Hagström E, Arner P, Ungerstedt U, Bolinder J
Department of Medicine, Huddinge Hospital, Karolinska Institute, Stockholm, Sweden.
Am J Physiol. 1990 May;258(5 Pt 1):E888-93. doi: 10.1152/ajpendo.1990.258.5.E888.
The in vivo kinetics of lactate and pyruvate in the extracellular space of subcutaneous adipose tissue after glucose ingestion were investigated in healthy volunteers by the use of a microdialysis sampling technique. Comparison was made with the metabolite levels in venous plasma. The absolute subcutaneous tissue concentrations of lactate and pyruvate were estimated in the fasting state by perfusion with varying lactate- and pyruvate-containing solutions. An equilibrium with the surrounding extracellular fluid was found for both lactate and pyruvate in concentrations similar to those in venous plasma. After glucose ingestion there was an increase in the circulating levels of glucose, lactate, and pyruvate, which returned to base-line values within 3 h. There was a more marked increase in lactate in subcutaneous adipose tissue than in venous blood, and the adipose tissue lactate remained elevated for at least 3 h. In contrast, pyruvate levels increased much less in subcutaneous fat than in venous blood. The addition of isoproterenol (which inhibits adipose tissue glucose metabolism) to the tissue perfusate lowered the subcutaneous tissue lactate levels significantly but did not affect the subcutaneous pyruvate levels. These data suggest that human subcutaneous adipose tissue is a source of in vivo lactate production after glucose ingestion. Since lactate is thought to be a major substrate for glycogen synthesis in the liver, the present findings may provide evidence of a new and important role of the adipose tissue metabolism in the regulation of whole body glucose homeostasis in humans.
通过使用微透析采样技术，在健康志愿者中研究了葡萄糖摄入后皮下脂肪组织细胞外空间中乳酸和丙酮酸的体内动力学。并与静脉血浆中的代谢物水平进行了比较。通过用不同含乳酸和丙酮酸的溶液进行灌注，在禁食状态下估计了乳酸和丙酮酸在皮下组织中的绝对浓度。发现乳酸和丙酮酸与周围细胞外液达到平衡，其浓度与静脉血浆中的浓度相似。葡萄糖摄入后，循环中的葡萄糖、乳酸和丙酮酸水平升高，并在3小时内恢复到基线值。皮下脂肪组织中乳酸的增加比静脉血中更明显，且脂肪组织中的乳酸至少升高3小时。相比之下，皮下脂肪中丙酮酸水平的升高远低于静脉血。在组织灌流液中添加异丙肾上腺素（抑制脂肪组织葡萄糖代谢）可显著降低皮下组织乳酸水平，但不影响皮下丙酮酸水平。这些数据表明，人体皮下脂肪组织是葡萄糖摄入后体内乳酸产生的来源。由于乳酸被认为是肝脏中糖原合成的主要底物，目前的研究结果可能为脂肪组织代谢在调节人体全身葡萄糖稳态中的新的重要作用提供证据。
