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.