244 P. SOUPART 
centrated in leucocytes than in plasma. For all other amino acids, without exception, 
concentrations are 4—60 times higher than in the surrounding plasma. In the case 
of aspartic and glutamic acids, concentration ratios may be somewhat in error 
since aspartic acid is present in a very small amount in plasma and glutamic acid 
might have been produced in part by glutamine decomposition. 
b) Platelets. The situation in this reservoir is similar to that found in leucocytes, 
when compared to plasma levels. Comparison of analytical data given in Table VII 
for leucocytes and platelets shows concentration differences between these two 
TABLE VIII 
RELATIVE CONCENTRATION OF FREE AMINO ACIDS IN ERYTHROCYTES, LEUCOCYTES 
AND PLATELETS* 


Amino acid Erythrocytes Leucocytes Platelets 
Taurine 0.72 521 420 
Lysine 0.05 20 6 
Glycine 1.70 24 17 
Alanine 0.83 16 6 
Valine 1.20 14 5 
Leucine 3.00 45 03} 
Isoleucine 0.60 41 m7 
Serine 1.25 43 30 
Threonine 1.23 20 12 - 
Phenylalanine 0.80 50 17 
Tyrosine 0.83 33 13 
Histidine 1.75 8 4 
Arginine Traces — == 
Aspartic acid (185) (1750) (1350) 
Glutamic acid (6) (147) (63) 
Methionine — 58 13 
Cystine 1/, —- 4 -- 
Proline 0.80 10 5 


types of cells which cannot be accounted for on the basis of analytical errors in 
amino acid determination. It -is concluded therefore that the platelet preparation 
was not contaminated to a significant extent by leucocytes. As in the case of leuco- 
cytes, taurine is several hundred times more concentrated in platelets than in plasma. 
Taurine has been shown to derive from cysteine in platelets by means of tracer 
studies. It appears either that sulfur metabolism must be specially active in those 
compartments, or that taurine has a special meaning as an electrolyte since it has been 
calculated that taurine equivalents could balance approx. 70% of the total Na”, 
K*, and Ca?* content of platelets*. 
Errors in concentration measurements of free amino acids in leucocytes and 
platelets are unavoidable, owing to the method used for the separation of the cells, 
since the sediment obtained is made of wet cells and is weighed as such after as 
complete as possible drainage of the excess washing solution. Nevertheless, these 
results clearly indicate that free amino acid concentrations in leucocytes and platelets 
References p. 261/262 
