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首页> 外文期刊>American Journal of Physiology >MR tagging demonstrates quantitative differences in regional ventricular wall motion in mice, rats, and men.
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MR tagging demonstrates quantitative differences in regional ventricular wall motion in mice, rats, and men.

机译：MR标签表明小鼠，大鼠和男性的局部心室壁运动存在定量差异。

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Rats and genetically manipulated mouse models have played an important role in the exploration of molecular causes of cardiovascular diseases. However, it has not been fully investigated whether mice or rats and humans manifest similar patterns of ventricular wall motion. Although similarities in anatomy and myofiber architecture suggest that fundamental patterns of ventricular wall motion may be similar, the considerable differences in heart size, heart rate, and sarcomeric protein isoforms may yield quantitative differences in ventricular wall mechanics. To further our understanding of the basic mechanisms of myofiber contractile performance, we quantified regional and global indexes of ventricular wall motion in mice, rats, and men using magnetic resonance (MR) imaging. Both regular cine and tagged MR images at apical, midventricular, and basal levels were acquired from six male volunteers, six Fischer 344 rats, and seven C57BL/6 mice. Morphological parameters and ejection fraction were computed directly from cine images. Myocardial twist (rotation angle), torsion (net twist per unit length), circumferential strain, and normalized radial shortening were calculated by homogeneous strain analysis from tagged images. Our data show that ventricular twist was conserved among the three species, leading to a significantly smaller torsion, measured as net twist per unit length, in men. However, both circumferential strain and normalized radial shortening were the largest in male subjects. Although other parameters, such as circumferential-longitudinal shear strain, need to be evaluated, and the causes of these differences in contractile mechanics remain to be elucidated, the preservation of twist appears fundamental to cardiac function and should be considered in studies that extrapolate data from animals to humans.
机译：大鼠和转基因小鼠模型在探索心血管疾病的分子原因中起了重要作用。但是，尚未完全研究小鼠或大鼠与人是否表现出相似的心室壁运动模式。尽管解剖结构和肌纤维结构的相似性表明心室壁运动的基本模式可能相似，但心脏大小，心率和肌节蛋白同工型的显着差异可能会导致心室壁力学的定量差异。为了进一步了解肌纤维收缩表现的基本机制，我们使用磁共振（MR）成像技术对小鼠，大鼠和男性中室壁运动的区域和整体指数进行了量化。从六名男性志愿者，六只Fischer 344只大鼠和七只C57BL / 6小鼠中获得了根尖，心室中和基底水平的常规电影和标记MR图像。形态参数和射血分数直接从电影图像中计算。通过均质应变分析从标记图像中计算出心肌扭转（旋转角度），扭转（每单位长度的净扭转），周向应变和归一化径向缩短。我们的数据显示，在这三个物种中，心室扭曲得以保留，导致男性的扭曲明显变小（以每单位长度的净扭曲衡量）。然而，在男性受试者中，周向应变和归一化的径向缩短均最大。尽管还需要评估其他参数，例如周向-纵向剪切应变，并且尚需弄清这些收缩力学差异的原因，但扭转的保留似乎是心脏功能的基础，应在从数据中推断数据的研究中予以考虑对人类的动物。

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