Conrad K P, Vill M, McGuire P G, Dail W G, Davis A K
Department of Physiology, University of New Mexico School of Medicine, Albuquerque 87131.
FASEB J. 1993 Oct;7(13):1269-76. doi: 10.1096/fasebj.7.13.7691671.
The endogenous biosynthesis of nitric oxide (NO) is increased during gestation. To begin our investigation of a possible tissue source (or sources), we examined the placenta. We postulated that analogous to the endothelium of blood vessels, the syncytiotrophoblast (STr) cell layer that lines the intervillous blood space of the human placenta would express NO synthase. Our results show that human placental villi express a calcium- and calmodulin-sensitive form of NO synthase, located mainly in the microsomal cell fraction. By in situ hybridization using a riboprobe generated from human endothelial NO synthase cDNA, we observe NO synthase mRNA expression in STr. The STr also shows NADPH-diaphorase staining, indicating the presence of NO synthase, and most likely other flavin-containing enzymes involved in sex steroid metabolism. NO synthase activity was also detected in the villi of a complete mole placenta (which lacks fetal vessels), further supporting a trophoblastic origin. Our findings suggest a previously unrecognized role for STr-derived NO in placental function.
孕期一氧化氮（NO）的内源性生物合成会增加。为了开始研究可能的组织来源，我们检查了胎盘。我们推测，类似于血管内皮，人类胎盘绒毛间隙血腔内衬的合体滋养层（STr）细胞层会表达一氧化氮合酶。我们的结果表明，人胎盘绒毛表达一种对钙和钙调蛋白敏感的一氧化氮合酶形式，主要位于微粒体细胞组分中。通过使用从人内皮型一氧化氮合酶cDNA产生的核糖探针进行原位杂交，我们观察到STr中有一氧化氮合酶mRNA表达。STr也显示出NADPH-黄递酶染色，表明存在一氧化氮合酶，并且很可能存在参与性类固醇代谢的其他含黄素酶。在完全性葡萄胎胎盘（缺乏胎儿血管）的绒毛中也检测到了一氧化氮合酶活性，进一步支持了其滋养层来源。我们的研究结果表明，STr衍生的NO在胎盘功能中具有先前未被认识到的作用。
