Common Heart Failure With Preserved Ejection Fraction Animal Models Yield Disparate Myofibril Mechanics.
Common Heart Failure With Preserved Ejection Fraction Animal Models Yield Disparate Myofibril Mechanics.
复制标题
具有保留射血分数的常见心力衰竭动物模型会产生不同的肌原纤维力学。
DOI：
10.1161/jaha.123.032037
复制
发表时间：
2024
影响因子：
5.4
通讯作者：
Cammarato,Anthony
中科院分区：
文献类型：
--
作者：
Fenwick,AxelJ;Jani,VivekP;Foster,DBrian;Sharp,ThomasE;Goodchild,TraciT;LaPenna,Kyle;Doiron,JakeE;Lefer,DavidJ;Hill,JosephA;Kass,DavidA;Cammarato,Anthony
射血分数保留性心力衰竭（HFpEF）是一种复杂的多器官综合征。心脏损害包括舒张硬化和松弛受损、静息收缩功能正常但收缩储备下降以及中度肥大。1尽管舒张功能障碍仍然是HFpEF的基准，但肌原纤维（肌细胞的收缩细胞器）在多大程度上促成了这种行为仍不清楚。HFpEF动物模型过去强调高血压和心室肥大以实现舒张功能障碍，最近由于肥胖和糖尿病越来越普遍而将其合并。流行的啮齿动物模型包括Zucker肥胖/自发性高血压大鼠2和给予高脂饮食（HFD）和组成型NO合酶抑制剂Nω硝基l精氨酸甲酯（NAME）（HFD+ NAME）的小鼠。3然而，这两种模型都没有在HFpEF患者中观察到的舒张期疾病严重。在喂食HFD并用醋酸脱氧皮质酮（DOCA）处理以诱导容量保留/高血压的较大哥廷根小型猪中实现了舒张期病理学升高。4虽然每个模型都表现出总尺度的舒张功能障碍，尽管程度不同，但还没有关于肌原纤维机械激活和舒张特性的数据报道。因此，目前尚不清楚在模型中观察到的整体器官水平舒张功能障碍的机制基础是否涉及常见的潜在肌原纤维缺陷。这一点已经变得突出，因为新的药物正在靶向肌梅里克蛋白来治疗这类疾病。因此，为了测试是否存在亚细胞力学中的共有缺陷，从而潜在地促成腔室水平病理生理学，我们解析了来自每个HFpEF动物模型及其相应对照的单个肌原纤维的收缩和舒张的动力学参数。这些模型都是在独立的实验室中产生的，都有心室舒张充盈压升高，射血分数正常范围，心肌肥大和纤维化，以及肥胖伴葡萄糖耐受不良。2-4遵循的程序符合说明性指南。将来自每个模型组和对照组的心脏组织切片并在硝基中冷冻。将冷冻的左心室组织条在4 ℃下在4%triton皮肤溶液中孵育过夜，然后均质化以产生肌原纤维的浓缩悬浮液。细胞水平测量不能时间分辨弛豫动力学，因为即使在单个透化心肌细胞中，钙扩散也太慢而不能实现这一点。然而，由于它们的小直径，肌原纤维迅速与浴液平衡，而没有显著的扩散约束。将5个单独的肌原纤维静电拴系在连接到压电长度控制器的玻璃探针和已知刚度（0.031N/m）的玻璃悬臂之间。肌节长度从平均值设定为2.1 μm
Heart failure with preserved ejection fraction (HFpEF) is a complex, multiorgan syndrome. Cardiac man ifestations include diastolic stiffening and impaired relaxation, normal resting systolic function but de pressed systolic reserve, and modest hypertrophy. 1 Although diastolic dysfunction remains a benchmark of HFpEF, the extent to which myofibrils, the contrac tile organelles of myocytes, contribute to this behavior remains unknown. HFpEF animal models historically emphasized hypertension and ventricular hypertrophy to achieve diastolic dysfunction, and recently have in corporated obesity and diabetes as they are increas ingly prevalent. Popular rodent models include Zucker obese/spontaneously hypertensive rats 2 and mice given a high fat diet (HFD) and the constitutive NO synthase inhibitor, Nω nitro l arginine methyl ester (ʟ NAME)(HFD+ ʟ NAME). 3 However, neither model de veloped diastolic disease as severe as that observed in patients with HFpEF. Heightened diastolic pathology was achieved in larger Göttingen minipigs fed a HFD and treated with desoxycorticosterone acetate (DOCA) to induce volume retention/hypertension. 4 Although each model exhibited gross scale diastolic dysfunction, albeit to different extents, there are no data yet reported from myofibrils on their mechanical activation and relax ation properties. Thus, it remains unclear whether the mechanistic basis of global, organ level diastolic impair ments observed among the models involves common underlying myofibrillar deficiencies. This has become salient as newer pharmaceuticals are targeting sarco meric proteins to treat such diseases. Therefore, to test if shared defects in subcellular mechanics exist, and thereby potentially contribute to chamber level patho physiology, we resolved the kinetic parameters of con traction and relaxation of individual myofibrils from each HFpEF animal model and its respective control. The models, generated in independent laboratories, all had elevated ventricular diastolic filling pressure, normal range ejection fraction, myocardial hypertrophy and fibrosis, and obesity with glucose intolerance. 2–4 Procedures followed were in accordance with institu tional guidelines. Heart tissue from each model and control group was sectioned and frozen in liquid nitro gen. Frozen left ventricle tissue strips were incubated in a 4% triton skinning solution overnight at 4 C and then homogenized to produce a concentrated suspension of myofibrils. Cell level measurements cannot time resolve relaxation kinetics, as even in single permea bilized cardiomyocytes, calcium diffusion is too slow to achieve this. However, given their small diameter, myofibrils promptly equilibrate with bathing solutions without significant diffusional constraints. 5 Individual myofibrils were electrostatically tethered between a glass probe connected to a Piezo length controller and a glass cantilever of known stiffness (0.031 N/m). Sarcomere length was set to 2.1 μm from an average