CYTOCHROME-P-450 IMMUNOCYTOCHEMICAL CHARACTERIZATION IN LIVER-CELLS OF RABBIT - INDUCTION WITH PHENOBARBITAL

Immunogold staining of Lowicryl embedded liver sections was used to examine the specific binding of antisera against two pulmonary isozymes (2 and 5) of constitutive form cytochrome P-450, as well as against NADPH-cytochrome P-450 reductase (R) on both untreated and phenobarbital-treated rabbits. In the cytoplasm of liver parenchymal cells, the antisera bound specifically to regions rich in agranular endoplasmic reticulum. In addition, the antibodies bound to plasma membranes in the endothelium of sinusoids and capillaries, as well as to plasma membranes and ground cytoplasm of the cells in bile ducts and interlobular veins. In the liver parenchymal cells, the labelling over the agranular endoplasmic reticulum was uniform throughout the lobule. On the contrary, the labelling over nucleus, mitochondria, granular endoplasmic reticulum and Golgi apparatus was comparable to that observed in control sections. Induction with phenobarbital apparently increased the amount of the agranular endoplasmic reticulum and consequently the total number of gold particles bound in each parenchymal cell compared to controls. In addition, phenobarbital increased the labelling density of isozyme 2 in parenchymal cells, and that of isozymes 2 and 5 in endothelial cells of sinusoids and capillaries.