PULMONARY ENDOTHELIAL TRANSPLASMA MEMBRANE ELECTRON TRANSPORT

肺内皮细胞进行多种代谢 调节之前静脉血的组成的过程 进入全身动脉循环。其中包括激活 和血管活性物质的失活以及氧化和 血液成分的减少。一种机制，通过它 内皮细胞影响血液成分的氧化还原状态 肺组织内的电子传递系统(还原酶) 转移还原等效物的内皮细胞质膜 从细胞内的供体到细胞外的电子受体。这个 激励正在进行的研究的假设 ESR中心是跨质膜电子传递是 参与血液中抗氧化剂成分的再生 肺毒素如百草枯的氧化还原循环。其中一个标准就是 跨质膜电子的假定电子受体 转运体是指，在将接受者添加到一个超分支之后 肺内皮细胞，受体减少的证据 可以在细胞外培养液中找到。百草枯被选为我们的 与ESR中心合作进行的初步研究，因为ESR 此前已有研究使用百草枯和 内皮细胞。在牛肺动脉中加入百草枯 内皮细胞生长在微载体珠子上，混合物是 在37度的温度下孵化。加入百草枯约60分钟后 自由基自旋陷阱5，5-二甲基-1-吡咯啉-N-氧化物(DMPO) 对内皮细胞来说，这一信号表明自由基的存在 在细胞培养上清液中观察到DMPO的捕获。一个实质上 在细胞孵育过程中观察到较低的信号强度 在没有百草枯的情况下，单独使用DMPO。这些数据表明， 百草枯被细胞还原为百草枯自由基 百草枯自由基与分子氧发生反应。由此产生的氧气 自由基产物被DMPO捕获，捕获的自由基是 在细胞外培养液中检测到。因此，这些研究表明 用EPR研究跨质膜作用的可行性 百草枯内皮细胞氧化还原循环中的电子传递 细胞。

The pulmonary endothelium carries out a variety of metabolic precesses that modulate the composition of venous blood before it enters the systemic arterial circulation. These include activation and inactivation of vasoactive substances and the oxidation and reduction of blood constituents. One mechanism by which the endothelium influences the redox status of blood constituents involves electron transport systems (reductases) within the pulmonary endothelial cell plasma membrane that transfer reducing equivalents from intracellular donors to extracellular electron acceptors. The hypothesis motivating the studies that are being carried out in the ESR Center is that trans-plasma membrane electron transport is involved in regeneration of antioxidant components of the blood and redox cycling of pulmonary toxins such as paraquat. One criterion for putative electron acceptors for the transplasma membrane electron transporters is that, after addition of the acceptor to a su spen sion of pulmonary endothelial cells, evidence of reduction of the acceptor can be found in the extracellular medium. Paraquat was chosen for our initial studies in collaboration with the ESR Center because ESR studies have previously been carried out using paraquat and endothelial cells. Paraquat was added to bovine pulmonary artery endothelial cells grown on microcarrier beads, and the mixture was incubated at 37 degrees. About 60 minutes after addition of paraquat and the free radical spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) to endothelial cells, the signal indicating the presence of a radical trapped by DMPO was observed in the cell supernatant. A substantially lower intensity signal was observed when the cells were incubated with DMPO alone, in the absence of paraquat. These data show that the paraquat was reduced to the paraquat radical by the cells and that the paraquat radical reacted with molecular oxygen. The resulting oxygen radical products were trapped by the DMPO, and the trapped radical was detected in the extracellular medium. Thus, these studies demonstrate the feasibility of using EPR to study the role of transplasma membrane electron transport in the redox cycling of paraquat by endothelial cells.