PHARMACOLOGY 



require proportionately less choline than animals, about 9 mg. per kg. 

 of bodyweight. 



As will be seen later (page 600), choline can be replaced to some 

 extent by methionine, but the two substances are only partly biologi- 

 cally equivalent. Choline was a more effective supplement than 

 methionine for the rat, 3-8 parts of the latter being equivalent to i 

 part of the former.^ The total methionine requirement of rats on a 

 choline-free diet was i-a g. per 100 g. of diet ; half of this was required 

 for growth and half for lipotropic purposes. Methionine did not 

 increase the growth rate further when the diet contained 100 to 200 

 mg. of choline per 100 g.^^ Chicks required i % of methionine in the 

 diet for optimal growth,^* and young pigs o-8 % of methionine and 

 o-i % of choline. ^^ 



References to Section 9 



1. H. J. Channon, J. V. Loach and G. R. Tristram, Biochem. J., 



1938, 32, 1322. 



2. W. H. Griffith, /. Nutrition, 1941, 22, 239. 



3. R. W. Engel, ihid., 1942, 24, 174. 



4. H. Pfaltz, Z. Vitaminforsch., 1942, 22, 193. 



5. G. C. Supplee. L. S. Gall and J. F. Caul, /. Dairy Set., 1945, 28, 



435. 



6. H. S. Owens, M. Trautman and E. Woods, Science, 1941, 93, 406. 



7. D. H. Copeland, Proc. Soc. Exp. Biol. Med., 1944, 57, 33. 



8. C. A. Mills, Arch. Biochem., 1942, 1, 73 ; Proc. Soc. Exp. Biol. 



Med., 1943, 54, 265. 



9. A. E. Schaefer, J. M. McKibbin andC. A. Elvehjem, ihid., 1941, 47, 



365 ; J. M. McKibbin, S. Thayer and F. J. Stare, /. Lah. Clin. 

 Med., 1944, 29, 1109 ; F. R. Dutra and J. M. McKibbin, ibid., 

 1945. 30, 301. 



10. C. Entenman and I. L. Chaikoff, /. Biol. Chem., 1946, 138, 477. 



11. O. D. Abbott and C. U. de Masters, /. Nutrition, 1940, 19, 47. 



12. H. Willstaedt, M. Borggard and H. Lieck, Z. Vitaminforsch., 1946, 



18, 25. 



13. C. R. Treadwell, /. Biol. Chem., 1945, 160, 601. 



14. A. A. Klose and H. J. Almquist, ihid., 1941, 138, 467. 



15. A. L. Neumann, J. L. Krider, M. F. James and B. C. Johnson, 



/. Nutrition, 1949, 38, 195. 



10. PHARMACOLOGY OF CHOLINE 



Choline chloride had a value of LD50 equal to 3-4 g. per kg. of 

 bodyweight when given orally to rats in a concentration of 500 to 

 670 mg. per ml. and a value of 6-i g. per kg. when given in a concen- 

 tration of 200 to 400 mg. per ml.^ The addition of i % of choline 



595 



