Amsterdam UMC, Laboratory of Experimental Intensive Care and Anesthesiology, Department of Anesthesiology, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
Amsterdam Cardiovascular Sciences Institute, Amsterdam, The Netherlands.
Basic Res Cardiol. 2024 Jun;119(3):403-418. doi: 10.1007/s00395-024-01042-4. Epub 2024 Mar 25.
Decreased nicotinamide adenine dinucleotide (NAD) levels contribute to various pathologies such as ageing, diabetes, heart failure and ischemia-reperfusion injury (IRI). Nicotinamide riboside (NR) has emerged as a promising therapeutic NAD precursor due to efficient NAD elevation and was recently shown to be the only agent able to reduce cardiac IRI in models employing clinically relevant anesthesia. However, through which metabolic pathway(s) NR mediates IRI protection remains unknown. Furthermore, the influence of insulin, a known modulator of cardioprotective efficacy, on the protective effects of NR has not been investigated. Here, we used the isolated mouse heart allowing cardiac metabolic control to investigate: (1) whether NR can protect the isolated heart against IRI, (2) the metabolic pathways underlying NR-mediated protection, and (3) whether insulin abrogates NR protection. NR protection against cardiac IRI and effects on metabolic pathways employing metabolomics for determination of changes in metabolic intermediates, and C-glucose fluxomics for determination of metabolic pathway activities (glycolysis, pentose phosphate pathway (PPP) and mitochondrial/tricarboxylic acid cycle (TCA cycle) activities), were examined in isolated C57BL/6N mouse hearts perfused with either (a) glucose + fatty acids (FA) ("mild glycolysis group"), (b) lactate + pyruvate + FA ("no glycolysis group"), or (c) glucose + FA + insulin ("high glycolysis group"). NR increased cardiac NAD in all three metabolic groups. In glucose + FA perfused hearts, NR reduced IR injury, increased glycolytic intermediate phosphoenolpyruvate (PEP), TCA intermediate succinate and PPP intermediates ribose-5P (R5P) / sedoheptulose-7P (S7P), and was associated with activated glycolysis, without changes in TCA cycle or PPP activities. In the "no glycolysis" hearts, NR protection was lost, whereas NR still increased S7P. In the insulin hearts, glycolysis was largely accelerated, and NR protection abrogated. NR still increased PPP intermediates, with now high C-labeling of S7P, but NR was unable to increase metabolic pathway activities, including glycolysis. Protection by NR against IRI is only present in hearts with low glycolysis, and is associated with activation of glycolysis. When activation of glycolysis was prevented, through either examining "no glycolysis" hearts or "high glycolysis" hearts, NR protection was abolished. The data suggest that NR's acute cardioprotective effects are mediated through glycolysis activation and are lost in the presence of insulin because of already elevated glycolysis.
烟酰胺腺嘌呤二核苷酸 (NAD) 水平降低会导致各种病理状态，如衰老、糖尿病、心力衰竭和缺血再灌注损伤 (IRI)。烟酰胺核糖 (NR) 作为一种有前途的治疗 NAD 前体，由于能够有效提高 NAD 水平，最近被证明是唯一能够降低临床相关麻醉模型中心脏 IRI 的药物。然而，NR 通过何种代谢途径介导 IRI 保护仍不清楚。此外，胰岛素作为一种已知的心脏保护作用调节剂，对 NR 保护作用的影响尚未被研究。在这里，我们使用分离的小鼠心脏来研究：（1）NR 是否可以保护分离的心脏免受 IRI，（2）NR 介导保护作用的代谢途径，以及（3）胰岛素是否会破坏 NR 的保护作用。我们采用代谢组学来确定代谢中间产物的变化，以及 C-葡萄糖通量组学来确定代谢途径的活性（糖酵解、磷酸戊糖途径 (PPP) 和线粒体/三羧酸循环 (TCA 循环)），检测 NR 对分离的 C57BL/6N 小鼠心脏IRI 的保护作用及其对代谢途径的影响，这些心脏在以下三种代谢组中进行灌注：（a）葡萄糖+脂肪酸（“轻度糖酵解组”），（b）乳酸+丙酮酸+FA（“无糖酵解组”），或（c）葡萄糖+FA+胰岛素（“高糖酵解组”）。NR 在所有三种代谢组中均增加了心脏 NAD。在葡萄糖+FA 灌注的心脏中，NR 减少了 IRI 损伤，增加了糖酵解中间产物磷酸烯醇丙酮酸 (PEP)、TCA 中间产物琥珀酸和 PPP 中间产物核糖-5P (R5P)/景天庚酮糖-7P (S7P)，并与糖酵解的激活有关，而 TCA 循环或 PPP 活性没有变化。在“无糖酵解”心脏中，NR 的保护作用丧失，而 NR 仍能增加 S7P。在胰岛素心脏中，糖酵解大大加速，NR 保护作用被阻断。NR 仍能增加 PPP 中间产物，S7P 的 C 标记物含量现在很高，但 NR 不能增加代谢途径的活性，包括糖酵解。NR 对 IRI 的保护作用仅存在于糖酵解水平较低的心脏中，并与糖酵解的激活有关。当通过检查“无糖酵解”心脏或“高糖酵解”心脏来防止糖酵解的激活时，NR 的保护作用被消除。数据表明，NR 的急性心脏保护作用是通过糖酵解的激活介导的，并且在胰岛素存在下由于已经升高的糖酵解而丧失。
