[Inhibitory action of dopamine on excitatory transmission in the isolated spinal cord of the rat]

Abstract

The effect of dopamine on the ventral root potential evoked by single supramaximal dorsal root stimulation was studied in the experiment in the isolated superfused spinal cord of 10-16 days old rats. It was discovered that application of dopamine caused the reversible dose-dependent inhibition of the mono- and polysynaptic ventral root reflex responses. The minimal effective concentration was 1 X 10(-8) mol/l. Dopamine applied in concentrations of 1 X 10(-4) mol/l and 1 X 10(-3) mol/l decreased the amplitude of the monosynaptic ventral root potential by 20% and 87% as against the control, respectively. Under the same conditions the amplitude of the polysynaptic ventral root potential decreased by 18% and 87% as against the control, respectively. The obtained results demonstrate that the dopaminergic brainstem-spinal pathways take part in the control of the transmission in the segmentary reflex arc.