K(+)- and transmitter-induced rises in [Ca2+]i in auditory neurones of developing rats.

Ca2+ ions are thought to play important roles in processes underlying neuronal plasticity such as synapse stabilization. We employed the Fura-2 technique on brainstem slices of neonatal rats to measure changes in intracellular Ca2+ ([Ca2+]i) in neurons of the lateral superior olive (LSO) in order to analyse whether these cells have functional Ca2+ channels when synaptic maturation takes place. Rises in intracellular Ca2+ could be induced by KCl-evoked depolarizations or by glutamate, but not by glycine or GABA. These results show that Ca2+ channels are present in developing LSO neurones and that many of them, if not all, belong to the voltage-sensitive type. We speculate that these channels play a role during ontogeny by mediating Ca(2+)-dependent mechanisms of synapse stabilization.