Effect of pentazocine on the evoked potentials recorded in the primary somesthetic cortical areas of guinea pigs.

The influence of pentazocine on the evoked potentials registered in the primary somesthetic cortical area in guinea pigs under pentobarbital anesthesia was studied. The stimulation was applied in the contralateral lip and the evoked cortical responses from different zones on the cortex stereotaxically localized were registered. Pentazocine (5-10 mg/kg i.v.) induced a significant increase in the latency of the evoked potentials as compared with controls. Since morphine does not modify these potentials, the effect of pentazocine is interpreted as being a direct one on the primary pain pathway.