Department of Physiology, Akdeniz University, Antalya, Turkey.
Clin Hemorheol Microcirc. 2010;45(2-4):169-75. doi: 10.3233/CH-2010-1293.
Previous reports have demonstrated that red blood cells (RBC) have an active nitric oxide (NO) synthesizing mechanism which has properties similar to endothelial nitric oxide synthase (eNOS). This red cell NOS activity contributes to the NO export from RBC. The present study explored the influence of shear stress applied to RBC on NO concentrations of cell suspensions. RBC were exposed to shear stress by filtration through 5 microm diameter pores under 10 cm H2O pressure, generating a wall shear stress of approximately 110Pa. NO concentration in the RBC suspensions were measured using electrochemical NO probes before and after filtration through the micropores. NO concentration was found to be significantly increased after a single passage of RBC suspensions through the micropores. The increment in NO concentration depended on the presence of calcium, being 21.8+/-4.4 nM with 1 mM calcium and 13.7+/-2.7 nM without added calcium. Including the calcium chelator EDTA completely abolished this increase. The increment of NO was also affected by the level of oxygenation, being more pronounced under hypoxic conditions. These results confirm that RBC NO generating mechanisms can be stimulated by exposing red cells to shear stress and that calcium plays a role in this stimulation.
先前的报告已经表明，红细胞（RBC）具有一种活跃的一氧化氮（NO）合成机制，其性质类似于内皮型一氧化氮合酶（eNOS）。这种红细胞NOS 活性有助于从 RBC 中输出 NO。本研究探讨了施加于 RBC 的切应力对细胞悬浮液中 NO 浓度的影响。通过在 10cmH2O 压力下过滤 5μm 直径的孔，使 RBC 暴露于切应力下，从而产生约 110Pa 的壁切应力。在通过微孔过滤之前和之后，使用电化学 NO 探针测量 RBC 悬浮液中的 NO 浓度。发现 NO 浓度在 RBC 悬浮液单次通过微孔后显著增加。NO 浓度的增加取决于钙的存在，在 1mM 钙存在下为 21.8+/-4.4nM，在没有添加钙的情况下为 13.7+/-2.7nM。包括钙螯合剂 EDTA 完全消除了这种增加。NO 的增加也受到氧合水平的影响，在缺氧条件下更为明显。这些结果证实，通过使红细胞暴露于切应力，可以刺激 RBC 的 NO 生成机制，并且钙在此刺激中发挥作用。
