PURPOSE The goal of this study was to develop a methodology to investigate the relationship between contractile function and hyperpolarized (HP) [1-13C]pyruvate metabolism in a small animal model. To achieve sufficient signal from HP 13C compounds, HP 13C MRS/MRSI has required relatively large infusion volumes relative to the total blood volume in small animal models, which may affect cardiac function. METHODS Eight female Sprague Dawley rats were imaged on a 4.7T scanner with a dual tuned 1H/13C volume coil. ECG and respiratory gated k-t spiral MRSI and an IDEAL based reconstruction to determine [1-13C]pyruvate metabolism in the myocardium. This was coupled with 1H cine MRI to determine ventricular volumes and mechanical function pre- and post-infusion of [1-13C]pyruvate. For comparison to the [1-13C]pyruvate experiments, three female Sprague Dawley rats were imaged with 1H cine MRI to determine myocardial function pre- and post-saline infusion. RESULTS We demonstrated significant changes in cardiac contractile function between pre- and post-infusion of [1-13C]pyruvate. Specifically, there was an increase in end-diastolic volume (EDV), stroke volume (SV), and ejection fraction (EF). Additionally, the ventricular vascular coupling ratio (VVCR) showed an improvement after [1-13C]pyruvate infusion, indicating increased systolic performance due to an increased arterial load. There was a moderate to strong relationship between the downstream metabolic conversion of pyruvate to bicarbonate and a strong relationship between the conversion of pyruvate to lactate and the cardiac mechanical function response. CONCLUSION The infusion of [1-13C]pyruvate resulted in demonstrable increases in contractile function which was related to pyruvate conversion to bicarbonate and lactate. The combined effects of the infusion volume and inotropic effects of pyruvate metabolism likely explains the augmentation in myocardial mechanical function seen in these experiments. Given the relationship between pyruvate metabolism and contractile function observed in this study, this methodological approach may be utilized to better understand cardiac metabolic and functional remodeling in heart disease.

中文翻译：

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在超极化 13C-丙酮酸磁共振实验中测量心脏机械功能和代谢之间的联系。


目的本研究的目的是开发一种方法来研究小动物模型中收缩功能与超极化（HP）[1-13C]丙酮酸代谢之间的关系。为了从 HP 13C 化合物获得足够的信号，HP 13C MRS/MRSI 需要相对于小动物模型的总血量而言相对较大的输注量，这可能会影响心脏功能。方法 使用双调谐 1H/13C 卷线圈的 4.7T 扫描仪对 8 只雌性 Sprague Dawley 大鼠进行成像。 ECG 和呼吸门控 kt 螺旋 MRSI 以及基于 IDEAL 的重建以确定心肌中的 [1-13C] 丙酮酸代谢。与 1H 电影 MRI 相结合，以确定[1-13C]丙酮酸输注前后的心室体积和机械功能。为了与[1-13C]丙酮酸实验进行比较，使用1H电影MRI对三只雌性Sprague Dawley大鼠进行成像，以确定盐水输注前后的心肌功能。结果我们证明了[1-13C]丙酮酸输注前后心脏收缩功能的显着变化。具体来说，舒张末期容积 (EDV)、每搏输出量 (SV) 和射血分数 (EF) 有所增加。此外，输注[1-13C]丙酮酸后心室血管耦合比（VVCR）有所改善，表明由于动脉负荷增加而导致收缩性能增加。丙酮酸向碳酸氢盐的下游代谢转化之间存在中等到强的关系，而丙酮酸向乳酸的转化与心脏机械功能反应之间存在很强的关系。结论输注[1-13C]丙酮酸导致收缩功能明显增强，这与丙酮酸转化为碳酸氢盐和乳酸有关。 输注量和丙酮酸代谢的正性肌力作用的综合作用可能解释了这些实验中观察到的心肌机械功能的增强。鉴于本研究中观察到的丙酮酸代谢与收缩功能之间的关系，这种方法可用于更好地了解心脏病中的心脏代谢和功能重塑。