Aryl ether O-dealkylase activity in the skin of untreated mice in vitro.

1. O-Dealkylation of p-nitroanisole and p-nitrophenetole in 10 000 g supernatant preparations of mouse skin is detectable and quantifiable. The reaction is NADPH-dependent and is mediated by cytochrome P-450. 2. The rate of p-nitroanisole O-demethylation in mouse skin preparations is 2% of that in mouse liver preparations on a mg protein basis, but only 0.23% on a g of tissue basis. 3. For p-nitrophenetole O-deethylation, the cutaneous Vmax is 3.8% of the hepatic Vmax on a mg protein basis. The Km values for the reaction in these two tissues are in a 3:1 ratio, suggesting that there are no marked qualitative differences between cutaneous and hepatic cytochrome P-450.