STUDIES ON LIVER REGENERATION: I. ¹³¹IODODEOXYURIDINE AS A PRECURSOR of DNA IN NORMAL and REGENERATING RAT LIVER

Abstract

Abstract. 131 Iododeoxyuridine ( 131 IDU) was injected into normal and partially hepatectomized rats, and the specificity of incorporation of this thymidine analogue into liver DNA was determined 2, 24 and 48 hr following intramuscular injection. At 2 and 24 hr after 131 DU injection, a major proportion of radioactivity in the liver was in the acid‐soluble fraction, whereas 48 hr after injection the label in the acid‐soluble fraction had decreased considerably. In liver obtained 2 hr after injection of 131 IDU, only 1.8–16.6% of the total radioactivity were in DNA. If, however, the tissue was subjected to formalin fixation, the acid‐soluble label was extracted selectively, and of the remaining radioactivity 64–88% was in DNA. Therefore, the radioactivity that is not extracted by formalin may be used as a measure of DNA synthesis at the time of injection of 131 IDU, thus obviating time‐consuming biochemical fractionation procedures.