trigly('euii)p:.s and fatty acids 145 



higher degree of ketonuria exhibited by female rats as compared with male 

 rats,^*^^ animals of the former sex have usually been preferred when it is 

 desirable to produce a high level of ketonuria in the control group. The 

 output of ketone bodies is sufficiently high to make a collection of urine and 

 a determination of ketone bodies possible on a daily basis. From a single 

 animal, one may obtain several confirmatory results over the four or five 

 days during which the experiment is continued. For more exact quantita- 

 tive comparisons of the ketolytic action of different metaboUtes, it is pref- 

 erable to compare levels of acetonuria of a control group receiving only 

 the butyrate with that of another group receiving butyrate plus the metab- 

 olite under study. 



There are a number of indications that the ketonuria produced by the 

 administration of sodium butyrate is physiologic, and compares with fast- 

 ing ketonuria in man. In the first place, the sex difference in susceptibiHty 

 to ketonuria, first reported by Deuel and Gulick^^a in human subjects, has 

 been repeatedly observed in rats since this phenomenon was first reported 

 by Butts and Deuel.^^* Moreover, the greater ketolytic effect exhibited 

 by galactose over that by glucose, first demonstrated by Deuel, Gulick, 

 and Butts^^" in man, has also been shown to obtain in rats.^*^ Finally, 

 the fact that no ketonuria occurs when the ketogenic acid is administered 

 to normally-fed rats,^^^ as well as the fact that the level of ketone body 

 excretion is reduced in proportion to the amount of ketolytic material fed, 

 are indications of the physiologic nature of the ketosis. Because this type 

 of ketonuria is produced as a result of ketogenic material fed simultaneously 

 to the experimental animal, it has been referred to as "exogenous keto- 

 nuria."^^^ 



b'. Endogenous Ketonuria: When rats which have developed fatty 

 livers as a result of being placed on a low protein, choline-free diet are 

 fasted, a ketonuria of considerable magnitude occurs, in spite of the fact 

 that no exogenous ketogenic material is being given. ^^"^ This phenomenon 

 is in contradistinction to the situation in normal rats, in which no appreci- 

 able ketonuria obtains during fasting unless ketogenic acids are fed simul- 

 taneously. The type of ketonuria resulting when rats with fatty livers are 

 fasted is known as "endogenous ketonuria. "^^^ Endogenous ketonuria 

 is also to be considered a physiologic type of ketonuria. Thus, female 



387 J. S. Butts, /. Biol. Chem., 105, 87-96 (1934). 



388 J. S. Butts, The Comparative Ketolytic Action of Glucose, Galactose, and Lactose, 

 When Administered to Rats Suffering from an Artificial Ketosis, Thesis, Univ. Southern 

 California, Dept. Biochem. Nutrition, 1933. 



383 H. J. Deuel, Jr., L. F. Hallman, and S. Murray, /. Biol. Chem., 124, 385-393 (1938). 

 390 H. J. Deuel, Jr., L. F. Hallman, and S. IMurray, /. Biol. Chem., 119, 257-268 (1937). 



