Ursino M, Fabbri G, Belardinelli E
Department of Electronics, Computer Science and Systems, University of Bologna, Italy.
Cardioscience. 1992 Mar;3(1):13-25.
Arterioles and microvascular venules often show rhythmic spontaneous changes in diameter, called vasomotion. In this study, we analyze the possibility that vasomotion originates from the activity of the local myogenic mechanism. This analysis uses an original mathematical model of the peripheral circulation. The peripheral vascular bed has been represented as a series of three consecutive segments, each characterized by its value of vascular resistance per unit weight of tissue. The internal radius of the vessels in the last two segments, and hence their hydraulic resistance, has been assumed to be affected by the local myogenic response of the vascular smooth muscle. This dependence has been reproduced using the Laplace law. Both the static and dynamic (i.e. rate-dependent) components of the myogenic response have been included in the model, in accordance with recent experimental results. Simulations demonstrate that rhythmic, self-sustained oscillations can develop when the dynamic component of the myogenic response of terminal arterioles is much greater than that of more proximal microvessels. A moderate increase in arterial pressure favors the occurrence of oscillations, whereas vasodilatory stimuli tend to suppress vasomotion and contribute to the stabilization of vascular diameters.
小动脉和微血管小静脉的直径常常呈现出有节律的自发变化，称为血管运动。在本研究中，我们分析了血管运动起源于局部肌源性机制活动的可能性。该分析使用了一个外周循环的原始数学模型。外周血管床被表示为连续的三个节段，每个节段的特征是其单位组织重量的血管阻力值。假设最后两个节段血管的内半径，以及因此它们的水力阻力，受血管平滑肌局部肌源性反应的影响。这种依赖性通过拉普拉斯定律得以再现。根据最近的实验结果，模型中纳入了肌源性反应的静态和动态（即速率依赖性）成分。模拟结果表明，当终末小动脉肌源性反应的动态成分远大于更近端微血管的动态成分时，会出现有节律的、自我维持的振荡。动脉压适度升高有利于振荡的发生，而血管舒张刺激往往会抑制血管运动并有助于血管直径的稳定。
