CONVERSION OF FAT TO CARBOHYDRATE 229 



hormone. Ringer"" and others"^""' reported that no increased sugar ex- 

 cretion occurs in the urine of phlorhizinized dogs if the glycogen reserves are 

 first exhausted. Likewise, Kramer and co-workers'^^ reported similar re- 

 sults on depancreatized dogs. Moreover, no glycosuria occurs in normal 

 dogs following the administration of epinephrine if the glycogen stores have 

 previously been depleted."^ 



On the other hand, Chaikoff and Weber^'^ interpreted their data on the 

 effect of repeated injections of epinephrine into fasting depancreatized dogs 

 as indicating a formation of carbohydrate from fatty acids. Macleod,' 

 commenting on these experiments, states that they prove "irrefutably the 

 derivation of sugar from fatty acids, at least in diabetic animals." How- 

 ever, a number of investigators have failed to confirm these tests, and one is 

 led to question them. One criticism is that Chaikoff and Weber failed to 

 consider muscle glj'cogen as a possible source of the sugar excreted. Cori 

 and Cori"^-''^ reported that an increase in blood lactic acid follows the ad- 

 ministration of epinephrine to rats, concomitantly with a lowering in the 

 level of muscle glycogen. As a confirmation of this latter viewpoint, one 

 may cite the results of Bollman and collaborators. ^'^ These workers re- 

 ported that the extra sugar excreted by depancreatized dogs, over and 

 above the 2.8: 1 ratio following the administration of epinephrine, was prac- 

 tically identical with that calculated as originating from the muscle gly- 

 cogen which disappeared. Similar data have been recorded by Chambers 

 and co-workers,^* and also by Bachrach, Bradley, and Ivy.'^° Actually, the 

 latter group calculated the average potential glucose in their depancrea- 

 tized dogs, after a three-day fast, as 25.8 g., of which 13.9 g. came from 

 muscle glycogen. The actual extra glucose excreted amomited to a mean of 

 only 13.2 g., so that it is entirely unnecessary to postulate that the extra 

 glucose under such conditions arises from fat. Thus, it is apparent that the 

 fat -»• carbohydrate reaction does not gain any substantial support from 



ii» A. I. Ringer, /. Exptl. Med., 12, 105-113 (1910). 

 1" R. T. Woodyatt, /. Biol. Che?n., U, 441-451 (1913). 

 i'2 W. D. Sansum and R. T. Woodyatt, /. Biol. Chem., 21, 1-21 (1915). 

 "3 R. W. Seuffert and H. Hartmann, Beitr. Physiol, 2, 199-204 (1924). 

 11^ B. Kramer, J. Marker, and J. R. Murlin, /. Biol. Chem., 27, 499-515 (1916). 

 1'* F. Hildebrandt, Nanny n-Schmiedeberg's Arch, exptl. Pathol. Pharmakol., S8, 80- 

 112(1920). 



'!« I. L. Chaikoff and J. J. Weber, /. Biol. Chem., 76, 813-832 (1928). 

 »" C. F. Cori and G. T. Cori, J. Biol. Chem., 79, 309-319 (1928). 

 "8 C. F. Cori and G. T. Cori, /. Biol. Chem., 84, 683-698 (1929). 

 >'9 J. L. Bollman, F. C. Mann, and C. M. Wilhelmj, /. Biol. Chem., 93, 83-91 (1931). 

 'i^W. H. Bachrach, W. B. Bradley, and A. C. Ivy, Am. J. Physiol., 117, 203-205 

 1936). 



