710 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



detected by Klenk and von Schoenebeck 32 in beef liver fat. Hilditch and 

 Shorland 33 likewise noted the presence of C20- and C 2 2-unsatu rated acids in 

 the liver fat of New Zealand cattle. Except for these unsaturated acids 

 and a hexadecenoic acid, the liver fat and the depot fat were similar. 

 A still more unsaturated acid, clupanodonic acid, has been demonstrated 

 in fat from the European brown frog (Rana ternporaria). Si Presumably it 

 is present largely in the liver. 



The percentages of the fatty acids in terms of the total mixed fatty acids 

 in pig liver were found to be the following 35 : n-decanoic and lauric (C12), 

 0.4%; myristic (C 14 ), 0.7%; palmitic (Ci 6 ), 14.0; stearic (C 18 ), 18.8%; 

 arachidic (C 2 o), 1.7%; palmitoleic (G 6 ), 1.5%; oleic (Cw), 28%; linoleic 

 (Cis), 5%; C 2 o-acid, 20%; and C 2 2-acid, 7.5%. These figures compare 

 with those of Klenk and von Schoenebeck 32 for solid acids in beef liver, 

 which were cited as follows: C14, trace; Ci 6 , 25%; Cis, 20%; C 2 o, trace; 

 C22, trace. For liquid acids the values were: Cm, trace; C16, 9%; Cis, 

 37%; C 20 ,8%; and C 22 , 1%. 



b. Phospholipids in the Liver. The total phospholipids in the livers of 

 a large number of animals range from 1.5 to 3.7% of the net weight of the 

 organ. Lecithin and cephalin occur in about the same proportion. Sphin- 

 gomyelin has been shown to comprise less than 5% of the total phospho- 

 lipids in human liver tissue (0.38% for sphingomyelin compared with 

 9.80% for total phospholipids, based upon dry weight), 36 while Schmidt 

 et al. 37 recorded a value for sphingomyelin of 2.6% of the total phospholipids 

 in rat liver. 



The presence of glycerophosphoric acid in the liver has been suggested 

 by the results of Cahn and collaborators. 38 These workers indicate that 

 part of the phosphoric acid is in the form of glycerophosphoric acid, rather 

 than of the more complicated phospholipids; they base their conclusion 

 upon the fact that the total amount of fatty acid is insufficient for the phos- 

 pholipids, calculated from the amount of their other constituents. 



Glycerylphosphorylcholine, also, has been shown to be present in animal 

 tissues. Thus, after developing a method for its quantitative determina- 



32 E. Klenk and O. von Schoenebeck, Z. physiol. Chem., 209, 112-133 (1932). 



33 T. P. Hilditch and F. B. Shorland, Biochem. J., 31, 1499-1515 (1937). 



34 E. Klenk, Z. physiol. Chem., 221, 259-264, 264-270 (1933). 



36 E. Irving and J. A. B. Smith, Biochem. J., 29, 1358-1368 (1935). 



36 S. J. Thannhauser, J. Benotti, A. Walcott, and H. Reinstein, J. Biol. Chem., 129, 

 717-719 (1939). 



37 G. Schmidt, J. Benotti, B. Hershman, and S. J. Thannhauser, /. Biol. Chem., 166, 

 505-511(1946). 



38 T. Cahn, J. Houget, and R. Agid, Bull. soc. chim. biol, 31, 766-778 (1949). 



