The effects of bupivacaine combined with different adjuvants on block onset and duration and on ion channel expressions (SCN9A, TRPM) in sciatic nerve block in rats.

BACKGROUND/AIM: The objective of this experimental study was to examine the effects of epinephrine, dexmedetomidine, and clonidine added as adjuvants to bupivacaine on block onset and effect times, as well as the effects on the Na+ and Ca+2 channel gene expressions, which may indicate cell damage in the sciatic nerve cell membrane.

MATERIALS AND METHODS: Rats were divided into five groups: Group S (sham), saline solution; Group B, bupivacaine; Group BD, bupivacaine + dexmedetomidine; Group BC, bupivacaine + clonidine; and Group BE, bupivacaine + epinephrine. For each group, 0.2 mL of local anesthetic was injected into the sciatic nerve bifurcation point of the right leg. Sensory (proprioceptive and nociceptive block) and motor block onset and ending times were recorded.

RESULTS: The shortest onset time for the examined sciatic block was observed in the BC group, whereas the longest sensory and motor block times were observed in the BD group. The present data suggest suppressed TRPM7 and increased TRPM2 in the groups other than the BE group.

CONCLUSION: Clonidine is more suitable for fast onset of peripheral nerve blocks, whereas the addition of dexmedetomidine is better in terms of duration. Because the SCN9A and TRPM2,4,7 expression ratios of the BE group showed the least amount of change, this group had the best cellular integrity.