Nitrous Oxide Induces Preemptive Analgesia in the Rat That is Antagonized by Halothane

Noxious stimulation-induced sensitization of the central nervous system has been proposed as a key element in the development of subsequent protracted pain. Accordingly, the authors used the formalin model of pain to test the hypothesis that general anesthesia can produce preemptive analgesia and thereby interfere with noxious stimulation-induced central sensitization.Rats received 0.9% or 1.8% halothane, 30% or 75% nitrous oxide (N2O), or 75%...