Nitric oxide uptake by erythrocytes is primarily limited by extracellular diffusion not membrane resistance
Nitric oxide uptake by erythrocytes is primarily limited by extracellular diffusion not membrane resistance
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DOI：
10.1074/jbc.m201939200
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发表时间：
2002-07-19
影响因子：
4.8
通讯作者：
Zweier, JL
中科院分区：
文献类型：
--
作者：
Liu, XP;Samouilov, A;Zweier, JL
NO进入红细胞(RBC)的过程具有重要的生物学意义，因为它调节内皮源性NO的生物利用度和扩散距离。据报道，红细胞内NO与氧合血红蛋白(Hb)的反应速度比同等数量的游离氧合血红蛋白的反应速度慢近三个数量级。与早期关于红细胞吸氧的研究一致，据报道，细胞外扩散过程解释了红细胞包裹的Hb(Liu，X.，Miller，M.J.，Joshi，M.S.，Sadowska-Krowicka，H.，Clark，D.A.和Lancaster，J.R.，Jr.)对NO的低吸收。(1998)J.Biol.化学。273、18709-18713)。然而，后来有人提出，红细胞膜提供了对NO摄取的主要阻力，而不是细胞外扩散过程(Vaughn，M.W.，Huang，K.T.，Kuo，L.和Liao，J.C.(2000)J.Biol)。化学。275、2342-2348)。这一结论是基于竞争实验，该实验假定能够确定红细胞摄取NO的速率常数，而不受细胞外扩散的限制。为了检验这一假设的有效性，我们对竞赛实验进行了理论分析。在这里，我们证明了竞争实验并没有消除细胞外扩散的限制。对竞争数据的模拟表明，红细胞摄取NO的主要阻力是由细胞外扩散造成的，而不是由红细胞膜引起的。这种细胞外扩散阻力负责防止内皮细胞内NO信号的干扰，而不需要细胞内血红蛋白特殊的NO摄取或独特的膜阻力机制。
The process of NO transfer into erythrocytes (RBCs) is of critical biological importance because it regulates the bioavailability and diffusional distance of endothelial-derived NO. It has been reported that the rate of NO reaction with oxyhemoglobin (Hb) within RBCs is nearly three orders of magnitude slower than that by equal amounts of free oxyhemoglobin. Consistent with early studies on oxygen uptake by RBCs, the process of extracellular diffusion was reported to explain this much lower NO uptake by RBC encapsulated Hb (Liu, X., Miller, M. J., Joshi, M. S., Sadowska-Krowicka, H., Clark, D. A., and Lancaster, J. R., Jr. (1998) J. Biol. Chem. 273, 18709-18713). However, it was subsequently proposed that the RBC membrane provides the main resistance to NO uptake rather than the process of extracellular diffusion (Vaughn, M. W., Huang, K. T., Kuo, L., and Liao, J. C. (2000) J. Biol. Chem. 275, 2342-2348). This conclusion was based on competition experiments that were assumed to be able to determine the rate constant of NO uptake by RBCs without extracelluar diffusion limitation. To test the validity of this hypothesis, we theoretically analyzed competition experiments. Here, we show that competition experiments do not eliminate the extracellular diffusion limitation. Simulation of the competition data indicates that the main resistance to NO uptake by RBCs is caused by extracellular diffusion in the unstirred layer surrounding each RBC but not by the RBC membrane. This extracellular diffusion resistance is responsible for preventing interference of NO signaling in the endothelium without the need for special NO uptake by intracellular hemoglobin or a unique membrane resistance mechanism.