CHANGES IN LIPIDS OF CELLULAR MICROSTRUCTURES 



145 



bound state, mostly in the "loosely bound" form. The hyaloplasm re- 

 veals a rather different ])ieturc: about 40 per cent of its lipids are in the 

 "free" state, and the bound lipids are found in the "firmly bound" 

 fraction (Figs. 1 and 2). 



5 



1) -o 



■^ EL 

 D .9- 



a. 



60 



50- 



40 



30 



20 



10 



— -I 



/" 



11 



'IV 



Normal 24 



Hours after irradiation 



72 



Fig. 2. — The content (percentage of drj' weight) of various hpid fractions in the liyalo- 

 plasm of rabbit Uver cells under conditions of acute radiation disease ; curves as in Fig. 1. 



Twenty-four hours after irradiation (in accordance with the investi- 

 gations carried out earlier) an increase in the total lipid content was 

 found especially in the mitochondria and microsomes (Table I). In the 

 hyaloplasm these increases were a consequence of an increase in the 

 bound (mostly "firmly bound") lipids; the portion of the "free" 

 lipids decreased (up to 30 per cent). In the organelles an even greater 

 increase in the content of bound lijsids occm^red with a pronounced 

 tendency to the accumulation of "loosely bound" lipids. It should be 

 noted that a small (in terms of absolute values), but relatively sub- 

 stantial increase of the "free" lipids up to values surpassing the normal 

 by ten-fold (up to 2 per cent of the total lipid content) was observed. 



Seventy -two hours later the ensuing decrease of the total lipids to an 

 apparently almost normal value was accompanied by further dis- 

 turbances in the ratio between the different lipid fractions. The hyalo- 

 plasm showed a considerable reduction of the bound fractions along 

 with an increase of the content of "free" lipids; such a situation led to 

 a certain normalizing of the relations between the lipid fractions. At 

 this ])oint the content of bound lipids in the cytoplasmic organelles 

 dropped below the normal values; and the "firmly bound" fraction 

 was particularly lower in this case. The content of the "free" lipids in 

 cytoplasmic organelles kept increasing and exceeded the normal values 



