In vivo correlates of altered blood rheology
In vivo correlates of altered blood rheology
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DOI：
10.3233/bir-2008-0515
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发表时间：
2008-01-01
期刊：
影响因子：
1.1
通讯作者：
Baskurt, Oguz K.
中科院分区：
文献类型：
--
作者：
Baskurt, Oguz K.
80多年来，人们已经知道，与体外测定相比，血液在体内流动条件下表现为粘性较低的流体。Whittaker和Winton的实验是最早研究血液流变学改变的体内效应的实验之一，世纪后半叶的实验研究为体内血液动力学-血液流变学关系的复杂性提供了额外的证据。仔细的研究表明，给定血液流变学改变的影响是由实验模型的性质决定的（例如，例如，在一个实施例中，研究中的器官或组织），实验方法（e.例如，在一个实施例中，活体显微术、全器官灌注）和用于改变血液流变学的方法。此外，血管控制机制可能在血液流变学改变的血液动力学效应中起主要作用：（1）与代谢自动调节简单相关的反应，其中存在由于体内血流改变和器官/组织缺氧引起的代偿性血管舒张;（2）调节内皮功能（例如，例如，在一个实施例中，NO的产生），从而导致血管阻力的变化。已在各种实验模型中研究了改变的红细胞（RBC）聚集的体内效应。一种用于改变RBC聚集性的新技术（即，RBC聚集的内在趋势），并且已经提供了反映RBC聚集的特定效应而不受改变的悬浮相性质影响的数据。这些数据表明，血液动力学效应的大小和改变的方向都取决于RBC聚集的强度。使用同样的新技术，红细胞聚集已被证明是一个重要的决定因素，内皮功能，通过其对红细胞的轴向分布和壁剪切应力的影响。这些有些不同的发现可以通过考虑对体内流动阻力具有相反影响的各种体内血液流变学机制的贡献来解释。
It is has been known for more than 80 years that compared to in vitro determinations, blood behaves as a less viscous fluid under in vivo flow conditions. The experiments of Whittaker and Winton were among the first dealing with the in vivo effects of altered blood rheology, and experimental studies during the second half of 20th century have provided additional evidence for the complexity of in vivo hemodynamics-hemorheology relationships. Careful studies indicate that the impact of a given blood rheology alteration is determined by the properties of the experimental model (e. g., organ or tissue under investigation), experimental approach (e. g., intravital microscopy, whole organ perfusion) and method used to modify blood rheology. In addition, vascular control mechanisms may play a major role in the resulting hemodynamic effects of a hemorheological alteration: (1) a response simply related to metabolic autoregulation in which there is a compensatory vasodilation due to altered in vivo blood flow and organ/tissue hypoxia; (2) modulation of endothelial function (e. g., NO production) via altering wall shear stress, thereby leading to changes of vascular hindrance. The in vivo effects of altered red blood cell (RBC) aggregation have been investigated in various experimental models. A novel technique for modifying RBC aggregability (i.e., intrinsic tendency of RBC to aggregate) by covalent attachment of specific co-polymers has been used in some studies, and has provided data reflecting the specific effects of RBC aggregation without the influence of altered suspending phase properties. These data indicate that both the magnitude of the hemodynamic effect and the direction of the alteration depend on the intensity of RBC aggregation. Using the same novel technique, RBC aggregation has been shown to be an important determinant of endothelial function through its effects on RBC axial distribution and wall shear stress. These somewhat diverse findings can be explained by considering the contribution of various in vivo hemorheological mechanisms that have opposite effects on in vivo flow resistance.