454 E. V. FLOCK AND J. L. BOLLMAN 
cardiac muscles of the rat after removal of the liver when the rat was maintained 
with glucose and insulin (Figs. 1-3). There was a more rapid and greater increase in 
glutamine in the brain (Fig. 4). 
Effect of insulin on anuno acids. When the dehepatized rats were maintained with 
glucose but without insulin, the rate of increase of free amino acids in plasma and 
muscles was much greater than in the presence of insulin (Fig. 1-3). The amino 
acids in the brain, however, increased at the same rate whether or not insulin was 
administered. Glutamine usually increased more in the brain than in the plasma or 
muscles. 
Effect of body temperature on the amino acids. When the eviscerated rats were sepa- 
rated into two groups depending on whether their body temperature was less or 
more than 32° at the end of the experiment, a clear-cut difference in the level of 
amino acids was found. The rate of increase of the amino acids in plasma and tissues 
was much slower in rats at the low temperature than at the more nearly normal 
temperatures. The levels of amino acids found in rats at temperatures exceeding 
32° were higher than those found in dehepatized dogs*. This may be due to the higher 
rate of metabolism in rats. Approximately the same percentage of amino acids was 
found to be glutamine in plasma and skeletal muscle, whether the temperature was 
more or less than 32° and whether or not the rat was given insulin. The percentage 
of glutamine appeared to be characteristic of the tissue, not of the treatment. In 
the brain, however, glutamine accounted for approximately 20% of the free amino 
acids in the normal rat and for at least 50% of the extra free amino acids which 
appeared in the brain after evisceration of the rat. 
Effect of adrenalectomy. When the adrenal glands were removed at the time of evis- 
ceration or 1-2 days earlier, little difference occurred in the rate of increase of the 
total free amino acids in plasma, brain, skeletal and cardiac tissue if the temperature 
of the rats did not exceed 32°. The survival time of rats with temperatures exceeding 
32° was short; therefore, the rats at this temperature were studied only at 6h after 
evisceration. The increase in total free amino acids in the brain was less at 6 h after 
evisceration with removal of the adrenals than in the rats with adrenals, whereas 
the increases in the amino acids of plasma and skeletal muscle were relatively small 
at 6 h whether or not the adrenals were present. Again, the changes in glutamine 
paralleled the changes in total free amino acids, and thus the accumulation of gluta- 
mine in the warmer rats was less at 6h in rats without adrenals than in those with 
adrenals. INGLE, PRESTRUD AND NEzAmIs”2 found that adrenalectomy suppressed 
the level of amino acids of the eviscerated rat at each dose-level of insulin and 
glucose. 
Effect of administration of ammonium citrate or glutamine. When ammonium citrate 
was administered to a normal rat at the rate of 1 mg of N/h for 24h, no change 
was found in the glutamine content of brain or muscle (Table I). When this substance 
was administered to eviscerated rats for 17 to 19 h, however, the glutamine content 
of the brain increased greatly without any apparent increase in other amino acids. 
The levels of glutamine in the brain were greater than those found in dehepatized 
References p. 460 
