MAGNETIC RESONANCE OF CARDIAC 13C FLUX & METABOLIC RATE

心脏 13C 通量的磁共振

• 批准号: 2225370
• 负责人: E DOUGLAS LEWANDOWSKI
• 金额: $ 24.46万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 1997-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2225370
• 关键词: Krebs' cycle; alpha ketoglutarate; bioenergetics; chemical kinetics; glutamates; heart metabolism; laboratory rabbit; mitochondria; nuclear magnetic resonance spectroscopy; oxidation; oxygen consumption; radiotracer

Dynamic nuclear magnetic resonance (NMR) spectroscopy of presteady state, carbon-13 (13C) entry into the NMR detectable glutamate pool will be developed and applied to metabolic evaluations of the functional state of whole hearts. Long term objectives are: l) to characterize presteady state changes in I3C NMR spectra of intact hearts as a non-destructive probe of carbon flux through pathways of intermediary metabolism, and 2) to take advantage of the unique information provided by I3C NMR to elucidate the mechanisms of metabolic support of cardiac performance. Achievement of these goals requires: l) date interpretation of presteady state changes in 13C spectra, and 2) identification of metabolic correlates to physiological function. At present, 13C NMR is not sufficiently developed to unambiguously correlate the rate of 13C appearance in the NMR detectable glutamate pool with mitochondrial activity. Preliminary work suggests that 13C labeling and recycling of glutamate may reflect different rate limiting components of the tricarboxylic acid (TCA) cycle under different physiological conditions. Shifts in both metabolic flux and tissue metabolite pools occur in response to changes in physiological function, but these metabolic events are not well characterized in the intact myocardium. Recent findings that dynamic changes in 13C spectra from intact hearts are closely related to mechanical work and respiratory activity indicate that 13C NMR is sensitive to such shifts in the metabolic support of cardiac performance. Thus, we propose to combine I3C NMR of isolated rabbit hearts and in vitro biochemical analysis with separate radiotracer analysis of metabolite oxidation and efflux from isolated mitochondria. This proposal is specifically aimed at identifying how the balance between alpha- ketoglutarate oxidation by the TCA cycle and the efflux of alpha- ketoglutarate for conversion to cytosolic glutamate determines the kinetics of 13C entry into glutamate. With systematically defined, kinetic parameters for glutamate labeling, we will apply 13C NMR to measure metabolic rates at different workloads in intact hearts. A kinetic model will be applied for data analysis and will he further developed as an accurate model of 13C turnover within the TCA cycle. Proposed experiments will generate information, on the response of carbon flux to work load, not currently available with other techniques or protocols. Ultimate applications will include use of 13C NMR spectroscopy to evaluate biochemical activity in hearts without need of tissue biopsy sampling.

Presteady状态的动态核磁共振（NMR）光谱 碳13（13C）进入NMR可检测到的谷氨酸池将是 开发并应用于对功能状态的代谢评估 全心全意。长期目标是：l）表征Presteady 完整心脏I3C NMR光谱的状态变化是无损的 通过中介代谢途径的碳通量探针，2） 利用I3C NMR提供的独特信息 阐明了心脏性能的代谢支持机制。 实现这些目标需要：l）对Presteady的日期解释 13C光谱中的状态变化，2）代谢识别 与生理功能相关。目前，13c NMR不是 足够开发以明确地将13c的速率相关联 用线粒体出现在NMR可检测的谷氨酸池中 活动。初步工作表明13C标签和回收 谷氨酸可能反映了不同速率的限制成分 在不同的生理条件下，三羧酸（TCA）周期。 代谢通量和组织代谢物池的变化发生在 对生理功能变化的反应，但是这些代谢事件 在完整的心肌中没有很好的特征。最近的发现 完整心脏的13C光谱中的动态变化与 机械工作和呼吸活动表明13C NMR为 对心脏性能的代谢支持的这种转变敏感。 因此，我们建议将孤立的兔子心的I3C NMR和 通过单独的放射性示例分析的体外生化分析 来自分离的线粒体的代谢产物氧化和外排。这个建议 专门旨在确定α-之间的平衡 通过TCA循环和α-的外排氧化的酮谷酸酯氧化 酮氯戊酸转化为胞质谷氨酸的确定 13C进入谷氨酸的动力学。有系统定义的 谷氨酸标记的动力学参数，我们将将13C NMR应用于 在完整心脏中的不同工作负载下测量代谢率。一个 动力学模型将用于数据分析，他将进一步 开发为在TCA周期内的13C营业额的准确模型。 建议的实验将生成有关碳响应的信息 用于工作负载的通量，目前尚不适用于其他技术或 协议。最终应用将包括使用13C NMR光谱法 评估心脏中的生化活性而无需组织活检 采样。