Figure 4. Time-effect curves for various mixtures of lidocaine (lido) and ouabain (oua) in tail-flick tests. In contrast to 200 [micro sign]g lidocaine and 1.0 [micro sign]g ouabain, the concomitant administration of the drugs did not produce a significant prolongation of tail-flick latency. Each point represents the mean +/− SD from five or six rats.