Fig. 4. Effect of intrathecal pretreatment with vehicle, BRL 44408 (α^2Asubtype-preferring antagonist, A, upper panel ), and ARC 239 (α^{2 NON-A}subtype-preferring antagonist, B, lower panel ) on the antihypersensitivity effect of intrathecal injection of 56 nmol clonidine in injured animals. Data are mean ± SD of 6–8 animals. *P < 0.05 versus  vehicle. †P < 0.05 versus  5.6-nmol dose of ARC. ‡P < 0.05 versus  baseline and time 0.