Fluorescence method for the measurement of penetration and metabolism of carcinogens in mouse skin.

The present study aims at elucidating by fluorescence measurements the possibilities of the mathematical description of the processes of penetration and metabolism of carcinogenic polynuclear arenes in mouse skin. The fluorescence intensities of the topically applied benzo(a)pyrene (BaP), 10-60 nmoles of BaP in 100 microliters of acetone, were measured in the interscapular region of hairless mice during three hours. A kinetic model combining a non-steady diffusion of BaP through the stratum corneum and BaP metabolic oxidation by epidermal cells was elaborated. Both the processes were described by first-order kinetic equations. Four parameters, viz. BaP flux rate constant into the stratum corneum, BaP metabolism rate constant, BaP flux at zero time and relative fluorescence intensity at zero time, can be calculated from experimental data (fluorescence intensity-time) using the kinetic model. The above method makes it possible to study the effect of other compounds, e.g., phenolic antioxidants, on BaP metabolism rates in the in vivo system.