Perineural capsaicin treatment attenuates reactive hyperaemia in the rat skin

The neural mechanisms of reactive cutaneous hyperaemia were studied by using a novel experimental approach: the simultaneous measurement of cutaneous blood flow by laser-Doppler flowmetry in adjacent innervated and chemodenervated skin regions of the rat hindpaw served by the same artery. Transient occlusion of the femoral artery (0.5-6 min) resulted in reactive hyperaemia that was greatly reduced in the chemodenervated region. After 3 min arterial occlusion, peak cutaneous blood flow was 109 +/- 13% vs. 53 +/- 7%* (% change from baseline, n = 11, *P < 0.05), and the total hyperaemic response was 110 +/- 21 vs. 52 +/- 12* (arbitrary perfusion units) in intact vs. chemodenervated skin regions, respectively. The findings provide clear evidence for the involvement of peptidergic capsaicin-sensitive afferent nerves in the mechanism of reactive cutaneous hyperaemia. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.