Pries A R, Secomb T W, Gaehtgens P
Deutsches Herzzentrum Berlin, D-13353 Berlin, Germany.
Am J Physiol. 1998 Aug;275(2):H349-60. doi: 10.1152/ajpheart.1998.275.2.H349.
A theoretical model was developed to simulate long-term changes of vessel diameters during structural adaptation of microvascular networks in response to tissue needs. The diameter of each vascular segment was assumed to change with time in response to four local stimuli: endothelial wall shear stress (tauw), intravascular pressure (P), a flow-dependent metabolic stimulus (M), and a stimulus conducted from distal to proximal segments along vascular walls (C). Increases in tauw, M, or C or decreases in P were assumed to stimulate diameter increases. Hemodynamic quantities were estimated using a mathematical model of network flow. Simulations were continued until equilibrium states were reached in which the stimuli were in balance. Predictions were compared with data from intravital microscopy of the rat mesentery, including topological position, diameter, length, and flow velocity for each segment of complete networks. Stable equilibrium states, with realistic distributions of velocities and diameters, were achieved only when all four stimuli were included. According to the model, responses to tauw and P ensure that diameters are smaller in peripheral than in proximal segments and are larger in venules than in corresponding arterioles, whereas M prevents collapse of networks to single pathways and C suppresses generation of large proximal shunts.
建立了一个理论模型，以模拟微血管网络在结构适应组织需求过程中血管直径的长期变化。假定每个血管段的直径随时间变化，以响应四种局部刺激：内皮壁面剪应力（tauw）、血管内压力（P）、流量依赖性代谢刺激（M）以及沿血管壁从远端到近端段传导的刺激（C）。假定tauw、M或C的增加或P的降低会刺激直径增加。使用网络流动的数学模型估计血流动力学量。持续进行模拟，直到达到刺激平衡的平衡状态。将预测结果与大鼠肠系膜活体显微镜检查的数据进行比较，包括完整网络各段的拓扑位置、直径、长度和流速。只有当所有四种刺激都包括在内时，才能实现具有现实速度和直径分布的稳定平衡状态。根据该模型，对tauw和P的响应确保外周段的直径小于近端段，且小静脉的直径大于相应小动脉，而M可防止网络塌陷为单一通路，C可抑制近端大分流的产生。
