Fig 2. Blockade effects of the subsequent first (A, B), second (C, D) and third (E, F) epidural administration of ropivacaine, both in mesylate injection and sustained release suspension form, on mechanical allodynia and heat hyperalgesia in spinal nerve ligation-induced neuropathic rats.

Peripheral neuropathy was induced by unilateral L5/L6 spinal nerve ligation and approximately 7 days later. The rats received repetitive epidural injections for 3 days and the paw withdrawal responses to mechanical and radiate heat stimuli in both the ipsilateral and contralateral hind-limbs were subsequently (with 10-min interval) measured before and 1.5, 2.5, 4, 8, and 16 hrs after epidural injection. Data are presented as means ± S.E.M. (n = 6 in each group). ^a and ^b denote statistical significance of ropivacaine sustained release suspension compared to the normal saline group and ropivacaine mesylate group, respectively (P < 0.05 by a two-way ANOVA followed by a post-hoc Student-Newman-Keuls test).