Differential sensitivity of selected rat brain areas to excitatory neurotransmitters released by K+ depolarization

The depolarization of brain slices by high K+ concentrations in the presence of Ca2+ ions leads to the release from nerve terminals of endogenous excitatory neurotransmitters that interact with subsynaptic receptors controlling the neuronal membrane permeability to Na+ ions. This interaction has been studied by following the K+-evoked Ca2+-dependent 22Na+ efflux from 22Na+-preloaded slices from the cortex, striatum, hippocampus, cerebellum, substantia nigra and hypothalamus of the rat. The results indicate that the so-called N-methyl-D-aspartate receptor mediates the bulk of the excitatory transactions in the cortex and striatum whereas a subsynaptic glutamate receptor may mediate those in the hippocampus and cerebellum.