VIII. p:ffects of deficiency in animals 327 



factor in producing liyper\'itamiiiosis A. In further atudiea Kodahl'^' found 

 that large doses of ascorbic acid did not afford significant protection against 

 the effects of massive doses of \itamin A although supplying additional 

 vitamin C was beneficial in counteracting a moderate excess of vitamin A. 

 He stated, moreover, that the mechanism of the toxic effect of excess vita- 

 min A on the cells remains obscure. Morehouse et al}^- found that both 

 the amount and concentration of ascorbic acid in livers of rats were affected 

 by hypervitaminosis A. The concentration of ascorbic acid became pro- 

 gressi\ely lower as the daily dosage of vitamin A was increased (20,000 to 

 80,000 units). Eeg-Larsen and PihP^^ reported that the fall in serum ascorbic 

 acid in rats treated daily with 20,000 to 40,000 units of vitamin A was the 

 same as that in rats showing the same weight loss after paired feeding. 

 Administration of additional ascorbic acid did not protect rats against 

 excessive doses of vitamin A. It would appear from these results that control 

 of food intake may be as important in the study of hypervitaminosis A as 

 it has been shown to be in hypovitaminosis A. 



(2) Vitamin D. Weld^*'' reported that in human subjects vitamin D was 

 more effective under some conditions than ascorbic acid in increasing capil- 

 lary resistance. The possibility that vitamin D affects calcium as a compo- 

 nent of the intercellular cement of the capillaries was not discussed. Bruce 

 and Phillips ^'"^ found no detectable effect of ascorbic acid upon the response 

 to a small dose of vitamin D as determined by the "line test" using rats as 

 experimental subjects. A possible effect of much larger doses of ascorbic 

 acid than were employed would also have been of interest. Kyrki^*^ found 

 that administration of ^'itamin D caused no lowering of the ascorbic acid 

 content of the blood serum in rachitic infants. Lecoq et al}^''^ fed the Ran- 

 doin rachitogenic diet to young rats kept in the dark and found that large 

 doses of ascorbic acid had no effect on the bone structure but prevented 

 alkalosis and neuromuscular disturbances. Later^"*' these same investigators 

 reported that calciferol appeared to exert a depressing effect on the storage 

 of ascorbic acid in guinea pig tissues. 



(3) Vitamin K. No direct relation between ascorbic acid and vitamin K 

 has been shown, but lack of either or both substances reduces the pro- 

 thrombin content of the blood.'" 



"' K. Rodahl, Hypervitaminosis A. Norsk Polarinstitult, Oslo, Skrifter 95, (1950). 

 '" A. L. Morehouse, N. B. Guerrant, and R. A. Dutcher, Arch. Biochem. and Bio- 



phys. 35, 335 (1952). 

 '" N. Eeg-Larsen and A. Pihl, Acta Pharmacol. Toxicol. 7, 367 (1951). 

 "« C. B. Weld, J. Pediat. 9, 226 (1936). 



'" H. M. Bruce and G. K. Phillips, Biochem. J. 32, 1 (1938). 

 »• R. Kyrki, Acta Pediat. 31, 428 (1943). 



'"» R. Lecoq, P. Chauchard, and H. Mazoud, Compt. rend. sac. biol. 138, 835 (1944). 

 ""■ R. Lecoq, P. Chauchard, and H. Mazou^, Compt. rend. soc. biol. 220, 631 (1945). 



