Depression of nociceptive sympathetic reflexes by the intrathecal administration of midazolam.
The effect of the intrathecal administration of midazolam 0.5-1.0 mg in 1-2 ml of physiological saline solution, has been observed on responses evoked in renal sympathetic nerves by supramaximal electrical stimulation of radial and tibial nerves. In artificially ventilated dogs anaesthetized with alpha-chloralose, the intrathecal administration of midazolam caused a marked depression of reflexes evoked from the tibial nerve but had no effect on either spontaneous sympathetic activity or reflexes evoked by radial nerve stimulation. Neither the small amount (1-2 microliters) of benzyl alcohol, present as a preservative (administered intrathecally), nor midazolam 1 mg kg-1 i.v. caused any significant depression of the evoked somato--sympathetic reflexes. The effects of intrathecal midazolam were reversed by the benzodiazepine antagonists Ro 15-1788 1 mg kg-1 i.v. and Ro 15-3505 1-2 mg kg-1 i.v. but not by naloxone 2 mg i.v. It is suggested that the antinociceptive effect of locally applied midazolam could be the result of a non-opioid GABA-mediated system which may have implications in the management of pain.
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001569:Benzodiazepines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D003864:Depression, Chemical; D004285:Dogs; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D007278:Injections, Spinal; D007668:Kidney / Q000294:innervation; D008874:Midazolam; D009619:Nociceptors / Q000502:physiology*; D011826:Radial Nerve / Q000502:physiology; D012018:Reflex / Q000187:drug effects*; D013564:Sympathetic Nervous System / Q000502:physiology*; D013979:Tibial Nerve / Q000502:physiology; D013997:Time Factors
D014151:Anti-Anxiety Agents; D001569:Benzodiazepines; D008874:Midazolam