Watts Tim, Barigou Mostafa, Nash Gerard B
Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
School of Chemical Engineering, College of Engineering and Physical Sciences, University of Birmingham, Birmingham, UK.
Biorheology. 2015;52(5-6):391-404. doi: 10.3233/BIR-15043.
Leukocytes and platelets typically fulfil their functions through adhesion to the walls of vessels with different size, haematocrit and shear rate.
We aimed to investigate differential effects of these variables on leukocyte and platelet adhesion.
Blood with varying haematocrit was perfused at a range of wall shear rates through capillaries of depth 100 or 300 µm coated with P-selectin or collagen.
Adhesion of leukocytes was much more efficient in the smaller capillaries, but was equal on the upper and lower surfaces and showed nearly identical shear rate dependence for either size of vessel. Platelets also adhered more efficiently in the smaller vessels (although the effect of size was not so great), and equally on upper and lower surfaces, but their adhesion was much less sensitive to increasing shear rate. In previous studies using vertically-orientated capillaries, leukocyte adhesion increased with increasing haematocrit (Am. J. Physiol.285 (2003), H229-H240). Here, in horizontal 100 µm capillaries, leukocyte adhesion was highly efficient at haematocrit of 10% but restricted to the lower surface. Adhesion decreased initially as haematocrit was increased to 30% and then increased slightly again at 40% haematocrit. Increasing haematocrit supported a monotonic increase in platelet adhesion in the horizontal capillaries.
Platelets adhere efficiently over a wider range of sizes and shear rates, and at high haematocrit. Leukocytes adhere better in smaller vessels and at low haematocrit in horizontal vessels. The different behaviours may represent 'rheological adaptation' to functions in inflammation vs. haemostasis.
白细胞和血小板通常通过黏附于具有不同尺寸、血细胞比容和剪切速率的血管壁来履行其功能。
我们旨在研究这些变量对白细胞和血小板黏附的不同影响。
将具有不同血细胞比容的血液在一系列壁面剪切速率下灌注通过深度为100或300μm且包被有P-选择素或胶原蛋白的毛细血管。
白细胞在较小的毛细血管中的黏附效率更高，但在上表面和下表面的黏附情况相同，并且对于任何一种尺寸的血管，其黏附对剪切速率的依赖性几乎相同。血小板在较小的血管中也黏附得更有效（尽管尺寸的影响没有那么大），并且在上表面和下表面的黏附情况相同，但其黏附对剪切速率增加的敏感性要低得多。在先前使用垂直取向毛细血管的研究中，白细胞黏附随着血细胞比容的增加而增加（《美国生理学杂志》285 (2003), H229 - H240）。在此，在水平的100μm毛细血管中，白细胞在血细胞比容为10%时黏附效率很高，但仅限于下表面。随着血细胞比容增加到30%，黏附最初减少，然后在血细胞比容为40%时再次略有增加。在水平毛细血管中，血细胞比容的增加支持血小板黏附呈单调增加。
血小板在更广泛的尺寸、剪切速率范围以及高血细胞比容下都能有效黏附。白细胞在较小的血管中以及水平血管中低血细胞比容时黏附得更好。这些不同的行为可能代表了对炎症与止血功能的“流变学适应”。
