Rinker K D, Prabhakar V, Truskey G A
Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA.
Biophys J. 2001 Apr;80(4):1722-32. doi: 10.1016/S0006-3495(01)76143-7.
In this study we examined whether monocytic cell attachment to vascular endothelium was affected by elevating shear stress at a constant shear rate. Contact time, which is inversely related to the shear rate, was fixed and viscosity elevated with dextran to increase the shear stress (and hence the net force on the cell) independently of shear rate. At a fixed contact time, tethering frequencies increased, rolling velocities decreased, and median arrest durations increased with increasing shear stress. Rolling and short arrests (< 0.2 s) were well fit by a single exponential consistent with adhesion via the formation of a single additional bond. The cell dissociation constant, k(off), increased when the shear stress was elevated at constant shear rate. Firmly adherent cells arresting for at least 0.2 s were well fit by a stochastic model involving dissociation from multiple bonds. Therefore, at a fixed contact time and increasing shear stress, bonds formed more frequently for rolling cells resulting in more short arrests, and more bonds formed for firmly arresting cells resulting in longer arrest durations. Possible mechanisms for this increased adhesion include greater monocyte deformation and/or more frequent penetration of microvilli through steric and charge barriers.
在本研究中，我们检测了在恒定剪切速率下提高剪切应力是否会影响单核细胞与血管内皮的黏附。与剪切速率成反比的接触时间固定不变，通过右旋糖酐提高黏度以独立于剪切速率增加剪切应力（从而增加作用于细胞的净力）。在固定的接触时间下，随着剪切应力增加，系留频率升高，滚动速度降低，中位滞留时间延长。滚动和短暂滞留（<0.2秒）通过与经由形成单个额外键的黏附一致的单指数很好地拟合。当在恒定剪切速率下提高剪切应力时，细胞解离常数k(off)增加。通过涉及从多个键解离的随机模型能很好地拟合至少滞留0.2秒的牢固黏附细胞。因此，在固定的接触时间和增加的剪切应力下，滚动细胞形成键的频率更高，导致更多短暂滞留，而牢固滞留细胞形成更多键，导致更长的滞留时间。这种黏附增加的可能机制包括单核细胞更大程度的变形和/或微绒毛更频繁地穿过空间和电荷屏障。
