Uptake for glutamate and aspartate in both retina and synaptosomes was
found to be saturable, temperature sensitive, sodium dependent and re
duced by metabolic inhibitors. The P-1 and P-2 synaptosomal fractions
showed high affinity systems for glutamate (3 and 9 mu M) and aspartat
e (6 and 3 mu M) respectively. Early after birth, glutamate accumulati
on was much higher than that of aspartate. It showed a rapid increase
reaching the adult values about day 15. Aspartate uptake progressively
increases with age up to about day 30. Our findings suggest that glut
amate and aspartate may be transmitters at specific cell populations i
n the rat retina.