CYTOCHROME-P-450 CONTENT AND MIXED-FUNCTION OXIDATION BY MICROSOMES FROM RABBIT ALVEOLAR MACROPHAGES

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 90  (1) , 101-108
Abstract
Cytochrome P-450 content and p-nitroanisole demethylation (a mixed-function oxidation) were investigated in the microsomal fraction from rabbit alveolar macrophages. The content of cytochrome P-450 was 0.13 .+-. 0.024 (mean .+-. S.E., n = 9) nmol/mg protein and was not stimulated by chlorpromazine pretreatment. BCG pretreatment decreased cytochrome P-450-specific content, suggesting that the microsomal protein pool was diluted by de novo synthesis of noncytochrome proteins. Demethylation of p-nitroanisole by alveolar macrophage microsomes during a 1 h incubation was 17.1 .+-. 1.4 nmol .times. h-1 .times. mg protein-1. The microsomal fraction from homogenates of whole lungs had a cytochrome P-450 content of 0.32 .+-. 0.078 nmol/mg protein and p-nitroanisole demethylase activity of 26.6 .+-. 8.7 nmol .times. h-1 .times. mg protein-1. The presence of a cytochrome P-450 in rabbit alveolar macrophage microsomal fraction which can catalyze a mixed-function oxidation reaction is suggested. Comparison of alveolar macrophage and whole lung microsomal preparations indicates that alveolar macrophage cytochrome P-450 comprises a minor fraction of the total pulmonary pool.