Abstract
Summary
Rat liver homogenate was separated into nuclei, mitochondria, microsomes and supernatant fractions by differential centrifugation. The homogenate, the fractions and combinations of fractions were studied for their ability to decrease the activity of estradiol, estrone or diethylstilbestrol when incubated at 38°C for 2 hours in the presence of DPN and nicotinamide. The uteri of ovariectomized mice were used to determine the amount of biological activity remaining.
No single fraction decreased the activity of estradiol markedly. The microsomes and supernatant, when recombined, were comparable to homogenate in inactivating this hormone.
Though the homogenate of kidney or salivary glands was inert in this respect, the supernatant of either tissue when combined with liver microsomes effectively inactivated estradiol. The supernatant could also be replaced by riboflavin monophosphate (RMP). The microsomes of kidney or of salivary glands when used with liver supernatant failed to inactivate estradiol. The inactivation of estrone occurred with the same liver fractions necessary for estradiol: microsomes and supernatant. No appreciable inactivation occurred with any single fraction. For the in vitro inactivation of diethylstilbestrol, liver supernatant alone was almost as effective as homogenate. Kidney supernatant was ineffective. RMP alone, in the absence of any tissue, destroyed the estrogenic activity of diethylstilbestrol. A non-enzymatic inactivation of this hormone by liver tissue was also indicated.
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