Fig. 5. The presence of persistent inflammation alone is sufficient to delay recovery of mechanical threshold when rats are anesthetized with pentobarbital. Mechanical threshold was assessed with an electronic von Frey device, as described in Materials and Methods, in the hind paw ipsilateral to the site of complete Freund adjuvant (CFA) injection. There was no manipulation of the inflamed hind paw in the anesthetized group during the 3-h period of anesthesia. Changes in mechanical threshold after CFA injection were analyzed with a two-way, repeated measures ANOVA. This analysis revealed a significant (P < 0.01) influence of time and a significant influence of anesthetic (P = 0.01), with no significant interaction between the two (A ). Pooled 50% recovery of baseline mechanical threshold data from pentobarbital (Pento) and inflamed only groups are plotted as median (solid line ), with the 25th and 75th percentiles defined by the box and 5th and 95th percentiles defined by the error bars. A single outlier is indicated by the single point. Data were analyzed with a Mann–Whitney rank sum test, revealing a significant (**P < 0.01) difference between groups (B ).