Preparation and characterization of subcellular fractions from the liver of the Northern Pike, Esox lucius.

The present study was designed to prepare and characterize subcellular fractions from the liver of the Northern pike (Esox lucius), with special emphasis on the preparation of microsomal fractions suitable for studying xenobiotic metabolism. The purity of the different fractions obtained by differential centrifugation, as well as the recovery of different organelles, was determined using both enzyme markers and morphological examination with the electron microscope. Attempts were also made to increase the recovery of fragments of the endoplasmic reticulum in the microsomal fraction. Finally, the subcellular distribution of several drug-metabolizing enzymes (cytochrome P-450, benzpyrene monoxygenase, epoxide hydrolase and glutathione transferases) were determined. With the exception of the subcellular distribution of epoxide hydrolase, the results obtained here resemble closely those reported fo rat liver and the microsomal fraction prepared is highly suitable for further studies of drug metabolism in pike liver.