Microdetermination of adrenocortical steroids by double isotope method. IV. Determination of corticosteroids in human placenta.

Abstract

Homogenate of the human term placenta was extracted consecutively with ethanol and methanol, and the extract was fractionated with ether-water system into free and conjugated corticosteroids. Fractions obtained by enzymic hydrolysis of conjugates and free fraction were submitted to reverse isotope dilution analysis and the kinds of corticosteroids present in each fraction were identified. Amount of these corticosteroids was determined by the double isotope derivative dilution method in which the carbonyl group in C-3 position alone is derived to thiosemicarbazone-35S. Presence of the following corticosteroids was proved per 1 g (wet weight) of human term placental tissue : 0.136-1.176μg of free and 0.014-0.099 μg of conjugated 11-deoxycorticosterone, 0.040-0.668 μg of free and 0.079-0.273 μg of conjugated 11-dehydrocorticosterone, 0.026-0.078 μg of free and 0.023-0.037 μg of conjugated corticosterone, 0.016-0.050 μg of free and 0.014-0.031 μg of conjugated cortisone, 0.004-0.045 μg of free and 0.009-0.015 μg of conjugated cortisol, and 0.014 μg of free and 0.011 μg of conjugated aldosterone, with a larger amount than the above of progesterone (0.731-2.370 μg of free and 0.235-0.964 μg of conjugated). The use of the present method of determination allows separatory determination of free and conjugated corticosteroids, using about one-half of the placenta (250-280g). Quantitative distribution of corticosteroids in three placenta analyzed here showed a marked individual difference but in all the placental tissues analyzed, the content of 11-deoxycorticosterone and 11-dehydrocorticosterone was higher than that of the three kinds of 11-oxo-17α-hydroxycorticosteroid.