Effects of excitatory and inhibitory amino acid agonists and antagonists on ventral horn cells in slices of spinal cord isolated from adult rats

Excitatory amino acid agonists increased the probability of discharge of ventral horn cells in slices of spinal cord isolated from adult rats. The order of potency for the facilitatory action was kainate > quisqualate > (NMDA) > -glutamate > -aspartate. (±)-2-Amino-5-phosphonovalerate (2-APV) markedly reduced the facilitatory effects produced by -aspartate and NMDA, and slightly decreased the effect produced by -glutamate but did not alter the effect of kainate. Inhibitory amino acid agonists decreased the probability of cell discharge. The order of potency for the inhibitory action was (−)-baclofen > muscimol > GLYCINE = GABA. The effects produced by glycine, muscimol or GABA and (−)-baclofen were selectively reduced by strychnine, bicuculline and phaclofen, respectively. This type of preparation may be useful for in vitro pharmacological studies on the action of transmitters and drugs on ventral horn cells in the adult spinal cord.