A model study of intracellular oxygen gradients in a myoglobin-containing skeletal muscle fiber.
A model study of intracellular oxygen gradients in a myoglobin-containing skeletal muscle fiber.
复制标题
含肌红蛋白的骨骼肌纤维中细胞内氧梯度的模型研究。
DOI：
10.1016/s0006-3495(86)83715-8
复制
发表时间：
1986
影响因子：
3.4
通讯作者：
Federspiel,WJ
中科院分区：
文献类型：
--
作者：
Federspiel,WJ
一个理论上的二维模型被用来研究在红色骨骼肌纤维的氧梯度。该模型描述了稳态，自由和肌红蛋白促进氧气扩散到一个呼吸圆柱形肌纤维横截面。假设肌膜处的氧张力沿着肌膜变化，作为纤维周围离散毛细血管氧供应的近似。通过考虑与最大呼吸红肌纤维相关的参数来研究最大氧梯度。该模型预测，由于离散的毛细血管源施加在肌膜的氧张力的角度变化不深入渗透到纤维肌红蛋白浓度，扩散系数，周围的毛细血管的数量，和肌膜的氧张力水平的生理值的范围内。此外，纤维芯中的氧张力由肌膜处的平均氧张力决定。然而，从纤维周边到核心的氧张力下降，确实显著依赖于肌红蛋白浓度、肌膜处的氧张力水平以及氧和肌红蛋白扩散率。通过计算最大呼吸的最小平均肌膜氧张力而不发展细胞内缺氧区域来总结这种依赖性。对于肌红蛋白丰富的肌纤维（0.5 mM肌红蛋白），该模型预测，最大耗氧量可以进行一个相对平坦的（小于5毫米汞柱）的氧张力下降，从纤维周边到核心在一个大范围内的扩散系数。
A theoretical two-dimensional model is used to investigate oxygen gradients in a red skeletal muscle fiber. The model describes the steady state, free and myoglobin-facilitated diffusion of oxygen into a respiring cylindrical muscle fiber cross section. The oxygen tension at the sarcolemma is assumed to vary along the sarcolemma as an approximation to the discrete capillary oxygen supply around the fiber. Maximal oxygen gradients are studied by considering parameters relevant to a maximally-respiring red muscle fiber. The model predicts that angular variations in the oxygen tension imposed at the sarcolemma due to the discrete capillary sources do not penetrate deeply into the fiber over a range of physiological values for myoglobin concentration, diffusion coefficients, number of surrounding capillaries, and oxygen tension level at the sarcolemma. Also, the oxygen tension in the core of the fiber is determined by the average oxygen tension at the sarcolemma. The drop in oxygen tension from fiber periphery to core, however, does depend significantly on the myoglobin concentration, the oxygen tension level at the sarcolemma, and the oxygen and myoglobin diffusivities. This dependence is summarized by calculating the minimum average sarcolemmal oxygen tension for maximal respiration without the development of an intracellular anoxic region. For a myoglobin-rich muscle fiber (0.5 mM myoglobin), the model predicts that maximal oxygen consumption can proceed with a relatively flat (less than 5 mm Hg) oxygen tension drop from fiber periphery to core over a large range for diffusion coefficients.