Red blood cells (RBCs) are vital for transporting oxygen from the lungs to the body’s tissues through the intricate circulatory system. They achieve this by binding and releasing oxygen molecules to the abundant hemoglobin within their cytosol. The volume of RBCs affects the amount of oxygen they can carry, yet whether this volume is optimal for transporting oxygen through the circulatory system remains an open question. This study explores, through high-fidelity numerical simulations, the impact of RBC volume on advective oxygen transport efficiency through arterioles, which form the area of greatest flow resistance in the circulatory system. The results show that, strikingly, RBCs with volumes similar to those found in vivo are most efficient to transport oxygen through arterioles. The flow resistance is related to the cell-free layer thickness, which is influenced by the shape and the motion of the RBCs: at low volumes, RBCs deform and fold, while at high volumes, RBCs collide and follow more diffuse trajectories. In contrast, RBCs with a healthy volume maximize the cell-free layer thickness, resulting in a more efficient advective transport of oxygen.

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健康红细胞的体积最适合小动脉中平流氧输送

红细胞 (RBC) 对于通过复杂的循环系统将氧气从肺部输送到身体组织至关重要。它们通过将氧分子与胞质内丰富的血红蛋白结合和释放来实现这一目标。红细胞的体积会影响它们可以携带的氧气量，但这个体积是否最适合通过循环系统输送氧气仍然是一个悬而未决的问题。这项研究通过高保真度数值模​​拟，探讨了红细胞体积对小动脉平流氧输送效率的影响，小动脉形成了循环系统中流动阻力最大的区域。令人惊讶的是，结果表明，体积与体内相似的红细胞通过小动脉输送氧气的效率最高。流动阻力与无细胞层厚度有关，而无细胞层厚度受红细胞形状和运动的影响：在低体积时，红细胞变形和折叠，而在高体积时，红细胞碰撞并遵循更分散的轨迹。相比之下，具有健康体积的红细胞可以最大化无细胞层厚度，从而实现更有效的氧气平流运输。