LASER-DOPPLER EVALUATION OF SKIN REACTION IN VOLUNTEERS AFTER HISTAMINE IONTOPHORESIS

Iontophoresis was used for a non-invasive administration of the agonis t histamine. Flares and weals areas were measured after 1%, 0.01% and 0.0001% histamine solution iontophoresis (30 s, 1.4 mA/cm(2)). There w as no clear-cut correlation between area and concentration. 0.0001% hi stamine solution iontophoresis induced only a vanishing redness. When a typical weal developed (1% and 0.01% histamine), the blood perfusion was lower at histamine administration site between 10 and 40 min as c ompared to the values recorded during the same time interval in the fl are area. When the flare disappeared, the level of laser Doppler flowm etry (LDF) at the weal site still remained higher than basal values. T he higher the histamine concentration, the higher the LDF values at fl are sites. Controls indicated that only a low and transient increase i n LDF values was observed after NaCl iontophoresis (30 s, 1.4 mA/cm(2) ) and that histamine application (1%, 30 s) did not modify basal blood perfusion. Therefore, we suggest to use 1% histamine iontophoresis (3 0 s, 1.4 mA/cm(2)) to induce skin reaction to the agonist and to chara cterize the increase in skin blood perfusion using a laser Doppler vel ocimeter.