504 V. BLOOD LIPIDS 



man and Leon. 908 Most animals, including man, respond to either large 

 or toxic doses of vitamin A by increases in serum cholesterol, 882 ' 909 although 

 Muller and Suzman 910 were unable to note any correlation between the 

 amounts of vitamin A and of cholesterol in the livers of patients at autopsy. 

 Fasold 911 reported that large dosages of vitamin A did not produce changes 

 in the cholesterol in the bodies of rats. However, neither of these findings 

 directly refutes the positive results on blood lipids, since variations in blood 

 lipids may occur without influencing the quantity in the liver or total body. 

 Peters and Van Slyke 202 suggested that the hypothesis of a hyperlipemia 

 following excessive vitamin A intake must be discounted, because the 

 vitamin was administered in oil. However, one must question this objec- 

 tion in view of the relatively large quantity of oil required to produce hy- 

 perlipemia. 



In the case of the dog, the hypervitaminosis A is also distinguished by 

 hypervitaminemia A. 851 Serum vitamin A values, which are remarkably 

 high in the normal dog, 849-851 are increased 8- to 40-fold in hypervitaminosis 

 A. A value as high as 6012 microgram per cent has been recorded by Mad- 

 dock et a?. 851 following the administration of vitamin A in the dosage of 

 90,000 /xg-/kg. body weight to a puppy for forty-five days. However, the 

 dog is unusual in its failure to respond to hypervitaminosis A by the de- 

 velopment of hypercholesterolemia 851 - 882 or by an increase in serum phos- 

 pholipids. 851 



The toxicity of hypervitaminosis A may be due to a hypoprothrombin- 

 emia, 912-914 a condition which can be corrected by the administration of 

 vitamin K. 912 Moore and Wang 915 call attention to the prevalence of 

 uterine hemorrhages in pregnant rats given an excess of cod-liver oil. 

 This may also be related to the hypoprothrombinemia. No similar toxici- 

 ties can be produced by the feeding of high dosages of carotene, although a 

 high blood carotene and pigmentation of the skin result. The failure of 

 carotene to effect a hypervitaminosis A similar to that caused by excessive 

 doses of vitamin A per se may be due to the limited absorbability of the 



908 P. E. Rothman and E. E. Leon, Radiology, 51, 368-374 (1948). 



909 F. Lasch, Klin. Wochschr., 13, 1534-1536 (1934). 



910 G. L. Muller and M. M. Suzman, Arch. Internal Med., 54, 405-411 (1934). 



911 H. Fasold, Z. ges. exptl. Med., 94, 35-37 (1934). 



912 R. F. Light, R. P. Alscher, and C. N. Frey, Science, 100, 225-226 (1944). 



913 S. E. Walker, E. Eylenburg, and T. Moore, Biochem. J., 41, 575-580 (1947). 



914 C. L. Maddock, S. B. Wolbach, and D. Jensen, Federation Proc, 7, 275 (1948). 



915 T. Moore and Y. L. Wang, Biochem. J., 39, 222-228 (1945). 



918 K. Rodahl, The Toxic Effect of Polar Bear Liver, Skrifter No. 92, Norsk Polarin- 

 stitut, Kommisjon Has Jacob Dybwad, Oslo, 1949, 99 pp.; cited by T. Moore, Ann. 

 Rev. Biochem., 19, 319-338 (1950), p. 325. 



