QUANTITATIVE RELATIONS OF BLOOD LIPIDS 387 



tendency- to maintain a fair degree of constancy in the ratios between cer- 

 tain lipids. A number of different interrelationships have been postulated, 

 but only a few of these appear to be of sufficient uniformity to be of any 

 considerable importance. 



a. Lipemic Constant. The lipemic constant (or coefficient) is the value 

 expressed by the ratio of blood cholesterol : blood fatty acids. The uniformity 

 of this ratio for each species was first recognized by Mayer and Schaeffer 206 

 in 1913. Terroine 207 reported that the relationship between cholesterol and 

 fat in the blood is maintained during the absorption of fat, both values 

 rising simultaneously. In later experiments of this worker, 208 it was shown 

 that the ratio (blood cholesterol -.blood fatty acids) X 100 averaged 36 in 

 fourteen dogs, with a range of 23 to 50, and with an average variation of 

 only 17%. According to Bloor, 7 other workers have not always supported 

 Terroine, although it seems to be generally agreed that fatty acids and chole- 

 sterol both increase during fat absorption. Among others, Bang 209 has 

 indicated that the fat : cholesterol ratio is relatively constant. 



b. Lipemic Index. The lipemic index is simply the total lipid content 

 of the blood. Under normal conditions, this value remains quite constant. 

 Terroine 207 postulated that, since the lipemic index and the lipemic constant 

 are relatively uniform for any one animal, the combined values furnish a 

 means for identifying any single specific individual. 



c. Cholesterol : Lipid Phosphorus Ratio. The most important inter- 

 relationship appears to be that which exists between the cholesterol and 

 the phosphatide fraction in the blood. Bloor 210 was the first to report that 

 the cholesterol : lecithin ratio in human blood is constant, both under normal 

 and under pathological conditions. Horiuchi 211 also noted a uniformity of 

 this proportion in rabbits, while Grigaut and Yovanovitch 212 were likewise 

 able to maintain a constant relationship between these components under 

 a wide variety of circumstances. Neutral fat was shown to have widely 

 different values, and to bear no constant relationship to the phospholipids. 



Since lecithin is the principal phospholipid in blood, it is understandable 

 that the cholesterol -.lipid phosphorus ratio would also be uniform. Peters 

 and Man 213 have made an extensive study of this latter proportion in a large 



206 A. Mayer and G. Schaeffer, J. physiol. path, gen., 15, 984-998 (1913). 



207 E. F. Terroine, /. phijsiol. path, gen., 16, 212-222 (1914). 



208 e. F. Terroine, Ann. Set. Nat. Zool. [10] 4, 5-397 (1920). 



209 I. Bang, Biochem. Z., 90, 383-387 (1918). 



210 W. R. Bloor, J. Biol. Chem., 25, 577-599 (1916). 



211 Y. Horiuchi, /. Biol. Chem., 44, 345-361 (1920). 



212 A. Grigaut and R. Yovanovitch, Compt. rend. soc. biol, 91, 1310-1313 (1924). 



213 J. P. Peters and E. B. Man, J. Clin. Invest., 22, 707-714 (1943). 



