Mouse epidermal aryl hydrocarbon hydroxylase

Mouse skin contains a NADPH dependent, aryl hydrocarbon hydroxylase (AHH), which is inducible by polycyclic aromatic hydrocarbons. In general, unsubstituted polycyclic hydrocarbons caused a greater induction of epidermal AHH than substituted ones (1,2,3,4 dibenzanthracene > 1,2,5,6 dibenzanthracene > benz [a]anthracene ≥ 3 methylcholanthrene > > 7,12 dimethylbenz[a]anthracene) which did not correlate with their ability to initiate tumors in mouse skin. Two different techniques were used to isolate epidermis and similar results were obtained with both. However, the technique of isolating epidermis using a mild heat treatment required that the temperature be maintained at 52°C for 30 sec. If the temperature was raised to 54°C or above, there was a large reduction in the AHH activity. Isolated epidermis has 4 to 5 times the AHH activity as dermis and about twice that of whole skin. This was true for control mice in which AHH was induced by pretreatment with benz[a]anthracene.