Beard Daniel A, Schenkman Kenneth A, Feigl Eric O
Department of Bioengineering, University of Washington, Box 352255, Seattle, WA 98195, USA.
Am J Physiol Heart Circ Physiol. 2003 Nov;285(5):H1826-36. doi: 10.1152/ajpheart.00380.2003. Epub 2003 Jul 17.
An anatomically realistic model for oxygen transport in cardiac tissue is introduced for analyzing data measured from isolated perfused guinea pig hearts. The model is constructed to match the microvascular anatomy of cardiac tissue based on available morphometric data. Transport in the three-dimensional system (divided into distinct microvascular, interstitial, and parenchymal spaces) is simulated. The model is used to interpret experimental data on mean cardiac tissue myoglobin saturation and to reveal differences in tissue oxygenation between buffer-perfused and red blood cell-perfused isolated hearts. Interpretation of measured mean myoglobin saturation is strongly dependent on the oxygen content of the perfusate (e.g., red blood cell-containing vs. cell-free perfusate). Model calculations match experimental values of mean tissue myoglobin saturation, measured mean myoglobin, and venous oxygen tension and can be used to predict distributions of intracellular oxygen tension. Calculations reveal that approximately 20% of the tissue is hypoxic with an oxygen tension of <0.5 mmHg when the buffer is equilibrated with 95% oxygen to give an arterial oxygen tension of over 600 mmHg. The addition of red blood cells to give a hematocrit of only 5% prevents tissue hypoxia. It is incorrect to assume that the usual buffer-perfused Langendorff heart preparation is adequately oxygenated for flows in the range of < or =10 ml. min-1. ml tissue-1.
为分析从离体灌注豚鼠心脏测得的数据，引入了一种心脏组织中氧输送的解剖学真实模型。该模型基于可用的形态测量数据构建，以匹配心脏组织的微血管解剖结构。模拟了三维系统（分为不同的微血管、间质和实质空间）中的传输。该模型用于解释关于平均心脏组织肌红蛋白饱和度的实验数据，并揭示缓冲液灌注和红细胞灌注的离体心脏之间组织氧合的差异。测量的平均肌红蛋白饱和度的解释强烈依赖于灌注液的氧含量（例如，含红细胞与无细胞灌注液）。模型计算与平均组织肌红蛋白饱和度、测量的平均肌红蛋白和静脉氧张力的实验值相匹配，可用于预测细胞内氧张力的分布。计算表明，当缓冲液与95%的氧气平衡以提供超过600 mmHg的动脉氧张力时，约20%的组织处于氧张力<0.5 mmHg的缺氧状态。添加红细胞使血细胞比容仅为5%可防止组织缺氧。假设通常的缓冲液灌注Langendorff心脏制备在流量<或=10 ml·min-1·ml组织-1范围内能充分氧合是不正确的。
