ACETIC ACID AND ACETATE 269 



evidence points to the fact that the source of the carbohydrate, in this 

 case, is the glycerol of the triacetin molecule and not the acetic acid moiety. 

 Moreover, when acetic acid is fed to fasting rats, it provokes ketonuria, 

 and does not act as a source of ketolytic material. ^^^'^^^ Further evidence 

 that the course of metabolism of glucose is quite independent of that of 

 acetate is obtained from the experiments of Drury and Wick."^ Although 

 the presence of acetate was found to reduce the rate of oxidation (but not 

 of disappearance) of glucose in the insulin-treated, eviscerated rabbit, these 

 factors did not influence the rate of oxidation of the acetate. This is 

 interpreted to mean that neither acetate nor any of its derivatives forms 

 a pool with any derivative of glucose. 



(h) The Effect on the Composition of Glycogen. It has been demonstrated 

 by Buchanan and Hastuigs^" and by Wood""* that radioactive carbon from 

 labeled acetate becomes incorporated into glycogen after the test material 

 has been fed. In fact, Lorber, Lifson, and Wood^^^ demonstrated that 

 radioactive carbon was present in all six carbons of glucose. However, 

 it was found that acetic acid cannot form glycogen spontaneously, ^^^ 

 but only as a result of becoming incorporated in the tricarboxylic acid 

 cycle. Under such conditions, it yields pyruvate, which is an obligatory 

 intermediate in glucose synthesis. ^'^^^ Strisower et aZ.^^^ reported that 

 liver slices from normal rats were able to change acetate-1-C^^ to glucose 

 to the extent of 3 to 6%, while acetate-2-C'^ was transformed to carbo- 

 hydrate to the extent of 10 to 19%. The extent of incorporation of C'^ 

 into glucose was somewhat augmented in Liver shces from diabetic animals; 

 on the other hand, the incorporation of acetate into glucose was greatly 

 reduced by insulin. The C^^Oa production was two to three times as 

 great with carboxyl-labeled acetate as it was in the case of the methyl- 

 tagged acid. The variations in CO2 production were not great between 

 normal and diabetic liver slices, but the C^"*02 recovery from both substrates 

 was reduced by 50% in the hvers from the insulin-treated diabetic rats. 



b. Fatty Acid S5mthesis. Acetic acid is the building stone for both fatty 



1" E. M. MacKav, R- H. Barnes, H. O. Carne, and A. N. Wick, J. Biol. Chem., 185, 

 157-163(1940). 



1'^ M. E. Swendseid, R. H. Barnes, A. Hemingway, and A. O. Nier, J. Biol. Chem., 

 ^4^,47-52(1942). 



i^« D. R. Drury and A. N. Wick, J. Biol. Chem., 203, 411-417 (1953). 



1'^ J. M. Buchanan and A. B. Hastings, Physiol. Revs., 26, 120-155 (1946). 



"8 H. G. Wood, Physiol. Revs., 26, 198-246 (1946). 



n" V. Lorber, N. Lifson, and H. G. Wood, J. Biol. Chem., 161, 411-412 (1945). 



120 N. Lifson, V. Lorber, and H. G. Wood, Federation Proc, 4, 47 (1945). 



•2> E. H. Strisower, G. D. Kohler, and I. L. Chaikoff, J. Biol. Chem., 198, 115-126 

 (1952). 



