Originally published in Experientia 7, 144 (H).51) 



39. TURNOVER RATE OF THE FATTY ACIDS OF 



THE LIVER 



G. Hevesy, R. Ruyssen and M. L. Beckmans 



From the Pharmaceutical Institute of the University of Gent and Institute 



for Research in Organic Chemistry, Stockholm 



The rate of renewal of the fatty acids of the hver and other organs has 

 been repeatedly determined by making use ol' deuterium, carbon 

 13 and carbon 14 as an indicator. In early experiments Schoenheimer 

 and RiTTENBERG^i) administered heavy water to mice and kept the 

 deuterium content of body fluids at a constant level throughout the 

 experiment. The saturated fatty acids of the mouse reached half of their 

 maximal deuterium content in the time of 5 to 9 days. The deuterium 

 content of the saturated acids was higher than that of the unsaturated. 



Bernhard and Schoenheimer<2> isolated the fatty acids of the 

 intestinal wall, the kidneys and the liver of the mouse and found the 

 saturated fatty acids to have an appreciably higher deuterium^^) content 

 than had that of the unsaturated ones. They estimate the half-life time 

 of the average saturated fatty acid molecule in the liver of the mouse 

 to be al)out 1 day, while the half-life time of the total fatty acids in the 

 rat liver was found by Stetten and Boxer^^) to be 1.9 days. 



The finding of Rittenberg and Bloch<^> that the feeding to mice of 

 acetate containing ^^C " in the carboxyl group leads to the formation of 

 fatty acids containing ^^Q, opened the way to the application of i^C 

 and i^C in the study of the rate of formation of fatty acids. They found 

 a more rapid incorporation of ^^C in to the saturated than into the 

 fatty acids. The i^C concentration of the carboxyl carbon atoms of the 

 saturated fatty acids was approximately twice as high as the average of 

 all the carbon in the saturated fatty acids. The most plausible distribu- 

 tion which will explain these data is one in which the labelled carbon is 



(1^ R. Schoenheimer and D. Rittenberg, J. Biol. Chem. 114, 381 (lOSG). 

 D. Rittenberg and R. Schoenheimer, J. Biol. Chem. 114, 381 (1936). 



(-^ K. Bernhard and R. Schoenheimer, J. Biol. Chem. 133, 713 (1940). 



(3) K. Bernhard and F. Bullet, Helv. chim. Acta 26, 75, 1185 (1943). 



(*)D. Stetten Jr., and G. E. Boxer, J. Biol. Chem. 155, 231 (1944). 



(5)D. RiTTENBERGand K. Bloch, J. Biol. Chem. 154, 311 (1944). K. Bloch 

 and D. Rittenberg, J. Biol. Chem. 159, 45 (1945). D. Rittenberg and K. Bloch, 

 J. Biol. Chem. 160, 417 (1945). 



26* 



