Uptake of (3H)glycine and (14C)glutamate by cultures of chick spinal cord.

1. Spinal cord explants from chick embryos, grown in culture for up to 16 days, rapidly accumulated [(3)H]glycine and [(14)C]glutamate when incubated at 25 degrees C in a medium containing either 2 x 10(-10)M glycine or 4.8 x 10(-8)M glutamate.2. After 90 min incubation, a tissue/medium ratio of 60:1 and 20:1 was attained for [(14)C]glutamate and [(3)H]glycine respectively.3. The uptake systems, in addition to requiring sodium ions in the medium, were temperature sensitive, showed saturation kinetics, and were inhibited by ouabain.4. For the glutamate and glycine accumulation the K(m) value was 4.3 x 10(-5) and 4.1 x 10(-5)M respectively, indicating that a high affinity uptake process is involved.5. The rate of accumulation of both glutamate and glycine increased in cultures between the ages of 3 and 10 days thus matching their morphological development.6. In light of previous evidence, the demonstration of an active transport mechanism for both glutamate and glycine in spinal-cord-cultures that also shows a relationship with morphological maturity, suggests that these two amino acids may play a major role in spinal cord function.