INFLUENCE OF RADIATION ON METABOLISM OF 

 REGENERATING RAT LIVER 



Barbara E. Holmes 



Department of Radiotherapeutics , University of Cambridge 



Any attempt to discover something of the biochemical 

 reactions concerned in cell division or the effects of irradiation 

 on the mitotic processes, is liable to lead to the necessity of 

 dealing with single cells or cells dividing synchronously. The 

 use of growing tissues is limited by the fact that all stages of 

 the mitotic cycle are here present together and any estimation 

 can only give an average value. Histochemical techniques 

 have been evolved to make possible the examination of a 

 single cell and the elegant autoradiographic methods of Pelc 

 and Howard are among the most successful. For work on a 

 larger scale the synchronously dividing tissue is useful and, 

 among mammalian tissues, the regenerating liver is a con- 

 venient example. 



Price and Laird (1953) and also Abercrombie and Harkness 

 (1951), Stowell (1949) and others who introduced the experi- 

 mental use of regenerating liver tissue, found that a large 

 synthesis of DNA had taken place in the remaining lobes of a 

 rat liver 24 hours after hepatectomy, whereas cell division 

 had not yet begun. An opportunity of studying the chemical 

 events leading up to mitosis was thus available. This tissue 

 was used in our laboratory to examine the radiosensitivity of 

 different stages of the mitotic cycle. Mrs. Kelly of the Donner 

 Laboratory used carbon tetrachloride poisoning to cause 

 partial destruction of liver cells, which was followed by 

 regeneration, and estimated the effect of whole body irradi- 

 ation on this. She found a very large increase in DNA synthesis 

 in the liver, beginning at 30 hours, and reaching its peak at 

 36 hours after administration of the drug; a high rate of 



RAD. 225 9 



