Figure 7. Histogram of percentage maximum possible effect (MPE) for clonidine alone (diagonal line), clonidine plus U50,488H (cross-hatched line), and U50,488H alone (open box) 10 min after intrathecal administration. Each dose shown below the x-axis was administered in five to eight rats. By analysis of variance, combinations of clonidine and U50,488H at all doses tested showed no significant difference in effects as compared with the corresponding clonidine doses used alone (e.g., 5 micro gram clonidine + 50 micro gram U50,488H, 5 micro gram clonidine + 100 micro gram U50,488H, or 5 micro gram clonidine alone). Cl = clonidine; U = U50,488H.