BACKGROUND Red blood cell (RBC) deformability may increase, or decrease, following application of shear stress ("shear conditioning"), depending upon the specific magnitude and duration of exposure. However, the time course of altered RBC deformability following shear remains unresolved. OBJECTIVE We utilised shear conditioning known to increase (10 Pa) or decrease (64 Pa) RBC deformability and subsequently rested the cells; serial measurements of deformability during the rest period facilitated defining the time course of recoverability. A second experiment repeated the shear conditioning and recovery period to explore whether multiple duty-cycles augmented the response following the initial exposure. METHODS Shear conditioning was performed for 300 s at the desired shear stress. Ektacytometry was used to quantify human RBC deformability immediately and during rest (3, 5, 60, 120, 240, 300 s) using discrete samples. RBC were shear conditioned twice in a separate experiment, with 300 s rest separating the conditioning. RESULTS Shear conditioning at 10 Pa induced increased cell deformability by 19.5 ± 0.3%, which reduced to 7.2 ± 0.4% after 300 s of rest. Shear conditioning at 64 Pa decreased cell deformability by 30.5 ± 13.9%, and after 300 s rest, remained decreased (19.3 ± 9.4%) compared with baseline. The second duty-cycle augmented initial responses induced by shear conditioning. CONCLUSION Specific shear conditioning results in either temporarily increased cell deformability, or a less reversible decrease of RBC deformability.

中文翻译：

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暴露于剪切后红细胞变形能力的恢复时间过程取决于条件剪切应力。

背景技术取决于暴露的具体幅度和持续时间，在施加切应力（“剪切调节”）之后，红细胞（RBC）的可变形性可以增加或减少。然而，剪切后红细胞变形能力改变的时间过程仍未解决。目的我们利用剪切调节来提高（10 Pa）或降低（64 Pa）RBC的可变形性，并随后使细胞静止。在休息期间进行可变形性的系列测量有助于确定可恢复性的时间过程。第二个实验重复了剪切条件和恢复期，以探索在初始暴露后多个占空比是否会增强响应。方法在所需的剪切应力下进行300 s的剪切调节。使用细胞计数法立即使用离散样本在休息期间（3、5、60、120、240、300 s）定量人类RBC的可变形性。在单独的实验中对RBC进行了两次剪切调理，其余300 s分开了调理。结果在10 Pa的剪切条件下，细胞变形能力提高了19.5±0.3％，在静止300 s后降低到7.2±0.4％。在64 Pa的剪切条件下，细胞变形能力降低了30.5±13.9％，并且在休息300 s后，与基线相比仍降低了（19.3±9.4％）。第二个占空比增加了由剪切条件引起的初始响应。结论特定的剪切条件导致细胞变形能力暂时增加，或RBC变形能力的可逆性降低。在单独的实验中对RBC进行了两次剪切调理，其余300 s分开了调理。结果在10 Pa的剪切条件下，细胞变形能力提高了19.5±0.3％，在静止300 s后降低到7.2±0.4％。在64 Pa的剪切条件下，细胞变形能力降低了30.5±13.9％，并且在休息300 s后，与基线相比仍降低了（19.3±9.4％）。第二个占空比增加了由剪切条件引起的初始响应。结论特定的剪切条件导致细胞变形能力暂时增加，或RBC变形能力的可逆性降低。在单独的实验中对RBC进行了两次剪切调理，其余300 s分开了调理。结果在10 Pa的剪切条件下，细胞变形能力提高了19.5±0.3％，在静止300 s后降低到7.2±0.4％。在64 Pa的剪切条件下，细胞变形能力降低了30.5±13.9％，并且在休息300 s后，与基线相比仍降低了（19.3±9.4％）。第二个占空比增加了由剪切条件引起的初始响应。结论特定的剪切条件导致细胞变形能力暂时增加，或RBC变形能力的可逆性降低。休息300秒钟后为4％。在64 Pa的剪切条件下，细胞变形能力降低了30.5±13.9％，并且在休息300 s后，与基线相比仍降低了（19.3±9.4％）。第二个占空比增加了由剪切条件引起的初始响应。结论特定的剪切条件导致细胞变形能力暂时增加，或RBC变形能力的可逆性降低。休息300秒钟后为4％。在64 Pa的剪切条件下，细胞变形能力降低了30.5±13.9％，并且在休息300 s后，与基线相比仍降低了（19.3±9.4％）。第二个占空比增加了由剪切条件引起的初始响应。结论特定的剪切条件导致细胞变形能力暂时增加，或RBC变形能力的可逆性降低。