Blood pressure-induced physiological strain variability modulates wall structure and function in aorta rings.
Blood pressure-induced physiological strain variability modulates wall structure and function in aorta rings.
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DOI：
10.1088/1361-6579/aae65f
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发表时间：
2018-10-30
影响因子：
3.2
通讯作者：
Suki B
中科院分区：
文献类型：
--
作者：
Imsirovic J;Bartolák-Suki E;Jawde SB;Parameswaran H;Suki B
血管平滑肌细胞通过重组其细胞骨架和收缩成分来响应机械拉伸。最近，我们发现，当大鼠主动脉环暴露于4小时的周期性应变生理变异性（称为可变拉伸（VS））时，大鼠主动脉环的收缩力保持不变，模拟搏动血压变异性。然而，当主动脉暴露于单调拉伸（MS）时，收缩性降低，其振幅等于VS的平均峰值应变。在这里，我们重新分析数据以获得壁刚度，并添加新的组织学和抑制剂研究来测试VS对细胞外基质的影响。结果表明，虽然在4小时MS或VS期间主动脉的刚度没有变化，但MS后力学行为的非线性略强。抑制剂研究还表明，线粒体能量产生和细胞骨架组织参与了这种波动驱动的机械转导。通过免疫组织化学标记图像量化的平滑肌层β-肌动蛋白重组与收缩过程中的收缩力相关。血管壁结构的组织学分析提供了MS后弹性蛋白和胶原纤维重组的证据，而vs后则较少。结果表明，MS肌肉收缩的丧失被纤维结构重组所补偿，导致与vs相似的壁刚度。我们得出结论，拉伸变异性调节的肌张力在维持主动脉壁结构和机械稳态中起作用，对血管状况有影响血压变异性的以血压变异性丧失或增加为特征的
Vascular smooth muscle cells respond to mechanical stretch by reorganizing their cytoskeletal and contractile elements. Recently, we showed that contractile forces in rat aorta rings were maintained when the rings were exposed to 4 h of physiological variability in cycle-by-cycle strain, called variable stretch (VS), mimicking beat-to-beat blood pressure variability. Contractility, however, was reduced when the aorta was exposed to monotonous stretch (MS) with an amplitude equal to the mean peak strain of VS. Here we reanalyzed the data to obtain wall stiffness as well as added new histologic and inhibitor studies to test the effects of VS on the extracellular matrix. The results demonstrate that while the stiffness of the aorta did not change during 4 h MS or VS, nonlinearity in mechanical behavior was slightly stronger following MS. The inhibitor studies also showed that mitochondrial energy production and cytoskeletal organization were involved in this fluctuation-driven mechanotransduction. Reorganization of β-actin in the smooth muscle layer quantified from immunohistochemically labeled images correlated with contractile forces during contraction. Histologic analysis of wall structure provided evidence of reorganization of elastin and collagen fibers following MS but less so following VS. The results suggested that the loss of muscle contraction in MS was compensated by reorganization of fiber structure leading to similar wall stiffness as in VS. We conclude that muscle tone modulated by variability in stretch plays a role in maintaining aortic wall structural and mechanical homeostasis with implications for vascular conditions characterized by a loss or an increase in blood pressure variability.