Fig. 4.

Example of 2 group III muscle afferents immunostained for acid-sensing ion channel 3 (ASIC3) and transient receptor potential vanilloid types 1 and 2 (TRPV1 and TRPV2). A recovered Neurobiotin-stained (arrows) group III muscle afferent (A; green) that responded to the high-metabolite mixture was found to be immunoreactive for ASIC3 (B; blue) but not TRPV1 (C; red). Another group III muscle fiber (D) intracellularly filled with Neurobiotin (arrows) responded to cold but no other stimuli and was immunoreactive for both ASIC3 (E; blue) and TRPV2 (F; red). This particular afferent had a projection into lamina I of the SC (G) and a collateral projection into lamina V (not shown). Inset: higher magnification (×40) of the labeled central projection. Scale bars: 50 μm (A–F), 200 μm (G).