PHARMACOLOGICAL STUDIES ON CUTANEOUS INFLAMMATION-INDUCED BY ULTRAVIOLET-IRRADIATION .1. QUANTIFICATION OF ERYTHEMA BY REFLECTANCE COLORIMETRY AND CORRELATION WITH CUTANEOUS BLOOD-FLOW

This study was conducted to quantify the intensity of ultraviolet (UV) erythema in guinea pigs, a method for evaluating anti-inflammatory dr ugs, and to clarify any correlation of erythema with cutaneous blood f low. Skin color and cutaneous blood flow in non-administered and indom ethacin-administered animals were measured by a colorimeter and a lase r Doppler flowmeter over time after UV-irradiation treatment. Skin col or was indicated by a XYZ colorimetric system and La*b* color space. In either colorimetric system, the values of two indices, x and y or a and b*, increased along with the intensification of erythema. The in crease in the chroma (C) value calculated from a* and b* was UV-dose- dependent. This value was significantly suppressed by indomethacin 0.5 - 4 hr after irradiation, and it was found to be a clear and sensitiv e index for evaluating the suppressive effect of drugs. Cutaneous bloo d flow also increased with UV irradiation. Indomethacin significantly suppressed this increase 2 - 3 hr after UV irradiation. The changes of cutaneous blood flow correlated with those of C. These results sugge sted C was a suitable parameter to quantify UV erythema, and the chan ge of skin color in UV erythema reflected the change of cutaneous bloo d flow.