FREE AMINO ACIDS IN ANIMAL TISSUE 287 
normal tissue, including every type of blood cell, has a distribution of easily extractable 
ninhydrin-reactive constituents which 1s characteristic for that tissue. In healthy organ- 
isms the patterns are specific and consistent so that with some experience it is 
possible to determine the tissue studied upon inspection of the chromatogram. A 
remarkable constancy of distribution of ninhydrin-reactive constituents was ob- 
served from one animal to another in the case of adult mice and rats of a particular 
strain. This is illustrated in Figs. 5—12 in which are shown chromatograms made of 
extracts of brain from mice of the Swiss strain of both sexes ranging between 16.9 
and 18.5 g in weight. A similar constancy in amino acid distribution was found in 

16 
Figs. 13-16. Amino acids in extracts of the myocardium of the different chambers of dog heart 
(75 mg). Fig. 13: left ventricle. Fig. 14: right ventricle. Fig. 15: left auricle. Fig. 16: right 
auricle. Taurine, 5; alanine, 8; glutamine, 13; glutamic acid, 17; cystine (cysteic acid), 20; 
oxidized (H,O,) glutathione, 21. 
the brains of young adult Sprague-Dawley rats and in other tissues of these and 
other species. 
Reproducible differences in amino acid pattern can be found even within one organ 
as illustrated in the patterns of the auricles and ventricles of the dog heart (Figs. 
13-16)", The ventricular pattern in a number of dogs differed from that found in 
the auricles, the glutamine and alanine levels of the ventricle being found to be 
somewhat higher and the taurine level generally somewhat lower than that found 
in auricular tissue. The chief ninhydrin-reactive constituents found in the extracts 
of dog heart were glutamine, alanine, taurine and glutamic acid, the same amino 
acids that were prominent in the extracts of other mammalian hearts. The above 
point is illustrated further by the demonstration in Figs. 17-22 of the variations in 
the amounts of ninhydrin-reactive constituents noted in different parts of rat brain, 
the most marked difference being found in the content of y-aminobutyric acid 
References p. 348/349 
