Fig. 4. The shift of voltage of half-maximal activation (Vmid) into the hyperpolarizing direction by all local anesthetic agents significantly increased with concentration (tested with analysis of variance; P < 0.05). ( A ) Dextrobupivacaine, ( B ) levobupivacaine, ( C ) racemic bupivacaine, ( D ) dextroropivacaine, ( E ) levoropivacaine, and ( F ) racemic mepivacaine. * Significant difference. n.s. = no significant difference.