[Epidural midazolam attenuates renal sympathetic nerve activity in rabbits]

The effects of epidural midazolam on heart rate (HR), mean arterial pressure (MAP) and the renal sympathetic nerve activity (RSNA) were examined. Under alpha-choloralose anesthesia, 31 male Japanese-white rabbits received epidural catheterization and surgical procedures for measurement of the renal sympathetic nerve activity. Epidural low (0.05%) and high (0.5%) concentrations of midazolam did not affect HR, but significantly decreased MAP and RSNA-spikes (the spike count of RSNA). Intravenous flumazenil significantly increased MAP and RSNA-spikes. These findings suggest that the decrease in RSNA-spikes induced by epidural midazolam is derived from the benzodiazepine receptor. Intramuscular midazolam (0.5%) did not affect HR, but decreased MAP and RSNA-spikes significantly. In the spinal cord dissected rabbits, epidural midazolam (0.5%) did not affect HR and MAP, but significantly attenuated RSNA-spikes. In conclusion, epidural midazolam attenuated RSNA through the benzodiazepine receptors of both the spinal and supraspinal nervous system.