636 



ADVENTURES IN RADIOISOTOPE RESEARCH 



The liver of our rats contained 10 ^gm of nuclear haemin iron out of 

 2.5 mgm of total iron present in the liver. This fraction makes out 0.4% 

 of its total iron content. 



In the course of the purification process in aqueous medium extract- 

 able haemoglobin may have been removed. However, the non-extractable 

 haemoglobin content of the nuclei was not found to be larger when the 

 nuclei were isolated after lyophilisation in organic medium. In the haemo- 

 globin content of the nuclear fraction of the red cells of the hen when 



200- 



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 o 



SI 



o 



£:-i20- 



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o 80- 



CO 



40- 



■ 



B 



1 



C 



I 



■ 



D 



m 



Fractions of particles with increosing specific gravity and size 



Fig. 1. Results of separation of nuclear components of the liver 

 cells of the rat in Lindahl's counter-streaming centrifuge. 



A — Total nuclear fraction, prepared according to Hogeboom. 



B — Impure mitochondria containing erythrocytes. 



C — Erythrocytes and small fibres of connective tissue. 



D — Cell membranes. 



E — SmaU nuclei. 



F — Large nuclei. 



these were isolated in an organic medium, Stern etalM"^^ found a haemo- 

 globin-iron content of 19% of that of the total red corpuscle, while 

 we find after isolation of the nuclei in an aqueous medium 1% of the 

 total haemoglobin-iron content to be non-extractable. This 1% compares 

 with 0.4% found by us in the liver nuclei of rats and 2% in those of the 

 rabbit. 



We compared also the effect of irradiation with 500 r of X-rays on 

 rats on the incorporation of ^^Fe into the liver nuclear haemoglobin 

 fraction. As seen in Table 1 the X-ray effect is shortly after exposure a 

 very restricted one for both haemoglobin fractions. The X-ray effect 

 as seen in Fig. 2 doesn't seem as pronounced as that on the circulating 

 haemoglobin. If we, however, take into account the enhanced activity 

 of the liver of the exposed animal, this difference is strongly reduced. 



