Stability of cytochrome P4501A-associated enzyme activity in cryogenically stored teleost liver samples

Induction of cytochrome P4501A (CYP1A), more specifically the associated enzyme activity aryl hydrocarbon hydroxylase (AHH), has been shown to be one of the most sensitive measures of exposure of vertebrate animals to a range of organic chemical contaminants. However, in order to reliably use this biochemical method for analyzing archived samples, the stability of the enzyme activity in storage must be ascertained. Stability of AHH activity was determined for both tissue sections and subcellular fractions of liver collected from English sole (Pleuronectes vetulus), and held in cryogenic storage for up to 24 months. Our overall recommendations for sample collection, handling, storage, and assay are given.