196 III. OXIDATION AND METABOLISM 



dation of fat, Goldman, Chaikoff et al.^^° carried out tests on normal and 

 on liverless dogs which were receiving emulsified, carboxyl-labeled tri- 

 palmitin intravenously. Only about 40% as much triglyceride was 

 utilized by the hepatectomized dogs as by normal animals, in spite of the 

 fact that the plasma fatty acid levels were higher in the hepatectomized 

 dogs than in the normal controls. 



On the basis of observations by Lehninger^'^^ and by Chernick, Masoro, 

 and Chaikoff,^^^ Goldman et al.^^" postulate that the oxidation of higher 

 fatty acids must be a normal occurrence in muscle. Direct evidence of 

 this utilization has been presented by a number of workers. Wertheimer 

 and Ben-Tor^^2 demonstrated that the fatty acids of rat serum were broken 

 down when diaphragm was incubated in it. The oxidation of the serum 

 fatty acids was completely inhibited by glucose, pyruvic acid, and aceto- 

 acetate, but only partially by galactose, fructose, and acetate. Thus, a 

 competition exists between glucose and fatty acid oxidation in muscle. 

 Hansen and Rutter^^^ reported that octanoic acid stimulates the oxidation 

 in rate diaphragm. The isolated diaphragms from animals previously 

 maintained on a high-carbohydrate intake were found to remove more 

 octanoate from the medium than did similar tissues from animals previously 

 fed a fat diet, but both stimulated oxygen consumption. Geyer and 

 associates'^* also found that octanoic and pentanoic acids, as well as 

 palmitic acid, were oxidized at a normal rate by eviscerated rats when 

 calculations were based upon specific activity data. Merlini'^^ reported 

 that the saturated fatty acids from Ci to C? are oxidized by auricle, while 

 Pignalosa'^' noted an irregular oxidation of fatty acids and esters by the 

 crystalline lens of scorbutic guinea pigs. 



Oiie may conclude from these data that fats can be utilized by tissues 

 other than the liver. It is of interest to ascertain to what extent ketone 

 bodies participate in tliis oxidation, both from the standpoint of synthesis 

 in the tissues involved, and also as related to their oxidation in extra- 

 hepatic organs. 



(a) Extrahepatic Synthesis of Acetone Bodies. Although the liver is the 



«M D. S. Goldman, I. L. Chaikoff, W. O. Reinhardt, C. Entenman, and W. G. Daiiben, 

 /. Biol. Chem., 184, 719-726 (1950). 



«"S. S. Chernick, E. J. Masoro, and I. L. Chaikoff, Proc. Soc. Exptl. Biol. Med., 73, 

 348-352 (1950). 



«32 E. Wertheimer and V. Ben-Tor, Biochsm. J., 50, 573-576 (1952). 



"3 R. G. Hansen and W. J. Rutter, /. Biol. Chem., 195, 121-126 (1952). 



69* R. P. Geyer, W. R. WaddeU, J. Pendergast, and G. S. Yee, J. Biol. Chem., 190, 

 437^43 (1951). 



•595 D. Merlini, /. phijsiol. pathol. gin., 39, 499-504 (1949). 



"6 G. Pignalosa, Boll, oculist, 23, 243-256 (1944). 



