Incorporation DU [1,5-14C2]citrate dans les differents acides gras de la souris vivante

Abstract [1,5- 14 C 2 ]Citrate or [4- 14 C]aspartate together with [2- 3 H]acetate were applied to mice intravenously or by intubation. The incorporation of these precursors into fatty acids of the liver, carcass, intestine and kidney was studied at different time intervals after the administration. The radioactivity of fatty acids present in liver subcellular fractions was also measured. [1,5- 14 C 2 C 2 ]Citrate was incorporated into fatty acids of carcass and liver to a much lesser extent than [2- 3 H]acetate. Moreover, it was found that in contrast with [2- 3 H]acetate the radioactivity of [1,5- 14 C 2 ] citrate and [4- 14 C]aspartate appeared predominantly in the stearic acid. The experiments with liver tissue fractions revealed that [1,5- 14 C 2 ]citrate and [2- 3 H] acetate were incorporated into fatty acids of microsomes and of supernatant in the same proportion whereas in mitochondrial fraction the acetate incorporation predominated. From the time-course experiments it may be concluded that the 3 H/ 14 C ratio found in liver, adipose and muscle tissues after the administration of [2- 3 H]- acetate as well as [1,5- 14 C 2 ]citrate increased as a function of time. These results are discussed in relation to the role of citrate in the regulation of fatty acid synthesis.