Grunewald W A, Sowa W
Pflugers Arch. 1978 Apr 25;374(1):57-66. doi: 10.1007/BF00585697.
The structural inhomogeneity of the myocardial capillary bed is stimulated by microcirculatory units (MCU's) in a diffusion model. This stimulation is based on MCU's in which the arrangement of the capillary ends (concurrent structure, partial and total countercurrent (structure, helical structure) as well as the structure and supply parameters are varied. The variation of these parameters is based on own measurements of the intracapillary HbO2 saturation as well as on the following parameters from the literature: frequency distribution of capillary distance and capillary radius, mean capillary length or capillary section length respectively, arterial and mean venous PO2, mean coronary blood flow, mean O2 consumption and diffusion conductivity. The analysis of O2 supply of the normoxic rat heart shows that an O2 diffusion shunt is obligatory except of MCU's with an extremely large capillary distance or with a concurrent capillary structure. Therefore the minimal tissue PO2 lies at the level of the capillary venous PO2 of a MCU. The maximum of the total PO2 frequency distribution in the normoxic rat myocardium lies at 25 +/- 5 mm Hg, i.e. above the mean venous PO2 (20 mm Hg). Tissue PO2 values between 0 and 5 mm Hg amount to 0.5% i.e. they are extremely rare. Tissue PO2 values of 0-1 mm Hg represent less than 0.2%.
在一个扩散模型中，微循环单元（MCU）刺激心肌毛细血管床的结构不均匀性。这种刺激基于MCU，其中毛细血管末端的排列（并行结构、部分和完全逆流结构、螺旋结构）以及结构和供应参数是变化的。这些参数的变化基于对毛细血管内血红蛋白氧饱和度的自身测量以及文献中的以下参数：毛细血管距离和毛细血管半径的频率分布、平均毛细血管长度或毛细血管段长度、动脉和平均静脉血氧分压、平均冠状动脉血流量、平均耗氧量和扩散传导率。对正常氧合大鼠心脏的氧气供应分析表明，除了具有极大毛细血管距离或并行毛细血管结构的MCU外，氧气扩散分流是必然存在的。因此，最低组织血氧分压处于MCU的毛细血管静脉血氧分压水平。正常氧合大鼠心肌中总血氧分压频率分布的最大值位于25±5毫米汞柱，即高于平均静脉血氧分压（20毫米汞柱）。0至5毫米汞柱之间的组织血氧分压值占0.5%，即极为罕见。0至1毫米汞柱的组织血氧分压值占比小于0.2%。
