Brooks George A
Department of Integrative Biology, University of California, Berkeley, CA, USA.
Docteur Honoris Causa, de l'Université Montpellier, Montpellier, France.
Adv Exp Med Biol. 2025;1478:3-18. doi: 10.1007/978-3-031-88361-3_1.
From contemporary studies of muscle and other tissues and whole-body metabolism, we now know that lactate is continuously produced under fully aerobic conditions in a variety of cells, tissues, and organs and serves at least three purposes-lactate is a preferred energy substrate, the major gluconeogenic precursor, and a signaling molecule. In sequence, from studies of exercise physiology, several lactate shuttles were discovered. These were the cell-cell and intracellular lactate shuttles with the astrocyte-neuron shuttles subsets of the former, and peroxisomal and cytosolic-mitochondrial lactate shuttles subsets of the latter. Most recently, with discovery of the postprandial lactate shuttle (PLS), we now realize that muscle, heart, brain, and liver lactate shuttle events are at either intermediate or terminal ends of carbohydrate carbon flow that commences when dietary carbohydrate enters the duodenum and is converted to lactate. There are two major phases of the PLS: enteric PLS (involving gut lactate production and lactate appearance in the systemic circulation) and the systemic PLS (involving hepatic glucose release, tissue glucose uptake and lactate production, and tissue lactate release). Hence, in terms of our understanding of body carbohydrate carbon flux, the gut is first and muscles are last (Matthew 20:16).
通过对肌肉及其他组织和全身代谢的当代研究，我们现在知道，在完全有氧的条件下，多种细胞、组织和器官会持续产生乳酸，且乳酸至少有三个作用——它是一种优质的能量底物、主要的糖异生前体和一种信号分子。接着，从运动生理学研究中，人们发现了几种乳酸穿梭机制。其中包括细胞间和细胞内乳酸穿梭机制，前者有星形胶质细胞 - 神经元穿梭机制的亚型，后者有过氧化物酶体和胞质 - 线粒体乳酸穿梭机制的亚型。最近，随着餐后乳酸穿梭机制（PLS）的发现，我们现在意识到，肌肉、心脏、大脑和肝脏中的乳酸穿梭事件处于碳水化合物碳流的中间或末端，碳水化合物碳流始于膳食碳水化合物进入十二指肠并转化为乳酸之时。PLS有两个主要阶段：肠道PLS（涉及肠道乳酸生成和乳酸进入体循环）和全身PLS（涉及肝脏葡萄糖释放、组织葡萄糖摄取和乳酸生成，以及组织乳酸释放）。因此，就我们对身体碳水化合物碳流的理解而言，肠道是第一步，而肌肉是最后一步（《马太福音》20:16）。
