The Rôle of the Liver in the Synthesis of Fatty Acids from Carbohydrate *

Little is known about the chemical reactions involved in the conversion of carbohydrate to fatty acids. Hypothetical schemes have been abundant, and have included aldol condensation of acetaldehyde (Magnus-Levy2"), aldol condensation of acetaldehyde with pyruvic acid (Smedley,30 Smedley and Lubrzynska81), direct condensation of hexoses (Fischer1"), and other possibilities (Hilditch15). The lack of experimental data upon which a rational synthetic scheme might be constructed is not surprising in view of the prevailing uncertainty concerning the very site of the reaction. The studies of Hoffmann and Wertheimer,"6 Hausberger and Neuenschwander-Lemmer,"3 Ruska and Oestreicher,29 Henle and Szpingier,"4 and, more recently, those of Tuerkischer and Wertheimer3" and of Mirski25 have clearly established the fact that, at least in some circumstances, adipose tissue itself is capable of converting carbohydrate to fatty acids. The work of Henle and Szpingier and of Mirski is especially noteworthy, for these investigators devised in vitro systems for the study of the reaction. The evidence in support of hepatic synthesis of new fat can be considered only presumptive, although some authorities (Longenecker22 and Hilditch15) believe the liver tissue to be capable of effecting the conversion. This view is shared by Gavin and McHenry,"1 who found large concentrations of fatty acids in the livers of rats which were synthesizing fatty acids from carbohydrate. In addition, Waelsch and his co-workerse7 analyzed the livers of animals which were given a high-carbohydrate diet and deuterium oxide in their drinking water and found high concentrations of deuterium-containing (i.e., newly synthesized) fatty acids. However, these chronic experiments on intact animals do not constitute