Fig. 3. Opioid agonist does not affect Aδ- fiber mechanosensitivity independent of preapplication of hypertonic saline. (A–C ) Rat paws were injected with 10% NaCl or 0.9% NaCl, as described in fig. 2. Responses for Aδ-mechanonociceptors to a suprathreshold mechanical stimulus were recorded in rat skin. (A ) Aδ-fiber stimulus-response plots were unchanged in 10% NaCl- compared with 0.9% injected-rat paws (n = 9 in both groups). (B, C ) Mechanically evoked responses were not significantly different in Aδ-fibers treated with [d-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAMGO) in synthetic interstitial fluid (SIF) (10 μM, blue circles ) compared with controls (SIF; red squares ) in 0.9% NaCl-injected paws (n = 9, in both groups) (B ), and 10% NaCl-injected paws (C ) (DAMGO, n = 5; SIF, n = 9) (P > 0.05, all above repeated-measures ANOVA, Bonferroni post hoc  correction). SIF = synthetic interstitial fluid.