Excitatory amino acids were tested for their ability to induce cobalt uptake in cochlear explants of spiral ganglion neurons. Explants were taken from postnatal day 5 hamsters. Compared with NMDA and quisqualate, kainic acid (KA) stimulated the greatest amount of Co2+ uptake within spiral ganglion neurons as indicated by precipitation of the Co2+ accumulation and relative optical density measurements. Both L-glutamate and KA stimulation were blocked by non-NMDA receptor antagonists kynurenate and DNQX. Nifedipine, a dihydropyridine-sensitive calcium channel blocker, also partially inhibited Co2+ uptake. These data suggest that a mixed population of NMDA and non-NMDA receptors are present. Additionally non-NMDA receptors may have a role in cochlear synaptic maturation.