Actions of Glutamate on Dissociated Mammalian Spinal Neurons in vitro

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Abstract
The culture of dissociated spinal cord cells of the fetal mouse provides accessibility for electrophysiological analysis of the action of glutamate on these cells. The present study re-evaluates the glutamate reversal potential by means of independent microelectrodes for current injection and potential measurement. Anomalous rectification was prominent in 11 of 19 spinal cord neurons investigated. The mean glutamate reversal potential found by extrapolation in six of the eight remaining cells was –22.8 mV, while two cells yielded clearly different values (+2 mV in both cases). Observations on the bursts of synaptic potentials which sometimes accompany glutamate depolarizations yielded new evidence in support of an excitatory action of glutamate on presynaptic terminals. When glutamate reversal potentials were estimated for different points of glutamate application on the same neuron, it was found that the value obtained could be markedly influenced by the presynaptic action of glutamate.