FACTORS ALTERING CONCENTRATION OF BLOOD LIPIDS 



475 



blood lipoprotein which is combined with cholesterol may offer a fairly 

 constant relationship. Thus, it was shown that, in the human subject, in 

 addition to S f 3-8 molecules, varying quantities of a fraction described as 



a, human 



rabbit 



Fig. 7. Ultracentrifugal flotation diagrams of lipids and liproproteins in human 

 and rabbit sera: 96 (a) normal human serum showing only S f 3-8 class; (b) human 

 serum showing moderate amount of S f 10-20 class; (c) human serum showing 

 high concentration of S f 10-20 class; (a') normal rabbit serum showing only a 

 lipoprotein of S f 5-8 class; (b') rabbit serum from animal shortly after start of 

 cholesterol feeding, showing small amount of S f 10-30 class with S f 5-8 fraction; 

 (c') rabbit serum from animal after extended period of cholesterol feeding (this 

 has a large amount of S f 10-30 fraction and also lipoproteins of S f 5-8 class). 

 The analytical runs were made at a rotor speed of 52,640 r.p.m. in a cell of 0.8 

 ml. capacity. 



