Brooks George A
Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States.
Front Nutr. 2021 Apr 22;8:663560. doi: 10.3389/fnut.2021.663560. eCollection 2021.
After almost a century of misunderstanding, it is time to appreciate that lactate shuttling is an important feature of energy flux and metabolic regulation that involves a complex series of metabolic, neuroendocrine, cardiovascular, and cardiac events . Cell-cell and intracellular lactate shuttles in the heart and between the heart and other tissues fulfill essential purposes of energy substrate production and distribution as well as cell signaling under fully aerobic conditions. Recognition of lactate shuttling came first in studies of physical exercise where the roles of driver (producer) and recipient (consumer) cells and tissues were obvious. One powerful example of cell-cell lactate shuttling was the exchange of carbohydrate energy in the form of lactate between working limb skeletal muscle and the heart. The exchange of mass represented a conservation of mass that required the integration of neuroendocrine, autoregulatory, and cardiovascular systems. Now, with greater scrutiny and recognition of the effect of the cardiac cycle on myocardial blood flow, there brings an appreciation that metabolic fluxes must accommodate to pressure-flow realities within an organ in which they occur. Therefore, the presence of an intra-cardiac lactate shuttle is posited to explain how cardiac mechanics and metabolism are synchronized. Specifically, interruption of blood flow during the isotonic phase of systole is supported by glycolysis and subsequent return of blood flow during diastole allows for recovery sustained by oxidative metabolism.
经过近一个世纪的误解，现在是时候认识到乳酸穿梭是能量通量和代谢调节的一个重要特征，它涉及一系列复杂的代谢、神经内分泌、心血管和心脏事件。心脏内以及心脏与其他组织之间的细胞间和细胞内乳酸穿梭在完全有氧条件下实现了能量底物产生和分配以及细胞信号传导的重要目的。乳酸穿梭最早是在体育锻炼研究中被认识到的，在这些研究中，驱动（产生）细胞和组织与接受（消耗）细胞和组织的作用很明显。细胞间乳酸穿梭的一个有力例子是工作肢体骨骼肌和心脏之间以乳酸形式进行的碳水化合物能量交换。质量交换代表了质量守恒，这需要神经内分泌、自动调节和心血管系统的整合。现在，随着对心动周期对心肌血流影响的更深入研究和认识，人们认识到代谢通量必须适应其发生器官内的压力 - 血流实际情况。因此，心脏内乳酸穿梭的存在被认为可以解释心脏力学和代谢是如何同步的。具体而言，收缩期等张阶段的血流中断由糖酵解支持，而舒张期随后的血流恢复则允许通过氧化代谢实现恢复。
