RESISTANCE TO BLOOD-FLOW IN MICROVESSELS IN-VIVO
RESISTANCE TO BLOOD-FLOW IN MICROVESSELS IN-VIVO
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DOI：
10.1161/01.res.75.5.904
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发表时间：
1994-11-01
影响因子：
20.1
通讯作者：
GAEHTGENS, P
中科院分区：
文献类型：
--
作者：
PRIES, AR;SECOMB, TW;GAEHTGENS, P
通过外周血管床的血流阻力强烈影响心血管功能和向组织的运输。对于给定的血管结构，血流阻力由流经微血管的血液的流变性决定。提出了一种计算血液流变学对微血管流动阻力贡献的新方法。在活体显微镜下，测定了大鼠肠系膜微循环终末网络的所有血管节段(多达913个)的形态(直径和长度)、血流速度、红细胞压积和拓扑位置。血流速度和红细胞压积也从数学陶氏模拟中预测，其中假定阻力如何与直径、红细胞压积和剪切率的关系进行了优化，以最大限度地减少实测值和预测值之间的偏差。对于直径小于约40微米的微血管，由此产生的流动阻力明显更高，并且与先前通过测量狭窄玻璃管中的血液流动而估计的红细胞压积有更强的相关性。例如，在正常红细胞压积下，10微米微血管的流动阻力被发现比相应的玻璃管的流动阻力高出约4倍。在单独的实验中，通过直接测量总压降和体积流量来估计微血管网络的流动阻力，在系统血细胞比容故意从0.08到0.68的情况下。结果与基于上述优化阻力的预测非常吻合，但与基于草管数据的预测不一致。微小微血管中出人意料的高流动阻力可能与血液成分与血管内表面之间的相互作用有关，这在光管中是不存在的。
Resistance to blood flow through peripheral vascular beds strongly influences cardiovascular function and transport to tissue. For a given Vascular architecture, flow resistance is determined by the rheological behavior of blood flowing through microvessels. A new approach for calculating the contribution of blood theology to microvascular flow resistance is presented. Morphology (diameter and length), flow velocity, hematocrit, and topological position were determined for all vessel segments (up to 913) of terminal microcirculatory networks in the rat mesentery by intravital microscopy. Flow velocity and hematocrit were also predicted from mathematical dow simulations, in which the assumed dependence of how resistance on diameter, hematocrit, and shear rate was optimized to minimize the deviation between measured and predicted values. For microvessels with diameters below approximate to 40 mu m, the resulting flow resistances are markedly higher and show a stronger dependence on hematocrit than previously estimated from measurements of blood flow in narrow glass tubes. For example, flow resistance in 10-mu m microvessels at normal hematocrit is found to exceed that of a corresponding glass tube by a factor of approximate to 4. In separate experiments, flow resistance of microvascular networks was estimated from direct measurements of total pressure drop and volume flow, at systemic hematocrits intentionally Varied from 0.08 to 0.68. The results agree closely with predictions based on the above-optimized resistance but not with predictions based on grass-tube data. The unexpectedly high flow resistance in small microvessels may be related to interactions between blood components and the inner vessel surface that do not occur in smooth-walled tubes.