Rates of progesterone oxidation by rabbit liver microsomes before and after phenobarbitone treatment.
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.
D000818:Animals; D066298:In Vitro Techniques; D007700:Kinetics; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010634:Phenobarbital / Q000494:pharmacology*; D011374:Progesterone / Q000378:metabolism*; D011817:Rabbits; D013255:Steroid 21-Hydroxylase / Q000378:metabolism
D011374:Progesterone; D013255:Steroid 21-Hydroxylase; D010634:Phenobarbital