the uptake of tritium-labeled l-leucine , l-lysine , l-aspartic acid , and glycine by neurons and astrocytes isolated from the cerebral cortex of 3-week-old rats was followed for varying periods up to 40 min at amino acid concentrations from 1 to 2000 micromol/liter in medium .
C0017890
glycine
C0002520
amino acid