Free and conjugated steroids in maternal and fetal plasma in the cow near term.
Free and conjugated steroids in maternal and fetal plasma in the cow near term.
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近期母牛和胎儿血浆中的游离类固醇和结合类固醇。
作者：
B. Hoffmann;W. C. Wagner;T. Gimenez
5例孕妇（妊娠第247 ~ 273天）通过留置导管从母体颈静脉和子宫静脉、脐动静脉和胎儿尾腔静脉采集血浆。4个胎儿在4天内死亡，第5个胎儿在手术后第3天活了下来。CPB和RIA分别测定孕酮(P)、睾酮(T)以及游离和偶联（酶水解）皮质醇(F)、皮质酮(B)、雌酮（E5）、雌二醇-17和-17′（E20、E2′）。类固醇浓度在母体和胎儿循环中表现出明显的分离。胎儿P值较低（0.20 ng/ml），但母体P值高，与妊娠阶段预期一致，而T值在所有采样点均较低（0.08 - 0.55 ng/ml）。除一头奶牛在270天后插管外，母体的皮质激素高于胎儿室，胎儿在分娩当天的4天内F从71 ng/ml增加到102 ng/ml。母体血浆F/B比值未发生显著变化，而胎儿血浆F/B比值在采样期间有所增加。结合的F和B分别占游离量的5%和10 - 20%，而结合的雌激素可以超过游离雌激素的10到100倍，在2个胎儿样本中达到100 ng E20/ml以上。游离和偶联E1是母体雌激素的主要成分，而胎儿雌激素以Esa为主。在两个隔间中发现最低浓度的E2p（游离：0.007 - 0.060 ng/ml，结合0.04 - 1.69 ng/ml，取决于采样地点）。除E2p外，根据配对样本，子宫静脉雌激素水平高于颈静脉，胎儿腔静脉雌激素水平最高，脐动脉最低。
Plasma samples were collectedin 5 pregnant cosa (between Days 247 and 273 postconception) via indwelling cathetersfrom the maternal jugular and uterine veins, umbilicalarteryand vein and the fetalvena cava caudalis.Four fetusesdied within four days and the fifthwas born aliveon Day 3 postsurgery. Progesterone (P),Testosterone (T) as wellas freeand conjugated (enzyme hydroly- sis)cortisol(F), corticosterone (B), estrone (E5), estradiol-17oand -17� (E20, E2�) were deter- mined by CPB and RIA respectively. Steroid concentrations showed a distinct separation between maternal and fetal circulation. Fetal P was low (� = 0.20 ng/ml) but maternal P was high as antici- pated for the stage of pregnancy, while T values were low in all sampling sites (0.08 - 0.55 ng/ml). Corticoids were higher in the maternal than fetal compartment except in one cow which was cannulated post Day 270 where F increased in the fetus within 4 days from 71 to 102 ng/ml on the day of parturition. No significant changes in F/B-ratios occurred in maternal samples while fetal plasma F/B ratios increased during the sampling period. Conjugated F and B were 5 percent and 10 - 20 percent of the free, respectively, while conjugated estrogens could exceed the free estro- gens by a factor of 10 to 100 reaching concentrations above 100 ng E20/ml in 2 samples in the fetus. Free and conjugated E1 was the major maternal estrogen while it was Esa in the fetus. In both compartments lowest concentrations were found for E2p (free: 0.007 - 0.060 ng/ml, con- jugated 0.04 - 1.69 ng/ml, depending on the sampling site). Except for E2p and based on paired samples, estrogen levels in the uterine vein were higher than in the jugular vein, and in the fetus they were highest in the vena cava and lowest in the umbilical artery.