QUANTITATIVE RELATIONS OF BLOOD LIPIDS 381 



{2) Normal Values of Blood Lipids in Various Animal Species 



Wide variations in the relative proportions and in the total lipids have 

 been observed in a number of species of animals examined. Table 5 lists 

 the normal fasting values of the lipids in a series of animals, as determined 

 by Boyd. 193 Abderhalden, 194 also reported the distribution of the lipids 

 between the plasma and the cells in a number of different species. These 

 results are recorded in Table 6. 



(3) The Lipid Components in Blood Cells 



a. Lipids in Erythrocytes. It is evident from the analyses of Abder- 

 halden 194 that the concentration of several of the lipid components in the 

 cells differs widely from their values in the plasma or serum. No appre- 

 ciable quantities of neutral fat occur in the red blood corpuscles; in fact, 

 the quantities are so small that Abderhalden 194 was unable to assign a value 

 to them. If one calculates the concentration of total lipids in serum, from 

 the data in Table 6, on the basis that all that appears in whole blood is 

 present in the serum fraction, the calculated and observed values are quite 

 close. In three cases, the calculated figures are lower than the observed 

 values, while in five instances they are higher. The average deviation of 

 the calculated from the observed values is 7.25%. 



The calculations for serum fat based upon the known determination in 

 whole blood are made as follows : 



1000 g. of whole blood occupies 948 ml. (1000: 1.055 (specific gravity)). 



1000 g. of serum occupies 973 ml. (1000: 1.027 (specific gravity)). 



948 ml. of whole blood (1000 g.) contain 568 ml. serum. Plasma is 60% of the volume 



of whole blood. 

 Fat in 1000 g. of serum (973 ml.) will be (973:568) X concentration in 1000 g. whole 



blood. (This assumes that neutral fat is exclusively in the serum.) 



Although neutral fat is practically completely absent from the erythro- 

 cytes, fatty acids occur in combination with phospholipids, and to some 

 extent with cholesterol. In addition, Erickson and her associates 78 demon- 

 strated that some of the cell fatty acids are combined in the cerebroside 

 molecule ; the erythrocytes contain 47 milligrams per cent of the latter. 



According to Bloor, 195 ' 196 blood cells contain 400 to 440 mg. of phospholi- 

 pid per 100 ml., which is about double the concentration in plasma. The 



193 E. M. Boyd, /. Biol. Chem., 143, 131-132 (1942). 



194 E. Abderhalden, Physiological Chemistry, translated by W. T. Hall and G. Defren, 

 Wiley, New York, 1908. 



195 W. R. Bloor, J. Biol. Chem., 22, 133-144 (1915). 



196 W. R. Bloor, /. Biol. Chem., 26, 417-430 (1916). 



