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首页> 外文期刊>American Journal of Physiology >Duration of no-load state affects opening angle of porcine coronary arteries.
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Duration of no-load state affects opening angle of porcine coronary arteries.

机译：空载状态的持续时间影响猪冠状动脉的张开角度。

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摘要

The zero-stress state of a blood vessel has been extensively studied because it is the reference state for which all calculations of intramural stress and strain must be based. It has also been found to reflect nonuniformity in growth and remodeling in response to chemical or physical changes. The zero-stress state can be characterized by an opening angle, defined as the angle subtended by two radii connecting the midpoint of the inner wall. All prior studies documented the zero-stress state or opening angle with no regard to duration of the no-load state. Our hypotheses were that, given the viscoelastic properties of blood vessels, the zero-stress state may have "memory" of prior circumferential and axial loading, i.e., duration of the no-load state influences opening angle. To test these hypotheses, we considered ring pairs of porcine coronary arteries to examine the effect of duration in the no-load state after circumferential distension. Our results show a significant reduction in opening angle as duration of the no-load state increases, i.e., vessels that are reduced to the zero-stress state directly from the loaded state attain much larger opening angles at 30 min after the radial cut than rings that are in the no-load state for various durations. To examine the effect of axial loading, we found similar reductions in opening angle with duration in the no-load from the in situ state, albeit the effect was significantly smaller than that of circumferential loading. Hence, we found that the zero-stress state has memory of both circumferential and axial loading. These results are important for understanding viscoelastic properties of coronary arteries, interpretation of the enormous data on the opening angle and strain in the literature, and standardization of future measurements on the zero-stress state.
机译：血管的零应力状态已被广泛研究，因为它是所有壁内应力和应变计算都必须基于的参考状态。还发现它反映了响应化学或物理变化的生长和重塑的不均匀性。零应力状态的特征在于张开角度，张开角度定义为由连接内壁中点的两个半径对向的角度。所有先前的研究都记录了零应力状态或打开角度，而与空载状态的持续时间无关。我们的假设是，考虑到血管的粘弹性，零应力状态可能具有先前的圆周和轴向载荷的“记忆”，即空载状态的持续时间会影响张角。为了检验这些假设，我们考虑了成对的猪冠状动脉对，以检查周向扩张后空载状态下持续时间的影响。我们的结果表明，随着空载状态持续时间的增加，打开角度会显着减小，即，直接从加载状态减小到零应力状态的容器在径向切割后30分钟处的开角要比环大得多在各种持续时间处于空载状态。为了检查轴向载荷的影响，我们发现从原位状态开始，空载持续时间中开角的减小程度与持续时间相似，尽管其影响明显小于周向载荷。因此，我们发现零应力状态具有周向和轴向载荷的记忆。这些结果对于理解冠状动脉的粘弹特性，解释文献中关于张开角度和应变的大量数据以及对未来在零应力状态下的测量结果进行标准化具有重要意义。

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