Figure 4

Isobologram for the coadministration of PPF and (±)-CPP at fixed-ratio combinations. The white circle on the straight line represents the point of theoretic activity calculated with a confidence limit of 95%, whereas the black circle under the straight line corresponds to the experimental point obtained with the monoarthritic rats (95% confidence limit). The experimental point was significantly different from the theoretically calculated point (mean ± SEM; ***P < 0.001, two-tailed Student t test), indicating supraadditive synergy in the Randall-Selitto test.