Xenon Blocks the Induction of Synaptic Long-Term Potentiation in Pain Pathways in the Rat Spinal Cord In Vivo

Justus Benrath, Christina Kempf, Michael Georgieff, J??rgen Sandk??hler
2007 Anesthesia and Analgesia  
BACKGROUND: Xenon's (Xe) mechanisms for producing anesthesia and analgesia are not fully understood. We tested the effect of Xe equilibrated in a lipid formulation or normal saline on spinal C-fiber-evoked potentials and on the induction of synaptic long-term potentiation (LTP). METHODS: C-fiber-evoked field potentials were recorded in the superficial lumbar spinal cord in response to supramaximal electrical stimulation of the sciatic nerve. Anesthesia was maintained with isoflurane in
more » ... flurane in one-third O 2 and two-thirds N 2 O. Xe equilibrated at a concentration of 600 L/mL of Lipofundin MCT 20%, (n ϭ 5) or solvent alone (n ϭ 3), and Xe equilibrated at a concentration of 100 L/mL of normal saline (n ϭ 7) or saline alone (n ϭ 7) was given IV under apnea. High-frequency stimulation of the sciatic nerve was applied 60 min after the injection of Xe-containing formulations or solvents [to induce LTP]. RESULTS: High-frequency stimulation potentiated C-fiber-evoked potentials to 156% Ϯ 14% (mean Ϯ sem) of control. Low-dose Xe in saline 0.9% blocked the induction of LTP. High-dose Xe equilibrated in MC 20% showed no additional effect when compared with the solvent, which blocked the induction of LTP. CONCLUSION: Low-dose Xe in saline 0.9% revealed no antinociceptive, but preventive, action in spinal pain pathways. From the *Klinische Abteilung fü r Anästhesie und Allgemeine Intensivmedizin B, Medizinische Universität Wien, Währinger Gü rtel 18-20, AKH, A-1090 Wien, Austria; †Institut fü r Physiologie und Pathophysiologie, Universität Heidelberg, Im Neuenheimer Feld 326, D-69120 Heidelberg; ‡Klinik fü r Anästhesiologie, Universitätsklinikum Ulm, Steinhö velstrasse 9, D-89075 Ulm, Germany; and §Zentrum fü r Hirnforschung, Abteilung fü r Neurophysiologie,
doi:10.1213/01.ane.0000250368.27822.31 pmid:17179253 fatcat:ykzdu5f3rrbh7p36bqpxxzdkzi