HIGH-AFFINITY UPTAKE OF GLUTAMATE AND ASPARTATE IN THE DEVELOPING RATRETINA

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.