Reflex control of the cutaneous circulation after acute and chronic local capsaicin

• Published in: Journal of applied physiology (1985) 2001-05, Vol.90 (5), p.1860-1864
• Main Authors: Charkoudian, Nisha, Fromy, Berengere, Saumet, Jean-Louis
• Format: Article
• Language: English
• Subjects: Administration, Topical; Adult; Biological and medical sciences; Body Temperature; Capsaicin - administration & dosage; Capsaicin - pharmacology; Circulatory system; Drug Administration Schedule; Female; Fundamental and applied biological sciences. Psychology; Hemodynamics. Rheology; Hot Temperature; Humans; Male; Neurons; Ointments; Regional Blood Flow - drug effects; Regional Blood Flow - physiology; Scientific imaging; Skin; Skin - blood supply; Temperature; Vasodilation - drug effects; Vasodilation - physiology; Vertebrates: cardiovascular system
• ISSN: 8750-7587; 1522-1601
• DOI: 10.1152/jappl.2001.90.5.1860

Laboratoire de Physiologie et d'Explorations Fonctionnelles Vasculaires Université d'Angers, 49045 Angers, France To investigate whether local activity of capsaicin-sensitive sensory afferents in the skin has a modulatory role in the reflex cutaneous vasodilator response to hyperthermia in humans, experiments were conducted in two parts. First, low-dose topical capsaicin (0.025%) was administered acutely to stimulate local activity of these afferents. Second, we temporarily desensitized these nerves in a small area of skin using chronic capsaicin treatment (0.075% for 7 days). Each intervention was followed by whole body heating using water-perfused suits and then by local warming to 42°C for assessment of maximum cutaneous vascular conductance. Skin blood flow was measured by laser-Doppler flowmetry and divided by mean arterial pressure (Finapres) for assessment of cutaneous vascular conductance. Maximum vascular conductance was not influenced by either acute or chronic capsaicin treatment ( P  > 0.10). After acute capsaicin, baseline cutaneous vascular conductance was elevated above that at control sites (25.34 ± 6.25 vs. 10.57 ± 2.42%max; P   0.10). Furthermore, neither acute (control: 112.74 ± 36.83 vs. acute capsaicin: 96.92 ± 28.92%max/°C; P  > 0.10) nor chronic (control: 142.45 ± 61.89 vs. chronic capsaicin: 132.12 ± 52.60%max/°C; P   > 0.10) capsaicin administration influenced the sensitivity of the reflex cutaneous vasodilator response. We conclude that local activity of capsaicin-sensitive afferents in the skin does not modify reflex cutaneous vasodilation during hyperthermia. regional blood flow; skin; vasodilation; laser-Doppler flowmetry; body temperature regulation; afferent neurons