CHOLINE 



were less easily metabolised and thus accumulated in the liver.^' Ino- 

 sitol may likewise owe its lipotropic effect to its incorporation into 

 phosphoHpids. The ethyl homologue of choline (page 603) is also 

 lipotropic and can likewise be incorporated into phospholipid mole- 

 cules. It has been suggested ^s that the action of insulin in depan- 

 creatised dogs may be to liberate bound methionine from the dietary 

 protein, making it available for the synthesis of choline, which then 

 exerts a lipotropic effect. 



Choline is also responsible for certain in vivo methyl ations, it 

 stimulates growth and it prevents perosis in chicks and turkeys. 

 Little is known about the manner in which choline exerts these effects, 

 but they appear to be independent properties of the choline molecule, 

 since closely related analogues only possess one or, at most, two of 

 these functions (page 603). 



Finally, choline is the precursor of acetylcholine and, indeed, it 

 has itself a vasodilator action, although much less marked than that 

 of acetylcholine (page 596). 



References to Section 13 



1. H. F. Tucker and H. C. Eckstein, /. Biol. Chem., 1937. 121, 



479- 



2. S. A. Singal and H. C. Eckstein, Proc. Soc. Exp. Biol. Med., 1939, 



41, 512. 



3. W. C. Rose and E. E. Rice. /. Biol. Chem., 1939, 130, 305. 



4. V. du Vigneaud, H. M. Dyer and M, W. Kies, ibid., 1939, 130, 



325 ; V. du Vigneaud, J. P. Chandler, A. W. Moyer and D. M. 

 Keppel, ibid., 1939, 131, 57. 



5. V. du Vigneaud, M. Cohn, J. P. Chandler, J. R. Schenck and S. 



Simmonds, ibid., 1941, 140, 625. 



6. D. Stetten, ibid., 1941, 138, 437. 



7. K. Bloch and R. Schoenheimer, ibid., 167. 



8. H. Borsook and J. W. Dubnoff, ibid., 1940, 132, 559. 



9. H. Borsook and J. W. Dubnoff, ibid., 1945, 160, 635. 



ID. M, Cohn, S. Simmonds, J. P. Chandler and V. du Vigneaud, ibid., 

 1946. 162, 343. 



11. M. Womack and W. C. Rose, ibid., 1941, 141, 375. 



12. H. J. Almquist and C. R. Grau, /. Nutrition, 1945, 29, 219. 



13. C. R. Grau and H. J. Almquist, ibid., 1943, 26, 631. 



14. T. H. Jukes, /. Biol. Chem., 1940, 134, 789 ; /. Nutrition, 1941, 



22, 315- 



15. T. H. Jukes, ibid., 1941, 20, 251. 



16. H. J. Almquist and C. R. Giau, ibid., 1944, 27, 263 ; C. R. Grau 



and H. J. Almquist, ibid., 1943, 26, 631. 



17. D. S. McKittrick, Arch. Biochem., 1947, 15» I33 ; 1948, 18, 437. 

 17a. W. Sakami, /. Biol. Chem., 1949, 179, 495. 



18. H. J. Almquist and C. R. Grau, /. Biol. Chem., 1943, 149, 575. 



602 



