Hypertension drives myocardial remodeling, leading to changes in structure, composition and mechanical behavior, including residual stress, which are linked to heart disease progression in a gender-specific manner. Emerging therapies are also targeting constituent-specific pathological features. All previous studies, however, have characterized remodeling in the intact tissue, rather than isolated tissue constituents, and did not include sex as a biological variable. In this study we first identified the contribution of collagen fiber network and myocytes to the myocardial residual stress/strain in Dahl-Salt sensitive rats fed with high fat diet. Then, we quantified the effect of hypertension on the remodeling of the left ventricle (LV), as well as the existence of sex-specific remodeling features. We performed mechanical tests (opening angle, ring-test) and histological analysis on isolated constituents and intact tissue of the LV. Based on the measurements from the tests, we performed a stress analysis to evaluate the residual stress distribution. Statistical analysis was performed to identify the effects of constituent isolation, elevated blood pressure, and sex of the animal on the experimental measurements and modeling results. Hypertension leads to reduced residual stress/strain in the intact tissue, isolated collagen fibers, and isolated myocytes in male and female rats. Collagen remains the largest contributor to myocardial residual stress in both normotensive and hypertensive animals. We identified sex-differences in both hypertensive and normotensive animals. We observed both constituent- and sex-specific remodeling features in the LV of an animal model of hypertension.

中文翻译：

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高脂饮食达尔盐敏感大鼠的左心室几何形状、组织成分和残余应力

高血压驱动心肌重塑，导致结构、成分和机械行为的变化，包括残余应力，这些变化以特定性别的方式与心脏病进展有关。新兴疗法也针对特定成分的病理特征。然而，所有先前的研究都描述了完整组织中的重塑，而不是孤立的组织成分，并且没有将性别作为生物学变量。在这项研究中，我们首先确定了胶原纤维网络和肌细胞对喂食高脂肪饮食的 Dahl-Salt 敏感大鼠心肌残余应力/应变的贡献。然后，我们量化了高血压对左心室 (LV) 重塑的影响，以及性别特异性重塑特征的存在。我们进行了机械测试（张角、环测试）和左室分离成分和完整组织的组织学分析。根据测试的测量结果，我们进行了应力分析以评估残余应力分布。进行统计分析以确定成分分离、血压升高和动物性别对实验测量和建模结果的影响。高血压导致雄性和雌性大鼠的完整组织、分离的胶原纤维和分离的肌细胞中的残余应力/应变减少。胶原蛋白仍然是血压正常和高血压动物心肌残余应激的最大贡献者。我们确定了高血压和血压正常动物的性别差异。我们在高血压动物模型的 LV 中观察到成分和性别特异性重塑特征。