Effects of intravenous baclofen on dorsal horn neurons of spinal cats.

Intravenous baclofen (1 mg/kg) abolished or severely attenuated the high threshold late component (but not the low threshold early component of long duration (greater than 150 msec) discharges evoked in cat dorsal horn neurons by intense transcutaneous electrical stimulation. Baclofen similarly reduced the spontaneous activities and discharges evoked by intra-arterial bradykinin in these same cells. These powerful inhibitions of dorsal horn interneurons may be the basis of baclofen's reported analgesic actions and could contribute to depression in reflex excitability of motoneurons.