CAKBOHVDl^ATK MKTAKOLISM IN HKLATIOX To TllK THY- 

 KOII) (iLANI). II.: Till-: KFFKCT ( »F TH V IJoI h KKKI »I \(; 

 OX THE (iASEOUS METABOLISM. By W. < kamkk aiul H. 

 M'Call.' (From tlie Imperial Cancer Research Fund. Lomlon, and 

 from the I'hysioloi^y Department, Edinburtjh F Diversity.) (With 

 eleven figures.) 



{Received for publkalioii 2iul Scjileinhcr 1916.) 

 InTK(»I)IjCT10\. 



The following investigation was carried out in continuation of previous 

 studies on the influence of the thyroid secretion on carbohydrate meta- 

 bolism. Cramer and Krause (1) had found that feeding with thyroid 

 gland produced after two or three days a complete disappearance of 

 glycogen from the liver, even when the animals (rats and cats) were kept 

 on a diet rich in carbohydrates (e.g. bread and milk). It was further 

 noted that under these conditions no sugar appealed in the urine, whereas 

 glycosuria would be expected on the basis of the current conception of 

 carbohydrate metabolism. 



There are three possibilities which might account for this apparently 

 paradoxical condition of carbohydrate metabolism. Either the suspension 

 of the glycogenic function of the liver is compensated for by an increased 

 deposit of glycogen in the muscle — and a slight increase so far as absolute 

 amounts are concerned would be sufficient to account for the amount of 

 carbohydrate normally deposited in the liver. Or, secondly, one might 

 postulate for the thyroid hormone a direct stimulating effect on the oxida- 

 tion of carbohydrates, so that the disappearance of glycogen from the liver 

 would have to be interpreted as an effect secondary to the increased oxida- 

 tion of carbohydrates. Or, thirdly, carbohydrates might be transformed 

 into and deposited as fat. This last possibility can be dismissed at once, 

 since the rapid disappearance of fat under the influence of thyroid feeding 

 is a well-established fact. The first possibility that the muscles act 

 vicariously for the liver as gl3^cogen depots was tested by R. A. Krause (2) 

 by determining the glycogen content of the muscles of thyroid-fed 

 animals. Since in such animals the glycogen percentage of the muscles 

 is not increased, this possibility can be excluded. The second and last 

 possibility, which depends on the assumption that the thyroid secretion, 

 acting as a true hormone in Schafer's definition of the term (3), directly 



' Carnegie Research Scholar, 1914-1915. 



