Maggs D G, Jacob R, Rife F, Caprio S, Tamborlane W V, Sherwin R S
Section of Endocrinology, Yale University, New Haven, Connecticut 06510, USA.
Diabetes. 1997 Jan;46(1):70-6. doi: 10.2337/diab.46.1.70.
We used microdialysis to distinguish the effects of hyperinsulinemia and hypoglycemia on glucose, gluconeogenic substrate, and catecholamine levels in adipose and muscle extracellular fluid (ECF). Ten lean humans (six males and four females) were studied during baseline and hyperinsulinemic (3 mU x kg-1 x min-1 for 3 h) euglycemia (5.0 mmol/l) and hypoglycemia (2.8 mmol/l). In muscle and adipose, basal ECF glucose was lower (muscle, 3.5 +/- 0.2 mmol/l; adipose tissue, 3.3 +/- 0.2 mmol/l) and lactate was higher (muscle, 2.2 +/- 0.2 mmol/l; adipose, 1.5 +/- 0.3 mmol/l) than respective plasma values (glucose, 4.9 +/- 0.1 mmol/l; lactate, 0.7 +/- 0.1 mmol/l), whereas alanine was higher in muscle ECF (379 +/- 22 micromol/l) than adipose tissue (306 +/- 22 micromol/l) and plasma (273 +/- 33 micromol/l). Plasma catecholamines (unchanged during euglycemia) rose during hypoglycemia with epinephrine, increasing approximately fivefold more than norepinephrine. In contrast, the hypoglycemia-induced increments in muscle dialysate norepinephrine and epinephrine were similar, suggesting local generation of norepinephrine. Compared with euglycemia, hypoglycemia produced a greater increase in lactate and a smaller reduction in alanine in muscle ECF, whereas hypoglycemia caused a greater relative fall in ECF glucose concentrations in muscle (72 +/- 16%) and adipose tissue (69 +/- 9%) than in plasma (42 +/- 3%) (P < 0.05). We conclude that hypoglycemia increases the generation of norepinephrine and gluconeogenic substrates in key target tissues, while increasing the plasma-tissue concentration gradient for glucose. These changes suggest the stimulation of glucose extraction by peripheral tissues, despite systemic counterregulatory hormone release and local sympathetic activation.
我们采用微透析技术来区分高胰岛素血症和低血糖对脂肪及肌肉细胞外液（ECF）中葡萄糖、糖异生底物以及儿茶酚胺水平的影响。对10名体型偏瘦的人（6名男性和4名女性）在基础状态、高胰岛素血症（3 mU·kg⁻¹·min⁻¹，持续3小时）导致的血糖正常（5.0 mmol/L）以及低血糖（2.8 mmol/L）状态下进行了研究。在肌肉和脂肪组织中，基础ECF葡萄糖水平低于（肌肉，3.5±0.2 mmol/L；脂肪组织，3.3±0.2 mmol/L）各自的血浆水平（葡萄糖，4.9±0.1 mmol/L），而乳酸水平高于（肌肉，2.2±0.2 mmol/L；脂肪组织，1.5±0.3 mmol/L）血浆水平（乳酸，0.7±0.1 mmol/L），而肌肉ECF中的丙氨酸水平（379±22 μmol/L）高于脂肪组织（306±22 μmol/L）和血浆（273±33 μmol/L）。血浆儿茶酚胺（在血糖正常期间无变化）在低血糖期间升高，肾上腺素升高幅度比去甲肾上腺素大约高五倍。相反，低血糖诱导的肌肉透析液中去甲肾上腺素和肾上腺素的升高幅度相似，提示去甲肾上腺素的局部生成。与血糖正常相比，低血糖导致肌肉ECF中乳酸增加幅度更大，丙氨酸减少幅度更小，而低血糖导致肌肉（72±16%）和脂肪组织（69±9%）中ECF葡萄糖浓度相对于血浆（42±3%）下降幅度更大（P<0.05）。我们得出结论，低血糖会增加关键靶组织中去甲肾上腺素和糖异生底物的生成，同时增加葡萄糖的血浆 - 组织浓度梯度。这些变化表明，尽管存在全身反调节激素释放和局部交感神经激活，但外周组织对葡萄糖的摄取仍受到刺激。
