78 III. OXIDATION AND METABOLISM 



acids containing four or more carbons produce an exogenous ketonuria 

 when fed to fasting rats, the odd-carbon acids give rise to none, or to Umited 

 quantities of ketone bodies. Thus, Deuel and co-workers" reported no 

 ketonuria after the administration of ethyl propionate or the ethyl esters 

 of valeric, heptanoic, or nonanoic (pelargonic) acids. However, a slight 

 ketonuria was noted after the sodium salts of valeric or heptanoic acids were 

 fed.^^ MacKay and co-workers-^ reported that the odd-chain fatty acids 

 having more than three carbons do give rise to limited amounts of acetone 

 bodies in rabbits, as evidenced by an increased level of blood ketones. 

 The formation of the ketone bodies is attributed to the condensation of the 

 acetic acid molecules which are formed by rupture of two-carbon frag- 

 ments from odd-chain acids containing five or more carbons. 



Another marked difference in the behavior of odd- and even-carbon acids 

 is their relation to carbohydrate formation. No glycogen production 

 could be observed when the ethyl esters of butyric, caproic, caprylic, 

 capric, lauric, myristic, or oleic acid were fed to rats,^^ nor when the 

 sodium salts of diacetic, butyric, caproic, or caprylic acid were admin- 

 istered.-^ On the other hand, there is ample evidence that the odd-chain 

 fatty acids give rise to glycogen. Ringer" reported, in 1912, that propionic 

 acid resulted in "extra" sugar in the phlorhizinized dog; moreover, it was 

 later showTi that the administration of valeric and heptanoic acids likewise 

 resulted in glucose formation, to the extent of three carbons in each mole- 

 cule. ^^ An increase in blood sugar in rabbits was noted by Pollak^^ after 

 the intravenous injection of the salts of propionic and valeric acids, but 

 not following the administration of salts of acetic, butyric, acetoacetic, or 

 caproic acids. In addition, Deuel and collaborators reported that pro- 

 pionic, valeric, heptanoic, and nonanoic acid gave rise to definite amounts 

 of liver glycogen when fed to fasting rats as their sodium salts,-® or as their 

 ethyl esters.-^ MacKay et al.^"^ likewise found that propionic acid pro- 

 duced glycogen when fed to fasting rabbits. Atchley,^" employing the 

 newly-developed technic involving countercurrent distribution, was able 

 to separate propionic acid, rather than butyric acid, when valeric acid was 



" E. M. MacKay, A. N. Wick, and C. P. Barnum, /. Biol. Chem., 136, 503-507 

 (1940). 



25 J. S. Butts, H. Blunden, W. Goodwin, and H. J. Deuel, Jr., J. Biol. Chem., 117, 

 131-133 (1937). 



26 H. J. Deuel, Jr., J. S. Butts, L. F. Hallman, and C. H. Cutler, /. Biol. Chem., 112, 

 15-23 (1935-1936). 



27 A. I. Ringer, J. Biol. Chem., 12, 511-515 (1912). 



28 A. I. Ringer, J. Biol. Chem., U, 43-52 (1913). 



29 L. Pollak, Biochem. Z., 127, 120-136 (1922). 



30 W. A. Atchley, /. Biol. Chem., 176, 123-131 (1948). 



