238 P. SOUPART 
4) High protein diet. Effects of high protein diet on free amino acid plasma levels 
have been studied by STEIN ef al.27 and by FRAME*8 by means of ion-exchange 
chromatography. From the results of STEIN’s experiment it was concluded that the 
increase in free amino acid plasma levels, observed 2h after feeding 50 g of casein 
to a normal subject, reflects to some degree but not in detail the amino acid com- 
position of the casein fed. Such a protein meal does not lead to more than a 2-fold 
increase of concentration for the involved amino acids. Similar but more detailed 
conclusions are drawn from the experiment of FRAME?8, in which plasma free amino 
acid levels were determined in peripheral blood, in a group of six normal subjects, 
at intervals up to 8h after a high protein meal. Most of the amino acids increased 
TABLE V 
BLOOD AMINO ACID CLEARANCES 
Literature data. Values are expressed in ml/min, corrected or non-corrected for 1.73 sqm. 


Sourarrs CHRENe Evers (Dene Westar, DOOtAN™ raise 
5 subjects(2) 3 subjects 3 subjects 4 subjects ro subjects 4 subjects 5 adults 
Histidine 2.0-16.3 4.5-4.9 I.1-7.5 4.7 — 9.7 I.4 -15.0 4.6 -8.5 5.2-8.7 
Taurine 3.3-12.4 3.-4-3.5 1.6-6.1 I.7 —14.0 0.2 —20.0 = — 
Glycine 2.5- 6.7 3.2—5.6 1.5—-5-7 2.7 — 5.8 1.8 -19.0 4.0 —6.3 1.0—-7.2 
Serine 1.0—- 3.7. 1.8-2.9 - 1.9 — 3.1 1.5 — 5.0 T2—220) 7 = 383 
Tyrosine 0.6= 2.3 0.8=1.3 0.9=1-5 ON ality 0.7 — 3.8 I.2 —2.4 0.5—4.0 
Phenylalanine 0.4— 2.0 0O.7-I.I 0.8-1.5 0.7 — 1.4 0.5 — 1.9 0.2 -1.3 0:4—-2.0 
Methionine 0.7— 7.6 0.9-1.3 0.7—-1.6 Tees 0.2 — 3.9 O -0.4 
Threonine 0.4— 2.2 0.7-I.1 — 0.8 — 1.5 OF =) 325 0-5) 1-45) OASEG 
Isoleucine 0.7— 3.3. I-0-2.0 0.3—1.7 0.2 — 1.0 0.3 —2.5 0 -=09 —_ 
Aspartic acid 1.9-18.0 0.6—-0.7 — 2.4 —- — 
Arginine 0.4— 2.5  0.4-0.5 — 0.2 — 0.8 1.4 O 2.5 —- 
Lysine O.I— 0.8 0.2-0.5  0.2-0.5 0.2 — 1.9 -— 0.2 —0.4 = 
Alanine 0.2— 0.9 0.4—-0.7 — 0.3 — 0.9 0.2 — 1.2 0.3 -1.0 0.7—1.9 
Cystine — 0.2-0.5  0.2-0.5 0.7 — 2 _— 0.I —0.3 3.6-6.7 
Leucine 0.2— 0.9 0.3-0.3 0.3-0.5 0.2 — 0.9 0.3 — 2.2 0.2 —0.4 — 
Valine 0.2— 0.4 - O.1—0.2 0.04— O.1 0.04— 0.5 0.04-0.2 0O.I-0.4 

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in concentration after the meal, but the rise did not parallel the relative amino acid 
composition of the food and the relative distribution of the different amino acids 
in the plasma differed from that in the fasting state. The behavior of the observed 
concentrations was not uniform among the different amino acids. Some of them 
increased in concentration, namely valine, leucine and isoleucine, which rose markedly 
after the meal and, even after 8h, were higher than in the fasting state. Others, 
namely alanine and glycine, fell to levels half the fasting values in 6-8 h. 
Renal handling of free amino acids 
It has become usual to evaluate the excretory function of the kidney in terms of 
the filtration-reabsorption theory by means of calculating clearances for the sub- 
stances excreted. It is also done for amino acids. When the available data on indi- 
vidual amino acid clearances are considered, it appears clearly that as a rule the 
References p. 261/262 
