Jane A. Russell 



515 



difficult to compare in a general manner the effects of the thyroid to those of 

 the anterior pituitary on carbohydrate metabolism. Of the experimental 

 observations which have been made in this field, most fall into the following 

 classes: (a) loss of glycogen (and fat) reserves in animals given large amounts 

 of thyroxin, due in all probability to rapid utilization in the hypermetabolic 

 state; (b) abnormalities in glucose tolerance cinves, the "diabetic" type being 



T.^BLE 5 



Dispo.siTiON OF Fed Glucose in Thyroidectomized Rat.s Four Hour.s after Feeding 



(Calculated from table 4) 



associated with hyperthyroidism; and (c) high absorption rates from the 

 gastrointestinal tract of glucose and of other metabolites in hyperthyioidism 

 and low' absorption rates in hypothyroidism, which, according to Althausen 

 and Stockholm,"" explain the altered glucose tolerance curves. The latter effect 

 is of interest as demonstrating one specific effect of the thyroid hormone, but 

 its mechanism is still controversial. 



Recently, specific attempts have been made to determine whether there is 

 any parallelism between the effects of thyroidectomy and hypophysectomy in 

 carbohydrate metabolism luider a ntnnber of different circumstances. In 

 thyroidectomized-parathyroidectomized rats (maintained with calcium lac- 

 tate in their drinking water) the nonfasted carbohydrate levels lie within the 

 normal range (table 4). The levels after 24 hours of fasting also are practically 

 normal; only the muscle glycogen is slightly low, and this is probably the re- 

 sult of muscular tremors due to the concomitant state of hypoparathyroidism. 

 The RQ is normal; but the oxygen consumption is of course quite low. In 

 thyroidectomized rats fed glucose the expected abnormalities— a low metabolic 

 rate and a low rate of absorption of glucose— are found. However, the distri- 

 bution of the absorbed carbohydrate is fairly normal, especially as compared 



