Presynaptic, high-affinity glutamate uptake in excitatory neuromuscular junctions of the retractor unguis muscle of the locust: determination of the Km value using high resolution autoradiography.

Using high resolution autoradiography the Km of the presynaptic, Na+-dependent and aspartate inhibited, high affinity glutamate uptake in insect neuromuscular junctions was determined. The values found (approx. 15 microM) did not differ for the glia and terminal axons. This Km value agrees with those values determined by classical biochemical techniques for presynaptic high affinity uptake systems in insect neuromuscular junctions and glutamatergic central nervous systems.