430 G. ROUSER et al. 
This change in the method of study was made to determine whether a saline infusion 
would change the permeability of erythrocytes to glutamine. It was suspected that 
the red cells might show increased permeability to amino acid by virtue of some 
marked differences in results reported in the literature for the rate of equilibration 
of erythrocytes with plasma after ingestion as opposed to infusion of amino acids. 
The plasma free amino acid levels of subject H. Bie. are shown in Figs. 304-308 
and 314-318. The same rise and fall of glutamine, glutamic acid, and the unknown 
substance to the left of glutamic acid, as well as a gradual decrease of taurine followed 
by a return to somewhat above the control level, are in agreement with the findings 
with other normal subjects and patients with leukemia. Of considerable interest is 
the fact that the glutamic acid level did not return completely to the control level as 
observed for other subjects. The plasma glutamate level in this subject (H. Bie.) re- 
mained moderately high even after glutamine had returned to the control level. 
A very clear venipuncture response is shown in Figs. 304-306. The fall in taurine, 
glutamic acid, and aspartic acid is very clear and was maximal 40 min after the first 
venipuncture. 
The chromatographic results with erythrocytes from subject H. Bie. are shown 
in Figs. 309-313 and 319-323. The chromatograms are of considerable interest in 
that a rapid equilibration of plasma and erythrocyte glutamine levels is illustrated. 
The first sample drawn 15 min after ingestion of glutamine (Fig. 311) was very 
similar to the pre-ingestion controls (Figs. 309, 310), while the sample obtained at 
30 min (Fig. 312) showed a greatly elevated glutamine level that corresponded to 
the elevation of the plasma glutamine level (Fig. 307). It is to be recalled that the 
saline infusion was begun just before the 15-min blood sample was drawn. Rapid 
equilibration of erythrocyte and plasma glutamine levels appears to have followed 
the beginning of the infusion. There was a decrease of taurine below the control 
level (apparent up to the 70 min sample) followed by a return to the control level. 
All samples drawn after the saline infusion was begun showed close correspondence 
of plasma and erythrocyte glutamine levels. After the cessation of the saline infusion 
(between the 70 and 145 min samples) the erythrocyte levels were first higher than 
the plasma levels. The erythrocyte level then fell and again matched the plasma level 
as shown in Figs. 318 and 323. It can be concluded that the saline infusion was related 
to a rapid equilibration of plasma and erythrocyte glutamine levels, and that, after 
infusion was stopped, the rapid equilibration no longer existed. This interpretation 
is in keeping with the results from the other eight ingestion studies in which the 
absence of the saline infusion was associated with a failure of erythrocytes to reflect 
the changes in plasma glutamine levels to the same extent. The permeability of 
erythrocytes for amino acids appears to be altered 7m vitro when a solution of amino 
acid is added to plasma (see part I) in which the cells are incubated. This 7 vitro 
result is thus in keeping with the findings 7m vivo after saline infusion. 
It is perhaps surprising that such a small quantity of saline given over a relatively 
long period of time (1.5 h) should have such an effect. It appears, however, that 
there are marked changes in erythrocyte permeability for some compounds in vitro 
and 7m vivo when relatively small amounts of salt solutions are added to blood. 
These permeability changes are not apparent for all of the amino acids in the ery- 
throcyte free amino acid pool. The levels of some of the free amino acids remain 
relatively constant. 
References p. 447/448 
