Antagonism of substance P induced facilitation of central neuronal activity by 2,4-dinitrophenol and depressant agents.

2,4-Dinitrophenol, pentobarbital, thiopental, methoxyflurane, and halothane more often antagonized the facilitatory effects of substance P than of acetylcholine on the activity of spinal dorsal horn neurons (of unanesthetized decerebrated and spinalized cats) as well as interpeduncular and cerebral cortical cells (of either rats anesthetized with methoxyflurane, nitrous oxide, and oxygen or 'cereveau isolé' rats). The results of the studies indicate that the excitatory effects of substance P on central neurons are extremely sensitive to anesthesia.