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Rates of progesterone oxidation by rabbit liver microsomes before and after phenobarbitone treatment
Abstract:
Liver sections, removed from outbred NZW rabbits under anesthesia, were used to determine the rates of progesterone oxidation prior to assessment of the effects of phenobarbitone(PB)-treatment. Progesterone 21-hydroxylase exhibited the same high affinity, low Km kinetics before and after PB-treatment, whereas the Vmax was significantly reduced. PB-treatment did not affect progesterone 21-hydroxylation by the adrenal microsomes of two groups of PB-treated and untreated rabbits. 21-Hydroxylase activity was detected for the first time with spleen microsomes but the majority of spleens examined lacked activity. 6 beta-Hydroxylation by control liver microsomes showed consistently low affinity, high Km-values and was inhibited to a lesser, inconsistent degree than 21-hydroxylation by PB-treatment.
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