LIPID STORAGE UNDER ABNORMAL CONDITIONS 693 



normal manner. Bile produced by rats having fatty livers was likewise 

 shown to be low in total lipid, as well as in cholesterol. 



c'. Ketonemia and Ketonuria: Although fat deposits occurring in 

 fatty livers are generally regarded as metabolically inactive, there is some 

 evidence that they may stimulate fat oxidation. This deduction is based 

 upon the fact that the level of starvation ketonuria is markedly increased 

 in animals having fatty livers. 277 ' 904 Since ketogenesis has been shown to 

 be almost exclusively a function of the liver, the appearance of increased 

 ketone bodies in the blood and urine of animals having fatty livers would be 

 circumstantial evidence of an increased fat breakdown. On the other hand, 

 one might argue that the rate of ketone body production was unchanged in 

 the fasting animal with a fatty liver, as compared with a normal fasting 

 animal. The reason why a ketonuria of considerable magnitude would 

 develop in the first case, while only a slight and irregular ketonuria would 

 occur under the second condition, would then be referable to the inability 

 of the rats with fatty livers to oxidize the ketone bodies as effectively as do 

 normal fasting animals. However, the liver is not the principal organ for 

 the utilization of ketone bodies; it is the extrahepatic tissues which serve 

 in this capacity. 905 - 906 Moreover the ketone bodies disappear immediately 

 from the urine when glucose is administered. 907 For a further discussion 

 of this phase of the subject, the reader is referred to the section on ketosis 

 (see Chapter III, Volume III). 



The comparative endogenous ketonuria produced in male and female 

 rats during fasting, together with the liver fat values after the administra- 

 tion of the fatty-liver-producing diets for different time intervals, are 

 summarized in Table 26. 



Although no exact relationship exists between the level of liver lipid and 

 ketonuria, a greater decrease in the liver lipids of the females occurs during 

 fasting, coincident with the higher ketonuria in this sex. MacKay et al. m 

 are of the opinion that neither the level of liver fat per se nor any of the 

 agents such as choline, methionine, or cystine which are known to influence 

 the amount of fat in the liver have a significant effect on the level of fasting 

 ketosis. However, Roberts and Samuels 909 have arrived at opposite con- 



904 D. L. MacLean, J. H. Ridout, and C. H. Best, Brit. J. Exptl. Pathol, 18, 345-354 

 (1937). 



905 1. L. Chaikoff and S. Soskin, Am. J. Physiol., 87, 58-72 (1928-1929). 



906 D. R. Drury, R. Barnes, P. O. Greeley, and A. Wick, Am. J. Physiol, 129, 348P- 

 349P (1940). 



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



908 E. M. MacKav, H. O. Carne, A. N. Wick, and F. E. Visscher, /. Biol. Chem., 141, 

 889-896 (1941). 



909 S. Roberts and L. T. Samuels, J. Biol. Chem., 151, 267-271 (1943). 



