UVAI-induced Edema and Pyrimidine Dimers in Murine Skin¶

The induction of edema and pyrimidine dimers in epidermal DNA was determined in the skin of SKH:HR1 mice exposed to graded doses of ultraviolet radiation AI (UVAI; 340-400 nm). Exposure to UVAI induced 1.6 +/- 0.08 x 10(-6) (mean +/- standard error of mean) pyrimidine dimers per 10(8) Da of DNA per J/m2. Edema in irradiated animals was determined as an increase in skinfold thickness. A dose of 1.8 x 10(6) J/m2 of UVAI that resulted in a 50% increase in skinfold thickness (SFT50%) would have induced 1.0 x 10(5) dimers per basal cell genome. A similar increase in SFT induced by full spectrum solar ultraviolet radiation (290-400 nm) would accompany the induction of 11.0 x 10(5) pyrimidine dimers per basal cell genome. These results support a hypothesis that UVAI-induced pathological changes of the skin are mediated through the formation of nondimer photoproducts.