90 



V. DU VIGNEAUD et al. 



VOL. 12 (1953) 



indicated in Table II, deuterium oxide was administered in the drinking water at a level 

 of 10 atom per cent for 4 days and then at a level of 4 atom per cent, for the remainder 

 of the 3-week experimental period. The animals were then sacrificed with chloroform and 

 immediately frozen in dry ice. 



TABLE II 



WEIGHTS OF ANIMALS IN GRAMS 



Day of Experiment 



38 



57 



78 



Rat No. 



Sex 



Weaned 



Initial 

 Diet 



Choline * 

 removed 



DoP 



begun 



Sacrificed 



* Rats 42 and 43 were continued on the initial choline-containing diet; rats 44 and 45 were 

 placed on a diet in which the choline was replaced by methionine. 



t Rats 30 and 31 were begun on the amino acid diet at weaning, choline was removed 30 days 

 later, DgO was begun 79 days later and the animals were sacrificed on the looth day. 



The choline was isolated as the chloroplatinate and degraded to trimethylamine 

 according to procedures described previously^. The average deuterium content of the 

 body water during the last 3 weeks of the experiment was determined by measuring 

 by the mass spectrometer method^^'^^ the deuterium content of water from the pooled 

 urine of each animal for this period. The deuterium contents of the trimethylamine 

 chloroplatinates were likewise determined. These values were then used to calculate 

 the extent to which the deuterium of the body water had been incorporated into choline 

 methyl groups. The experimental results are summarized in Table III. 



TABLE III 



ISOTOPIC CONTENTS OF BODY WATER AND CHOLINE METHYL GROUP 



These rats on the labile methyl-free diet. 



References p. 91. 



