708 XI. VITAMINS E (tocopherols) 



(c) Effect on the Synthesis of Phosphoglucomutase. One may criticize 

 the use of a-tocopheryl phosphate rather than free tocopherol in the alco- 

 hol form or the tocopherol-protein complexes which Ames and Risley'^^ 

 have shown are the naturally-occurring forms of vitamin E. However, 

 when the tocopherol is introduced by feeding or injecting a-tocopherol 

 phosphate into the animal before sacrifice, the isolated skeletal muscle 

 of the normal rat still exhibits a depressed oxygen consumption. This 

 defect in carbohydrate metabolism is believed to reflect a depressed rate of 

 synthesis of phosphoglucomutase, which like other enzymes contains a 

 protein moiety. ^- 



{d) Effect on Glycogen and Blood Glucose. When tocopherol was ad- 

 ministered to normal rats or to animals made diabetic with alloxan, no 

 effect on the respiratory quotient, li\'er or muscle glycogen could be ob- 

 served, and the carbohydrate metabolism was not affected, except that an 

 increase in heart glycogen occurred. '^* On the other hand, when tocopherol 

 was given to fasting diabetic human subjects, blood sugar was reduced. ^^^ 

 It was also noted that tocopherol acts synergistically with insulin in de- 

 creasing the glycemia.^^ Gounelle et al.^^ also found that rabbits made 

 diabetic with alloxan were relieved by a-tocopherol. Toxicity was re- 

 duced, and the blood sugar levels were 50% lower. 



The administration of a-tocopherol was reported to be effective in reduc- 

 ing the blood sugar level of normal dogs as well.^*^ It is suggested by Gray 

 and De Luca^^^ that tocopherol acts under such conditions to speed up the 

 equilibrium, "blood glucose :^ tissue glycogen." It was also suggested 

 by the latter investigators^^^ that a-tocopherol has an insulin-Uke effect. 

 This hypothesis was supported by the results of Butturini and Baron- 

 chelli,^^^ who found that tocopherol administered with insulin increased its 

 effect. However, Gray and De Luca^^^ were later unable to obtain con- 

 firmation for this hypothesis in in vitro tests with diaphragm On the 

 other hand, Milman and collaborators^^' observed deficient deposition of 

 administered glycogen in the muscle and liver of vitamin E-deficient 

 rabbits, although glucose absorption and the blood glucose levels were 



183 S. R. Ames and H. A. Risley, Ann. New York Acad. Sci., 52, 149-155 (1949). 



1" G. La Grutta and A. Cilento. Boll. soc. ital. biol. sper., 29, 408-410, 1084-1085, 

 1573-1575, 1575-1578(1953). 



i«5 H. Gounelle, C. Marnav, and H. Rabbii, Presse med., 62, 888-890 (1954). 



166 D. E. Gray and H. A. De Luca, Rev. can. biol, 11, 64 (1952). 



1" U. Butturini and A. Baronchelli, Giorn. din. med. (Parma), 32, 917-934 (1951); 

 Chem. AbsL, 47, 7677 (1953). 



168 D. E. Gray and H. A. De Luca, Canad. J. Biochem. Physiol, 32, 491-497 (1954). 



169 A. E. Milman, A. M. Treacy, and A. T. Milhorat, Federation Proc, 13, 100-101 

 (1954). 



