AMINO ACID TRANSPORT IN EHRLICH CELLS 541 
tumor cells was made by CHRISTENSEN et al. by the discovery, that pyridoxal and 
some other compounds markedly enhance glycine accumulation by these cells. 
This observation has been confirmed by other laboratories including our own. Since 
however, we never succeeded in accelerating the glycine influx by pyridoxal under 
a variety of conditions we had to conclude on the basis of the above model, that the 
effect of pyridoxal increases accumulation by means other than stimulating the 















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2 4 6 8 2 4 6 8 
Time(min) Time (min) 

Fig. 4. Effect of 1 mM pyridoxal on glycine distribution and fluxes. Left side, distribution ratio 
(R,) of total glycine (dotted line) and of radioactivity (solid lines) with and without pyridoxal. 
Right side, analysis of these data according to the equation of HeE1Nz*!, in order to determine 
the flux coefficients’. (Fig. reproduced by permission of Springer-Verlag). 
transport mechanism*. In recent studies with BITTNER we confirmed this by showing 
that pyridoxal, while strongly enhancing the steady state level of glycine, leaves 
the influx unchanged but markedly reduces the efflux coefficient!’ (Fig. 4). This 
could mean, that pyridoxal reduces the exit of glycine without influencing the 
transport mechanism. The accumulation of a-aminoisobutyric acid, however, is 
hardly increased by pyridoxal (Table I). Since this amino acid probably enters and 
leaves this cell by the same pathways as does glycine, pyridoxal seems to affect 
neither the entry nor the exit mechanism of glycine. It rather should concern some 
TABLE I 
EFFECT OF PYRIDOXAL ON ACCUMULATION OF GLYCINE AND 
AMINOISOBUTYRIC ACID IN EHRLICH ASCITES TUMOR CELLS 
After 1 h at 37°. 
Distribution ratio 
Addition to medium pee acer 

2 mM [1-4C]glycine 7.9. 
2mWM [1-#4C}glycine + 1 mM pyridoxal 18.1 
2 mM [1-4Cjaminoisobutyric acid 10.2 
2 mM [{1-14C|aminoisobutyric acid 
+ 1 mM pyridoxal 11.6 

* Unpublished observations. 
References p. 544 
