868 



ADVENTURES IX RADIOISOTOPE RESEARCH 



other b}^ the fact that the physiological death rate of the mammalian 

 red corpuscle not containing DNA may be accelerated by exposure of 

 the organism to radiation. Irradiation reduces their life-cycle possibly 

 partly through production of agencies promoting haemolysis. 



Interference with the rate of blood flow is another example where 

 processes independent from cell division promote cell death. Dobs on 



1000 



o 



c 



Q. 



10 



o 



c 

 o. 



u 



£ 

 o 



I- 

 x: 

 o 



100 



c 

 o 



c 

 « 

 o 

 c 

 o 

 u 



TD 

 O 

 O 



> 



Cf. 



5 



After irradiotion 



( 1,9 "10^ ergs/gram livertissue 

 " 2300 rep) ' 



^*- 



Before liver irradiaton 



15 30 45 



Time in minutes 



60 



Fig. 11. Changes in the rate of chronic phosphate disappearance 

 with liver irradiation in the rabbit. 



and Jones (1951) followed the rate of disappearance of colloidal chromic 

 phosphate labelled with ^^P from the circulation of various animals and 

 found it markedly depressed after exposure to 2300 r (cf. Fig. 11). 

 The depression observed is at least partly due to a diminution of the 

 rate of liver blood flow. 



That it is a cytological damage which is responsible for the interference 

 with haemoglobin formation was shown by making use of the autoradio- 

 graphic technique, thus applying a direct method by Lajtha and Suit 

 (1955) and Suit, Lajtha and Oliver (1956). They studied incorporation 

 of ^^Fe into both irradiated and non-irradiated human bone-marrow cells 

 in vitro, and into bone marrow of the rabbit in vivo. The application of 

 the autoradiographic method led, as was mentioned on page 859, in the 

 hands of Howard and Pelc to very important results. Striking results 

 were also obtained by Lajtha and Suit. They could demonstrate very 

 convincingly that although the early cell forms of the nucleated red 



