300 E. ROBERTS AND D. G. SIMONSEN 
certain aspects of the amino acid pattern of tissues become established at a given stage in 
development, one or more of the amino acids may still continue to change in concentration 
before the adult pattern is established. To date only in the case of GABA has the content 
of an amino acid been related to the increase in activity of the enzyme which forms 
this amino acid. 
RELATIVE CONSTANCY OF THE FREE AMINO ACID PATTERNS OF TISSUES: 
EXPERIMENTAL ALTERATIONS 
At any time, the concentration of a particular constituent in a cell must be, at the 
least, the function of the rate of entry, exit, formation, utilization and possible 

109 110 

111 : wren." 
Figs. 107-120. Free amino acids of left ventricle of dog heart (75 mg) at various times after 
ligation of the anterior descending coronary artery. The odd numbered figures show the unin- 
farcted areas and the even numbered figures the infarcted areas. Figs. 107, 108: 2h. Figs. 109, 
PRO 4 Me eS) nue nate) Le 
References p. 348/349 
