Aortic stiffness is lower when PVAT is included: a novel ex vivo mechanics study
Aortic stiffness is lower when PVAT is included: a novel ex vivo mechanics study
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DOI：
10.1152/ajpheart.00574.2021
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发表时间：
2022-06-01
影响因子：
4.8
通讯作者：
Roccabianca，Sara
中科院分区：
文献类型：
--
作者：
Tuttle，Tyler;Darios，Emma;Roccabianca，Sara
血管周围脂肪组织（PVAT）越来越被认为是功能性血管系统的重要层，负责产生血管活性物质并协助动脉应激松弛。在这里，我们验证了PVAT降低主动脉僵硬的假设。我们的模型是雄性Sprague-Dawley大鼠的胸主动脉。对三组组织进行单轴力学试验：附着PVAT （+PVAT）或移除（- PVAT）的主动脉，以及分离的PVAT（仅PVAT）。力学试验的输出以柯西应力-拉伸曲线的形式报告。这项工作提出了一种新颖的，生理学相关的方法来测量离体PVAT的机械刚度。测量了低应力刚度（E0）、高应力刚度（E1）和拉伸1.2时对应的应力（σ1.2）作为膨胀率指标。低应力刚度在- PVAT样品中最大，在仅PVAT样品中最小。与+PVAT样品相比，- PVAT样品的高应力刚度和1.2拉伸应力均显著高于+PVAT样品。综上所述，这些结果表明，与+PVAT样品相比，- PVAT样品在低应力（不显著）和高应力（显著）下都更硬（更不容易膨胀）。这些结论得到了连续介质力学材料模型结果的支持，我们也用它来解释相同的实验数据。因此，当将PVAT视为主动脉壁的一部分时，组织刚度明显降低。因此，PVAT应被视为改善主动脉僵硬度升高疾病（包括高血压）血管功能的靶点。我们介绍了一种新的和生理学相关的测量血管周围脂肪组织（PVAT）机械刚度的方法，该方法表明PVAT的低，但可测量的刚度与组织内存在的胶原纤维的量线性相关。在测量主动脉壁的力学行为时包括PVAT是很重要的，它通过降低主动脉硬度而显著影响测量结果。
Perivascular adipose tissue (PVAT) is increasingly recognized as an essential layer of the functional vasculature, being responsible for producing vasoactive substances and assisting arterial stress relaxation. Here, we test the hypothesis that PVAT reduces aortic stiffness. Our model was the thoracic aorta of the male Sprague–Dawley rat. Uniaxial mechanical tests for three groups of tissue were performed: aorta with PVAT attached (+PVAT) or removed (−PVAT), and isolated PVAT (PVAT only). The output of the mechanical test is reported in the form of a Cauchy stress-stretch curve. This work presents a novel, physiologically relevant approach to measure mechanical stiffness ex vivo in isolated PVAT. Low-stress stiffness (E0), high-stress stiffness (E1), and the stress corresponding to a stretch of 1.2 (σ1.2) were measured as metrics of distensibility. The low-stress stiffness was largest in the −PVAT samples and smallest in PVAT only samples. Both the high-stress stiffness and the stress at 1.2 stretch were significantly higher in −PVAT samples when compared with +PVAT samples. Taken together, these results suggest that −PVAT samples are stiffer (less distensible) both at low stress (not significant) as well as at high stress (significant) when compared with +PVAT samples. These conclusions are supported by the results of the continuum mechanics material model that we also used to interpret the same experimental data. Thus, tissue stiffness is significantly lower when considering PVAT as part of the aortic wall. As such, PVAT should be considered as a target for improving vascular function in diseases with elevated aortic stiffness, including hypertension.NEW & NOTEWORTHYWe introduce a novel and physiologically relevant way of measuring perivascular adipose tissue (PVAT) mechanical stiffness which shows that PVAT’s low, yet measurable, stiffness is linearly correlated with the amount of collagen fibers present within the tissue. Including PVAT in the measurement of the aortic wall’s mechanical behavior is important, and it significantly affects the resulting metrics by decreasing aortic stiffness.