Fig. 4

Selective A-fiber nerve block experiments using Beta-Alanine (panels A), BAM 8-22 (panels B) and  Cowhage (panels C) were employed to dissect C- or A-fiber involvement in generation of itch and pain sensation. A selective A-fiber nerve block influences itch sensations only when induced by β-alanine. The first column shows the NRS ratings for itch (triangles) and pain (circles) following pruritogen injection over the course of 300 s (values are means ± SEM) during a selective A-fiber block (dark gray symbols) and control conditions (light gray symbols). The second column shows the AUC of the NRS ratings of all subjects during the A-fiber block (black circles) and without (gray triangles). Significant differences are indicated (*P < 0.05)