LIPIDS PRESENT IN LIVER 709 



several lipids, the liver plays a commanding role in the metabolism of 

 carbohydrate 19 - 20 and of protein. 21 



(1) The Lipid Composition of Normal Liver 



The liver of man and of most mammals contains 3 to 5% of total lipids. 

 Theis 22 reported that the lipids of beef liver comprised 4.6% of the total 

 weight of the organ ; of this, 55% consisted of phospholipids and 45% of ace- 

 tone-soluble components (neutral fat, cholesterol, etc.). On the other hand, 

 Bloor 23 reported a figure of 4.2% for the total lipid content of beef liver, 

 73% being classified as phospholipids and the remaining 27% as the ace- 

 tone-soluble portion. Deuel et al. 2i recorded values for total liver lipid 

 between 3.5 and 4.0% for normal rats on stock diet. Sperm whale liver 

 lipid was shown by Tsujimoto and Kimura 25 to comprise about 6% of the 

 total weight of the organ, of which 69.3% was fatty acid and 16.4% was 

 non-saponifiable. Jones et aZ. 26 found that the liver, unlike the pancreas, 

 contains only traces of a-monoglycerides. 



a. Fatty Acids Present in the Liver. The outstanding discovery in the 

 investigation of the liver fatty acids was the demonstration by Hartley 27 - 28 

 that arachidonic acid occurs, as well as a 12,13-octadecenoic acid. The 

 presence of the latter acid could not be confirmed by Channon and col- 

 laborators. 29 The mean molecular weight of the fatty acids in liver re- 

 ported by Hartley 28 was 308 to 312, compared with a theoretical value of 

 282 for oleic acid. According to Brown, 30 arachidonic acid is the only 

 highly unsaturated acid present ; it comprises 2 to 7.7% of the total fatty 

 acids in the liver. In the case of rats, Wesson 31 reported that the adminis- 

 tration of cod-liver oil increased the arachidonic acid four-fold; this in- 

 crease occurred primarily in the liver. A C 2 2-unsaturated acid has been 



19 F. C. Mann and T. B. Magath, Am. J. Physiol, 55, P 285-P 286 (1921). 



20 F. C. Mann and T. B. Magath, Arch. Internal Med., 30, 73-84 (1922). 



21 F. C. Mann and T. B. Magath, Am. J. Physiol, 55, P 286-P 287 (1921). 



22 E. R. Theis, /. Biol Chem., 76, 107-114 (1928). 



23 W. R. Bloor, J. Biol. Chem., 80, 443-459 (1928). 



24 H. J. Deuel, Jr., L. F. Hallman, and S. Murray, /. Biol Chem., 119, 257-268 

 (1937). 



26 M. Tsujimoto and K. Kimura, Chem. Umschau Fette, Ole, Wachse, u. Harze, 35, 

 317-318 (1928); Chem. Absl, 23, 723 (1929). 



26 M. E. Jones, F. C. Koch, A. E. Heath, and P. L. Munson, J. Biol. Chem., 181, 755- 

 760 (1949). 



27 P. Hartley, /. Physiol, 36, 17-26 (1907). 



28 P. Hartley, /. Physiol, 88, 353-374 (1909). 



29 H. J. Channon, E. Irving, and J. A. B. Smith, Biochem. J., 28, 1807-1811 (1934). 



30 J. B. Brown, J. Biol Chem., 80, 455-460 (1928). 



31 L. G. Wesson, /. Biol Chem., 65, 235-250 (1925). 



