hour. Only 2–3% of the radioactivity present in the liver cell was localized in nucleic acids. There was, therefore, widespread association of the radioactivity with other cellular constituents.