Antonov P, Antonova M, Nikolova N, Antonova N, Vlaskovska M, Kasakov L
Specialized Hospital for Active Treatment of Cardiovascular Diseases, Department of Cardiac Rehabilitation, Bankya, Sofia, Bulgaria.
Clin Hemorheol Microcirc. 2008;39(1-4):63-8.
Viscoelastic characteristics (VEC) of old rat aorta (Wistar, 10 months) were obtained by sinusoidal excitation of intraluminal pressure (p) in cylindrical arterial preparations. The pressure excitation frequency (f(exc)) was swept in the range 3-30 Hz up and down at several mean-pressure levels while response volume oscillations were recorded and resonance curves were plotted. Natural frequency (f(0)), dynamic modulus of elasticity (E') and coefficient of viscosity (beta) were estimated from resonance curves and the dependences of VEC on p were drawn. The results showed that f(0) decreased linearly with p whereas our previous data for young rat aorta (Wistar, 4 months) showed independence of f(0) on p. E' increased nonlinearly with p with the values being higher in comparison to young rat aorta. This means stiffening of rat aorta with age in accordance with the known literature data. beta-values increased linearly with p being higher in comparison to young rat aorta, demonstrative of raised intrinsic friction in the wall. VEC values were higher at decreasing f(exc) suggesting that the direction of excitation sweeping also determines the arterial wall biomechanical behaviour. It could be concluded that blood vessels VEC worsen with age, which endangers the arterial wall integrity, especially at higher intraluminal pressure.
通过对圆柱形动脉标本进行腔内压力（p）的正弦激励，获得了老年大鼠主动脉（Wistar，10个月）的粘弹性特征（VEC）。在几个平均压力水平下，压力激励频率（f(exc)）在3 - 30 Hz范围内上下扫描，同时记录响应体积振荡并绘制共振曲线。从共振曲线估计固有频率（f(0)）、动态弹性模量（E'）和粘度系数（β），并绘制VEC对p的依赖性。结果表明，f(0)随p呈线性下降，而我们之前关于年轻大鼠主动脉（Wistar，4个月）的数据显示f(0)与p无关。E'随p呈非线性增加，其值比年轻大鼠主动脉更高。这意味着大鼠主动脉随年龄增长而变硬，这与已知的文献数据一致。β值随p呈线性增加，比年轻大鼠主动脉更高，表明血管壁内固有摩擦力增加。在f(exc)降低时VEC值更高，这表明激励扫描方向也决定了动脉壁的生物力学行为。可以得出结论，血管VEC随年龄恶化，这危及动脉壁完整性，尤其是在较高腔内压力时。
