Nitric oxide red blood cell membrane permeability at high and low oxygen tension
Nitric oxide red blood cell membrane permeability at high and low oxygen tension
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DOI：
10.1016/j.niox.2006.11.002
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发表时间：
2007-03-01
影响因子：
3.9
通讯作者：
Kim-Shapiro, Daniel B.
中科院分区：
文献类型：
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作者：
Huang, Kris T.;Huang, Zhi;Kim-Shapiro, Daniel B.
红细胞(RBC)包裹在血液中的血红蛋白清除一氧化氮(NO)的速度比无细胞血红蛋白慢得多。这种减少的NO清除作用部分归因于固有的膜屏障，阻止NO通过红细胞膜扩散。公布的红细胞对NO的渗透率值在几个数量级之间变化。最近，红细胞清除NO的速率被证明依赖于红细胞压积(红细胞体积百分比)和氧分压。速率常数的差异被认为是由于氧对红细胞膜通透性的调节，但也可能是由于NO反应的双分子速率常数以及有氧和无氧血红蛋白的不同所致。在这里，我们模拟了在以前发表的实验条件下，红细胞没有清除。基于有限元的计算机程序模型受NO与氧合和脱氧血红蛋白的反应速率以及RBC NO清除率的公开值的约束。我们发现红细胞在充氧条件下对NO的通透性在4400-5100微米S(-1)之间，而在除氧条件下通透性大于64,000 pm，S-1。在缺氧的红细胞氧化时，渗透性变化10倍或更多。这些结果可能对生理学上没有输入或输出有重要的意义。(C)2006 Elsevier Inc.保留所有权利。
Red blood cell (RBC) encapsulated hemoglobin in the blood scavenges nitric oxide (NO) much more slowly than cell-free hemoglobin would. Part of this reduced NO scavenging has been attributed to an intrinsic membrane barrier to diffusion of NO through the RBC membrane. Published values for the permeability of RBCs to NO vary over several orders of magnitude. Recently, the rate that RBCs scavenge NO has been shown to depend on the hematocrit (percentage volume of RBCs) and oxygen tension. The difference in rate constants was hypothesized to be due to oxygen modulation of the RBC membrane permeability, but also could have been due to the difference in bimolecular rate constants for the reaction of NO and oxygenated vs deoxygenated hemoglobin. Here, we model NO scavenging by RBCs under previously published experimental conditions. A finite-element based computer program model is constrained by published values for the reaction rates of NO with oxygenated and deoxygenated hemoglobin as well as RBC NO scavenging rates. We find that the permeability of RBCs to NO under oxygenated conditions is between 4400 and 5100 mu m s(-1) while the permeability under deoxygenated conditions is greater than 64,000 pm, s-1. The permeability changes by a factor of 10 or more upon oxygenation of anoxic RBCs. These results may have important implications with respect to NO import or export in physiology. (c) 2006 Elsevier Inc. All rights reserved.