788 VII. LIPID DISTRIBUTION IN SPECIFIC TISSUES 



1.34% (recalculated), and sphingomyelin in the amount of 1.46% (re- 

 calculated). In later studies, Thannhauser and his collaborators 444 iso- 

 lated hydrolecithin as a component of lung phospholipids. It was identi- 

 fied as a dipalmityl lecithin. The amount of hydrolecithin present in the 

 lung tissue varied between 20 and 40% of the sphingomyelin content of 

 this organ. 



The fluid isolated from the respiratory tract of the rabbit, cat, and dog- 

 was shown by Boyd et a/. 445 to contain all the lipids present in the blood, 

 but in smaller amounts. Table 24 summarizes these data (page 787). 



11. Lipids Present in the Pancreas 



Pancreas differs from other glandular tissues in having a considerably 

 higher content of neutral fat (acetone-soluble fraction), in relation to the 

 other lipid components. Thus, Bloor 23 reported that fresh beef pancreas 

 had the following composition: lecithin, 1.05%; cephalin, 0.82%; ace- 

 tone-soluble fraction, 3.90%; and unsaponifiable residue, 1.29%. 



In addition to the usual tissue lipids, a number of partial hydrolysis prod- 

 ucts of the phospholipids have been prepared from pancreatic tissue. 

 Klenk and Friedrichs 40 reported that plasmalogens comprised 4% of the 

 total phospholipids in swine pancreas. Jones and co-workers 26 demon- 

 strated the presence of monopalmitin in hog pancreas, in amounts of 1.7 

 to 1.9% of the fresh tissue weight. Glycerophosphorylcholine (choline 

 glycerophosphate) is another component of pancreatic tissue. This com- 

 pound originates by the splitting of two fatty acid residues from lecithin, 

 which may be accomplished by the action of lecithinase B on lecithin. 

 Schmidt et aZ. 446 and King and Aloisi 447 reported the presence of glycero- 

 phosphorylcholine in beef pancreas. Both the a- and the /3- forms of this 

 compound have been isolated from pancreas. 447 ' 448 



King and Small 449 isolated an intermediate of sphingomyelin from 

 pancreas which is believed to be sphingosine choline phosphoric ester. 

 This is the compound formed after the fatty acid residue has been removed. 



444 S. J. Thannhauser, J. Benotti, and N. F. Boncoddo, /. Biol. Chem., 166, 669-675 

 (1946). 



445 E. M. Boyd, S. Jackson, M. MacLachlan, B. Palmer, M. Stevens, and J. Whit- 

 taker, J. Biol. Chem., 153, 435-438 (1944). 



446 G. Schmidt, B. Hershman, and S. J. Thannhauser, /. Biol. Chem., 161, 523-536 

 (1945). 



447 E. J. King and M. Aloisi, Biochem. J., 39, 470-473 (1945). 



448 M. Aloisi and P. Buffa, Biochem. J., 43, 157-160 (1948). 



449 E. J. King and C. W. Small, Biochem. J., 33, 1135-1139 (1939). 



