471 
INVITED DISCUSSION 
A SURVEY OF THE AMINO AGIDS 
AND - KELATED COMPOUNDS IN NERVOUS. TISSUE 
Ee Ae IAIN 
The Rockefeller Institute, New York, N.Y. (U.S.A.) 
The following tables present a compilation of the reported values for the concentra- 
tion of amino acids and related substances in the normal nervous tissue of various 
species of animals. The accompanying text gives such discussion as is necessary to 
explain the tables and, also, assembles certain data that could not be included 
because of limitations of space. These data consist, for the most part, of the results 
of two types of studies: studies on the distribution of a compound in parts of the 
central nervous system and developmental studies on the variation in the concentra- 
tion of a substance with the age of the animal. 
The values presented appear as ranges, in those cases for which much information 
is available; as averages, in the few cases for which the literature values are almost 
the same; or as individual figures, when only one or two determinations have been 
made. In general, the values given as ranges will be found to be the most reliable, 
though perhaps somewhat all-encompassing. Values that are far outside the usual 
range of figures, or which are the result of techniques which seem of doubtful validity, 
have been omitted from the tables. 
All values have been expressed as wmoles/g of fresh tissue. Since this has involved 
a great deal of recalculation and, occasionally, the making of what it is hoped are 
reasonable assumptions, it is also to be hoped that not too many errors have crept 
in. However, in dealing with such a wide variety of compounds, the usefulness of 
stating concentrations in moles becomes all the more apparent. Not only are com- 
parisons among compounds facilitated, but any possible ambiguity is removed 
concerning the form in which a substance has been measured (as the - HCl or free 
base, for example). Furthermore, since modern analytical procedures most often 
give as the primary observed datum the molar quantities of some constituent part 
of the molecule, it seems far more logical to keep the results in moles, particularly, 
as is the case with the lipids, when a molecular weight must be assumed. The use 
of fresh weight of tissue as the base line is a personal preference of the author’s, 
founded, however, on the fact that the wet weight is the original measurement. 
Glutamic acid and glutamine (Tables IA and B). Glutamic acid and its derivatives 
are considered to be the characteristic amino acid constituents of nervous tissue. 
The central position of glutamic acid in the metabolism of nervous tissue has been 
discussed many times in recent years®, 158, 165, 166, 171, 172, 174-176 and its function in 
* Present address: Geigy Research Laboratories, Ardsley, N.Y. (U.S.A.). 
References p. 482/485 
