Milewich L, Gant N F, Schwarz B E, Chen G T, MacDonald P C
Am J Obstet Gynecol. 1979 Mar 15;133(6):611-7. doi: 10.1016/0002-9378(79)90006-1.
The concentration of 5 alpha-pregnane-3,20-dione in peripheral blood of pregnant women is higher than that found in blood obtained from nonpregnant women throughout the luteal phase of the ovulatory cycle. The in vitro synthesis of 5 alpha-reduced pregnanes from [3H]progesterone by placental tissue was investigated using tissue minces and homogenates in the presence of added nicotinamide-adenine dinucleotide phosphate. The metabolites, [3H]5 alpha-pregnane-3,20-dione and [3H]3 beta-hydroxy-5 alpha-pregnan-20-one, were isolated and characterized employing a combination of chromatographic techniques, derivative formation, and crystallization with authentic [14C]5 alpha-pregnane-3,20-dione and [14C]3 beta-hydroxy-5 alpha-pregnan-20-one to constant 3H:14C ratios. In short-term incubations with placenta homogenates, the apparent pH optimum for the synthesis of 5 alpha-pregnane-3,20-dione was 8.8. There was no evidence for the formation of 5 beta-reduced pregnanes from [3H]progesterone by placental tissue. The in vitro metabolism of [3H]progesterone by minces of five term placentas, during 1 hour incubations at pH 7.4, was studied. The rate of formation of 5 alpha-pregnane-3,20-dione varied from 109 to 197 pmoles/gm placental tissue/hr.
孕妇外周血中5α-孕烷-3,20-二酮的浓度高于在排卵周期黄体期从非孕妇采集的血液中的浓度。使用组织碎块和匀浆，在添加烟酰胺腺嘌呤二核苷酸磷酸的情况下，研究了胎盘组织从[3H]孕酮体外合成5α-还原孕烷的情况。采用色谱技术、衍生物形成以及与真实的[14C]5α-孕烷-3,20-二酮和[14C]3β-羟基-5α-孕烷-20-酮结晶相结合的方法，分离并鉴定了代谢产物[3H]5α-孕烷-3,20-二酮和[3H]3β-羟基-5α-孕烷-20-酮，使其3H:14C比值恒定。在与胎盘匀浆的短期孵育中，合成5α-孕烷-3,20-二酮的表观最适pH为8.8。没有证据表明胎盘组织能从[3H]孕酮形成5β-还原孕烷。研究了五个足月胎盘碎块在pH 7.4下孵育1小时期间[3H]孕酮的体外代谢情况。5α-孕烷-3,20-二酮的形成速率在109至197皮摩尔/克胎盘组织/小时之间变化。
