FREE AMINO ACIDS IN ANIMAL TISSUE 327 
on livers of rats at 12h and 2 and 6 days after laparotomy (controls) and at 12h, 
and I, 2, 3, 6 and g days after removal of two-thirds of the liver mass. Chromato- 
grams of extracts prepared from livers of unoperated rats are shown in Figs. 231 
and 232 and comparisons of livers of laparotomized and hepatectomized animals 
at 12 h and 2 and 6 days are shown in Figs. 233-238. The surgical procedure involved 
in the laparotomy produced virtually no observable effect on the distribution of 
detectable ninhydrin-reactive constituents. However, even at 12h after partial 
hepatectomy (Fig. 234) there was a marked increase in the content of glutamic acid, 
a small relative increase in aspartic acid, and notable decreases in taurine and 
glutamine. The extract from the liver sample obtained at this time was the only 
one which showed the presence of a-amino--butyric acid. At 1-6 days after partial 
hepatectomy there was an elevation in the content of ethanolamine phosphate and 
glutathione as well as of glutamic and aspartic acids, as reported previously*’. In 
addition, serine was higher than in the controls during this period. At no time was 
an increase inlysine detected. The taurine and glutamine levels returned to normal 
by the 6th day. The extracts obtained at 9 days from the livers of the experimental 
animals were normal in all respects. 
The relative increases in glutamic acid and decreases in glutamine contents ob- 
served during the most active phases of regeneration (up to 3 days) might be attri- 
buted to a greatly increased rate of utilization of the glutamine amide nitrogen for 
reactions in which the amide group is used specifically, such as purine, glucosa- 
mine*’, and diphosphopyridine nucleotide* biosyntheses. The increase in ethanol- 
amine phosphate may reflect the decreased rate of synthesis of phospholipids ob- 
served after partial hepatectomy*®: 4’. The lowered taurine level may result from 
the decreased availability of cystine for synthesis of taurine, the function of which 
in the free form is still not known, because of the increased rate of utilization of 
cystine for the synthesis of protein and glutathione. 
Considering the multitude of major physiological and biochemical alterations 
which take place in liver during regeneration after partial hepatectomy**: 9, it is 
remarkable that relatively few changes were observed in the distribution of easily 
extractable ninhydrin-reactive constituents. 
Effect of hormones on prostate and uterus. Orchiectomy produces atrophy of the 
prostate and ovariectomy acts similarly on the uterus. Concentrations of free amino 
acids were found by paper chromatography to decrease profoundly in the prostate 
after castraction and atrophy, and normal levels of these constituents were restored 
by administration of testosterone propionate*®: 4°. Treatment of normal male rats 
with testosterone, progesterone, or estradiol produced little effect on amino acid 
distribution of the prostate. A similar study was performed recently®® in which 
column-chromatographic determination was made of ninhydrin-reactive constit- 
uents in tungstate filtrates of uteri of ovariectomized rats before and at 4 and 
24h after the administration of estradiol. With the exception of a decrease in taurine 
Figs. 231-238. Amino acids in liver (75 mg) at various times after partial hepatectomy. Figs. 231, 
232: unoperated controls. Fig. 233: laparotomized, 12h. Fig. 235: 2 days. Fig. 237:6 days. Fig. 234: 
partially hepatectomized, 12h. Fig. 236: 2 days. Fig. 238: 6 days. Taurine, 5; glutamine, 13; 
glutamic acid, 17; aspartic acid 18; ethanolamine phosphate, 19; glutathione, 21. 
References p. 348/349 
