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首页> 外文期刊>American Journal of Physiology >Heme oxygenase activity in placenta: direct dependence on oxygen availability.
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Heme oxygenase activity in placenta: direct dependence on oxygen availability.

机译：胎盘中的血红素加氧酶活性：直接依赖于氧的可用性。

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摘要

Carbon monoxide (CO), which is formed endogenously from heme catalyzed by heme oxygenase (HO), is proposed to play a role in vascular control. The mRNA and protein expression of the inducible isoform of HO (HO-1) increases in response to hypoxia, and it has been assumed that HO activity also increases. This assumption requires evaluation because the catalytic activity of HO requires three molecules of O(2) for each molecule of CO formed from heme, and HO activity may be limited by O(2) availability. To test the hypothesis that low physiological O(2) concentrations limit HO activity, heme-derived CO formation by microsomal fractions of homogenates of chorionic villi of human placentas was determined after exposure to 0, 1, 5, or 21% O(2). Results revealed that HO activity was directly dependent on O(2) concentration. Thus, although hypoxia may increase HO protein and mRNA expression, there is a progressive decrease in HO activity with decreasing O(2) concentration and the dependence of HO activity on O(2) concentration is similar in chorionic villi from noninfarcted areas of preeclamptic and normotensive placenta.
机译：一氧化碳（CO）是由血红素加氧酶（HO）催化的血红素内源性形成的，被提议在血管控制中发挥作用。 HO（HO-1）的诱导型亚型的mRNA和蛋白质表达响应缺氧而增加，并且已经假定HO活性也增加。此假设需要评估，因为HO的催化活性对于每个由血红素形成的CO分子需要三个O（2）分子，并且HO活性可能受O（2）可用性的限制。为了测试低生理O（2）浓度会限制HO活性的假设，在暴露于0、1、5或21％O（2）后确定了人类胎盘绒毛绒毛匀浆的微粒体级分的血红素衍生的CO形成。 。结果表明，HO活性直接取决于O（2）浓度。因此，尽管缺氧可能会增加HO蛋白和mRNA的表达，但随着O（2）浓度的降低，HO活性会逐渐降低，绒毛膜绒毛从先兆子痫前期和非梗死区的绒毛中HO活性对O（2）浓度的依赖性相似。血压正常的胎盘。

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