Effects of general anesthetics on formalin-induced neurokinin 1 receptor (NK1r) internalization. Scattergram presents the percent of NK1r (+) neurons showing internalization after unilateral intraplantar formalin in the ipsilateral and contralateral lumbar (L4–L6) dorsal horn of each animal as a function of receiving pretreatment with vehicle or intraperitoneal propofol (100 mg/kg), pentobarbital (50 mg/kg), or isoflurane at 2 minimum alveolar concentration (MAC) alone or N2O (66%). As indicated, none of these treatments altered the NK1r internalization in the ipsilateral lamina I compared with saline-treated animals. #Represents a significant difference between ipsilateral and contralateral spinal dorsal horn. ISO (2) = 2 MAC of isoflurane; N2O = nitrous oxide.
