title: Differential time courses of skin blood flow and hyperalgesia in the human sunburn reaction following ultraviolet irradiation of the skin.
abstract: The response of skin to ultraviolet (UV) irradiation is an inflammation with pronounced vasodilation and hyperalgesia. Volunteers underwent UV irradiation of patches of forearm skin 3 cm in diameter. The intensity of the UV irradiation (290-320 nm) ranged between 133 mJ/cm2 and 400 mJ/cm2. Changes in skin blood flow were measured with laser Doppler technique at 3, 6, 9, 12, 24, 30, 36, 48, 60, 72, 96 and 216 h post UV irradiation. The alteration in pain threshold was measured for heat with a Peltier thermode and for pressure with a metal stylus. The effect of repeated topical pre-treatment 4 days prior to UV irradiation with 1.5 g of 0.04% capsaicin containing ointment was also investigated.UV irradiation resulted in a dose-dependent increase of skin blood flow for more than 96 h post-irradiation. There were two peaks of blood flow at 12 h and 36 h. Topical application of capsaicin prior to UV irradiation attenuated blood flow from 30 h to 45 h post UV irradiation. Enhanced blood flow was also present 5 mm outside the irradiated area (flare reaction). The control level of heat pain threshold was 44.5+/-0.7;C in normal skin. Heat pain thresholds were lowered by up to 7.761.2;C in UV-irradiated areas in a dose-dependent fashion. The control level of pressure pain threshold was 15.260.3N. Pressure pain thresholds were lowered by up to 6 N in irradiated areas. Maximal hyperalgesia coincided with the second peak of skin blood flow between 30 h and 60 h post UV irradiation. The effects of topical application of capsaicin suggests an involvement of neuropeptide mechanisms in the late phase of the human sunburn reaction.
authors.affiliation: Klinik für Anaesthesiologie, Universität Heidelberg, Im Neuenheimer Feld 110, Heidelberg, D-69120, Germany. justus.benrath@urz.uni-heidelberg.de
authors.forename: J
authors.initials: J
authors.lastname: Benrath
authors.forename: F
authors.initials: F
authors.lastname: Gillardon
authors.forename: M
authors.initials: M
authors.lastname: Zimmermann
mesh_terms: D000328:Adult; D002211:Capsaicin / Q000494:pharmacology; D004307:Dose-Response Relationship, Radiation; D004890:Erythema / Q000503:physiopathology; D005260:Female; D006801:Humans; D006930:Hyperalgesia / Q000503:physiopathology*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D017288:Pain Threshold / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D012867:Skin / Q000098:blood supply* / Q000528:radiation effects; D013471:Sunburn / Q000503:physiopathology*; D014466:Ultraviolet Rays
chemical_list: D002211:Capsaicin