Remote intrathecal morphine preconditioning is ineffective in the presence of neuraxial blockade with lidocaine

Remote intrathecal morphine preconditioning (RMPC) induces cardioprotection via a neural pathway. Intrathecal lidocaine (LID) blocks spinal cord nerve transmission. This study examine whether LID prevents the effects of RMPC. Anesthetized, open chest, male Sprague-Dawley rats were assigned to one of seven treatment groups 3 days after intrathecal catheter placement. Rats from both RMPC and LID groups, respectively, received intrathecal morphine (3 mu g/kg) and lidocaine (1%, 10 mu L); morphine was administered by three cycles of 5-minute infusions interspersed with 5-minute infusion-free periods. The LID + RMPC group received the combination of LID and RMPC. Intrathecal naloxone methiodide (NM) (20 mu g/kg) was administered either 15 minutes before RMPC, or 5 minutes before LID + RMPC. Ischemia and reperfusion injury were then induced by 30 minutes of left coronary artery occlusion, followed by 120 minutes of reperfusion. Infarct size, as a percentage of the area at risk (AAR), was determined by 2,3,5-triphenyltetrazolium staining. The RMPC and LID groups markedly reduced the infarct size (IS) compared with controls. LID prevented the effect of RMPC. NM had no effect on control and LID + RMPC treatments. However, NM pretreatment reversed cardioprotection of RMPC treatment. Intrathecal morphine preconditioning is ineffective in the presence of neuraxial blockade with lidocaine. Copyright (C) 2013, Kaohsiung Medical University. Published by Elsevier Taiwan LLC. All rights reserved.