Shibata Masahiro, Ichioka Shigeru, Ando Joji, Togawa Tatsuo, Kamiya Akira
Department of Biomedical Engineering, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Eur J Appl Physiol. 2005 Jun;94(3):352-5. doi: 10.1007/s00421-005-1315-6. Epub 2005 Apr 7.
To study the process of O(2) transport to tissue, we investigated how capillary perfusion is controlled in response to changes in tissue O(2) levels in skeletal muscle. Capillary red blood cell (RBC) velocity and perfused capillary recruitment were measured in rabbit tenuissimus muscle at various ambient oxygen tensions (pO(2)) by intravital microscopy. Both RBC velocity and capillary recruitment significantly decreased as the pO(2) level of the suffusate was increased, and the relationship between capillary perfusion, calculated from the velocity and recruitment data, and the pO(2) level of the suffusate clearly yielded a nonlinear correlation that fitted a sigmoidal curve. Capillary perfusion dramatically decreases or increases above or below a suffusate pO(2) level of around 40 Torr, where the O(2) dissociation curve of hemoglobin changes slope. These findings support the hypothesis that microvasculature possesses an intrinsic, effective flow-control mechanism by sensing the metabolic demands of tissue, intimately related to the O(2) saturation of hemoglobin.
为研究氧气向组织的输送过程，我们调查了骨骼肌中毛细血管灌注如何响应组织氧水平变化而受到调控。通过活体显微镜，在不同环境氧张力（pO₂）下测量兔缝匠肌中的毛细血管红细胞（RBC）速度和灌注毛细血管募集情况。随着灌注液pO₂水平升高，RBC速度和毛细血管募集均显著降低，根据速度和募集数据计算得出的毛细血管灌注与灌注液pO₂水平之间的关系明显呈现出非线性相关性，拟合出一条S形曲线。在灌注液pO₂水平约40 Torr上下，毛细血管灌注会急剧下降或增加，此时血红蛋白的氧解离曲线斜率发生变化。这些发现支持了以下假设：微血管通过感知与血红蛋白氧饱和度密切相关的组织代谢需求，拥有一种内在的有效流量控制机制。
