Multinuclear NMR Spectroscopy of Myocardial Energetics and Substrate Utilization in Isolated Perfused Mouse Hearts

摘要: In experimental cardiovascular physiology, non­ invasive and repeated measures of cardiac function, energetics, metabolism provide a dynamic picture myocardial performance during phys­ iological or pathological perturbations. All these parameters can be assessed in one sample by combining isolated perfused heart experiments with multinuclear nuclear magnetic resonance (NMR) spectroscopic approach. This method is advantageous because simultaneous measurements left ventricular (LV) substrate utilization are made contracting heart. NMR spectroscopy allows the user to measure metabolite content, as well turnover rate, assessing content specific nucleus biological samples [1,2]. For example, P used quantify phosphorous­ containing compounds sample. The most abundant phosphates cell high­energy phosphocreatine ATP. Thus, assess energetics various studies bioengineered mouse models under conditions [3–6]. With this method, changes ATP repetitive physiological and/or pertur­ bations providing detailed energetic status. Assessment presents unique challenge that, although carbon­ relatively heart, natural abundance visible carbon isotope (C) very low (∼1–3%). Therefore, isotopic enrichment substrates delivered required. C­labeled chosen based on C­labeling pattern acetyl CoAs that ultimately yielded. Since glutamate easily detected C similar TCA cycle intermediate, α­ketoglutarate steady­state conditions, inferences isotopic­enriched entry into tricarboxcylic acid (TCA) examining labeling glutamate. As shown Figure 41.1A, glucose carbons 1st 6th position (1,6­C glucose) will yield two CoA molecules 2nd (2­C CoA) once glycolysis pyruvate decarboxylation completed. Entry