TRIGLYCERIDES AND FATTY ACIDS 81 



caproic acids break down by |Q-oxidation, the even-chain carbon acids con- 

 taining eight to fourteen carbon atoms are probably also broken down by 

 5 and f-oxidation by a procedure of "multiple alternate oxidation." The 

 data obtained from in vivo tests thus support the in vitro experiments of 

 Jowett and Quastel. 



The results of oxygen consumption tests on perfused livers and on liver 

 slices have offered support for the hypothesis that long-chain fatty acids 

 yield more ketone bodies per molecule than do the short-chain acids. 

 Thus, Blixenkrone-M0ller^'' reported that the ratio of oxygen consumption 

 of the perfused livers of diabetic cats to ketone body production was such 

 as to indicate that four ketone body molecules were formed from each 

 fatty acid molecule oxidized, rather than that a more complete oxidation 

 occurred, with the production of two carbon residues such as in acetic acid. 

 Likewise, Stadie^^ reported that the ratio of O2 consumption to ketone pro- 

 duction in liver slices of the diabetic cat was such as to preclude successive 

 iS-oxidation as the explanation for the fatty acid oxidation in liver. These 

 calculations are summarized in Table 1. 



The quantitative aspects of acetoacetate formation from long-chain fatty 

 acids have recently been supported by an m vitro system. Thus, Witter, 

 Cottone, and Stotz^^ reported that, when fatty acids ranging in length from 

 C2 to Ci7 were oxidized by particulate preparations from rat liver and by 

 mitochondria, all acids were vigorously oxidized except acetic and pro- 

 pionic. The fatty acids with an even number of carbon atoms were 

 changed quantitatively to ketone bodies. In the case of the odd-chain 

 acids, the yield of acetoacetate was slightly in excess of one mole of aceto- 

 acetate for each mole oxidized. 



Stadie" suggests that the principal experimental fact which argues 

 against the successive /S-oxidation theory, and which might thus be con- 

 sidered to support the multiple alternate oxidation theory, is the failure 

 to detect acetic acid*^"^* or any of the hypothetical intermediate acids hav- 

 ing less than twelve carbon atoms, in the tissues or depot fats.*^ Thus, 

 Stadie et al.,*'^ employing a procedure which was capable of detecting ex- 

 tremely small amounts of acetic acid, were unable to detect traces of this 

 compound in li^-er slices producing large quantities of ketone bodies. 



« N. BlLxenkrone-M0ller, Z. physiol. Chem., 252, 117-136 (1938). 

 ^1 W. C. Stadie, Harvey Lectures, 37, 129-167 (1942). 



« G. Embden and L. Michaud, Beitr. chem. Physiol. Pathol., 11, 332-347 (1908). 

 " E. Toenniessen and E. Brinkman, Z. physiol. Chem., 252, 169-195 (1938). 

 " W. C. Stadie, J. A. Zapp, Jr., and F. D. W. Lukens, /. Biol. Chem., 137, 75-87 

 (1941). 



** D. L. Cramer and J. B. Brown, J. Biol. Chem., 161, 427-438 (1943). 



