TY - JOUR
T1 - Conversion of plasma progesterone to deoxycorticosterone in men, nonpregnant and pregnant women, and adrenalectomized subjects. Evidence for steroid 21-hydroxylase activity in nonadrenal tissues
AU - Winkel, C. A.
AU - Milewich, L.
AU - Parker, C. R.
AU - Gant, N. F.
AU - Simpson, E. R.
AU - MacDonald, P. C.
PY - 1980
Y1 - 1980
N2 - During the third trimester of human pregnancy the concentrations of deoxycorticosterone (DOC) in maternal plasma are 4-50 times those in nonpregnant women and men. It has been suggested that the increased amount of DOC in maternal plasma originates in the fetal compartment. We considered an alternate explanation for the high levels of DOC in plasma of near-term pregnant women, viz., that DOC may be derived in part from 21-hydroxylation of maternal plasma progesterone. To test this hypothesis we measured the fractional conversion of plasma progesterone to DOC from the relationship between the 3H:14C ratio of the infused tracers, [3H]progesterone and [14C]-DOC, and the 3H:14C ratio of urinary 3α,21-dihydroxy-5β-pregnan-20-one (tetrahydro-DOC). The fractional conversion of plasma progesterone to DOC ([ρ](P-DOC)(BU)), measured in this manner, was 0.007±0.001 (mean±SEM, n = 26) in the subjects of this study. The values for [ρ](P-DOC)(BU) varied widely among subjects (0.002-0.022) but the range of values for [ρ](P-DOC)(BU) was similar among women pregnant with an anencephalic or dead fetus, nonpregnant and adrenalectomized women, and men. The transfer constant of conversion of progesterone to DOC in plasma, [ρ](P-DOC)(BB), remained constant in a nonpregnant woman during the infusion of nonradiolabeled progesterone at rates of 0-14 mg/h. Based on the results of these studies, we conclude that DOC is formed by extra-adrenal 21-hydroxylation of plasma progesterone and that the rate of formation of DOC by this pathway is proportional to the concentration of progesterone in plasma.
AB - During the third trimester of human pregnancy the concentrations of deoxycorticosterone (DOC) in maternal plasma are 4-50 times those in nonpregnant women and men. It has been suggested that the increased amount of DOC in maternal plasma originates in the fetal compartment. We considered an alternate explanation for the high levels of DOC in plasma of near-term pregnant women, viz., that DOC may be derived in part from 21-hydroxylation of maternal plasma progesterone. To test this hypothesis we measured the fractional conversion of plasma progesterone to DOC from the relationship between the 3H:14C ratio of the infused tracers, [3H]progesterone and [14C]-DOC, and the 3H:14C ratio of urinary 3α,21-dihydroxy-5β-pregnan-20-one (tetrahydro-DOC). The fractional conversion of plasma progesterone to DOC ([ρ](P-DOC)(BU)), measured in this manner, was 0.007±0.001 (mean±SEM, n = 26) in the subjects of this study. The values for [ρ](P-DOC)(BU) varied widely among subjects (0.002-0.022) but the range of values for [ρ](P-DOC)(BU) was similar among women pregnant with an anencephalic or dead fetus, nonpregnant and adrenalectomized women, and men. The transfer constant of conversion of progesterone to DOC in plasma, [ρ](P-DOC)(BB), remained constant in a nonpregnant woman during the infusion of nonradiolabeled progesterone at rates of 0-14 mg/h. Based on the results of these studies, we conclude that DOC is formed by extra-adrenal 21-hydroxylation of plasma progesterone and that the rate of formation of DOC by this pathway is proportional to the concentration of progesterone in plasma.
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U2 - 10.1172/JCI109918
DO - 10.1172/JCI109918
M3 - Article
C2 - 6968322
AN - SCOPUS:0018886137
SN - 0021-9738
VL - 66
SP - 803
EP - 812
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 4
ER -