Holmäng A, Müller M, Andersson O K, Lönnroth P
Wallenberg Laboratory, Department of Heart and Lung Diseases, Göteborg University, Sweden.
Am J Physiol. 1998 Mar;274(3):E446-52. doi: 10.1152/ajpendo.1998.274.3.E446.
To study the regulation of the interstitial glucose concentration in skeletal muscle, nine control subjects and nine older and overweight non-insulin-dependent diabetes mellitus (NIDDM) subjects with extreme insulin resistance were investigated with microdialysis in the medial femoral muscle before and during a euglycemic insulin clamp. After an overnight fast, arterial plasma glucose concentration was 4.9 +/- 0.1 and 8.5 +/- 0.6 mmol/l (P < 0.001), respectively. The arterial-interstitial concentration ([a-i]) differences of glucose and lactate were 0.43 +/- 0.16 (P < 0.05) and -0.13 +/- 0.05 mmol/l, respectively, in normal subjects. In NIDDM subjects, [a-i] differences for glucose and lactate were nonsignificant. Muscle blood flow was similar in controls and NIDDM subjects. During the glucose clamp, the glucose [a-i] differences increased and the lactate [a-i] differences decreased significantly in both groups. The glucose 170 infusion rate was 8.0 +/- 0.77 vs. 3.2 +/- 0.51 mg.kg-1.min-1 (P < 0.001), and blood flow was 9.9 +/- 1.6 vs. 6.7 +/- 0.9 ml.100 g-1.min-1 (P < 0.05) in controls and NIDDM subjects, respectively. These results show that 1) the capillary wall is rate limiting for muscle glucose uptake and lactate release in control subjects but not in postabsorptive hyperglycemic insulin-resistant subjects, 2) vasodilation during insulin infusion does not prevent the increase in [a-i] difference of glucose in normal subjects, and 3) in severely insulin-resistant muscle, the [a-i] difference of glucose is not extended despite lack of vasodilation.
为研究骨骼肌间质葡萄糖浓度的调节机制，对9名对照受试者以及9名年龄较大且超重、患有极端胰岛素抵抗的非胰岛素依赖型糖尿病（NIDDM）受试者，在正常血糖胰岛素钳夹试验前后，采用微透析技术在内侧股肌进行了研究。经过一夜禁食后，动脉血浆葡萄糖浓度分别为4.9±0.1和8.5±0.6 mmol/L（P<0.001）。正常受试者中，葡萄糖和乳酸的动脉-间质浓度（[a-i]）差值分别为0.43±0.16（P<0.05）和-0.13±0.05 mmol/L。在NIDDM受试者中，葡萄糖和乳酸的[a-i]差值无统计学意义。对照组和NIDDM受试者的肌肉血流量相似。在葡萄糖钳夹试验期间，两组的葡萄糖[a-i]差值均增加，而乳酸[a-i]差值均显著降低。对照组和NIDDM受试者的葡萄糖输注速率分别为8.0±0.77与3.2±0.51 mg·kg⁻¹·min⁻¹（P<0.001），血流量分别为9.9±1.6与6.7±0.9 ml·100 g⁻¹·min⁻¹（P<0.05）。这些结果表明：1）在对照受试者中，毛细血管壁对肌肉摄取葡萄糖和释放乳酸起限速作用，而在吸收后高血糖胰岛素抵抗受试者中则不然；2）胰岛素输注期间的血管舒张并不能阻止正常受试者中葡萄糖[a-i]差值的增加；3）在严重胰岛素抵抗的肌肉中，尽管缺乏血管舒张，但葡萄糖的[a-i]差值并未扩大。
