Department of Internal Medicine, University Hospital Maastricht, P. Debyelaan 25, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands.
Diabetologia. 2010 May;53(5):989-1000. doi: 10.1007/s00125-010-1677-0. Epub 2010 Feb 26.
AIMS/HYPOTHESIS: Impaired nitric oxide (NO)-dependent vasorelaxation plays a key role in the development of diabetic vascular complications. We investigated the effect of hyperglycaemia on impaired vasoreactivity and a putative role therein of the AGE precursor methylglyoxal.
The effects of high glucose and methylglyoxal on NO-dependent vasorelaxation in isolated rat mesenteric arteries from wild-type and transgenic glyoxalase (GLO)-I (also known as GLO1) rats, i.e. the enzyme detoxifying methylglyoxal, were recorded in a wire myograph. AGE formation of the major methylglyoxal-adduct 5-hydro-5-methylimidazolone (MG-H1) was detected with an antibody against MG-H1 and quantified with ultra-performance liquid chromatography (tandem) mass spectrometry. Reactive oxygen species formation was measured with a 5-(and-6)-chloromethyl-2'7'-dichlorodihydrofluorescein diacetate acetyl ester probe and by immunohistochemistry with an antibody against nitrotyrosine.
High glucose and methylglyoxal exposure of mesenteric arteries significantly reduced the efficacy of NO-dependent vasorelaxation (p < 0.05). This impairment was not observed in mesenteric arteries of GLO-I transgenic rats indicating a specific intracellular methylglyoxal effect. The diabetes-induced impaired potency (pD(2)) in mesenteric arteries of wild-type rats was significantly improved by GLO-I overexpression (p < 0.05). Methylglyoxal-modified albumin did not affect NO-dependent vasorelaxation, while under the same conditions the receptor for AGE ligand S100b did (p < 0.05). Methylglyoxal treatment of arteries increased intracellular staining of MG-H1 in endothelial cells and adventitia by fivefold accompanied by an eightfold increase in the oxidative stress marker nitrotyrosine. Antioxidant pre-incubation prevented methylglyoxal-induced impairment of vasoreactivity.
CONCLUSIONS/INTERPRETATION: These data show that hyperglycaemia-induced impairment of endothelium-dependent vasorelaxation is mediated by increased intracellular methylglyoxal levels in a pathway dependent on oxidative stress.
目的/假设：一氧化氮（NO）依赖性血管舒张受损在糖尿病血管并发症的发展中起着关键作用。我们研究了高血糖对血管反应性的影响，以及其中可能存在的AGE 前体甲基乙二醛的作用。
在离体大鼠肠系膜动脉中，使用 wire myograph 记录高葡萄糖和甲基乙二醛对野生型和转 Glyoxalase (GLO)-I（也称为 GLO1）大鼠（即，清除甲基乙二醛的酶）NO 依赖性血管舒张的影响。使用针对 MG-H1 的抗体检测主要的甲基乙二醛加合物 5-羟-5-甲基咪唑烷酮（MG-H1）的形成，并使用超高效液相色谱（串联）质谱进行定量。通过 5-（和 6）-氯甲基-2'7'-二氯二氢荧光素二乙酸酯乙酰酯探针和针对硝基酪氨酸的免疫组织化学测量活性氧形成。
高葡萄糖和甲基乙二醛暴露显著降低了肠系膜动脉中 NO 依赖性血管舒张的效力（p < 0.05）。在 GLO-I 转基因大鼠的肠系膜动脉中未观察到这种损伤，表明存在特定的细胞内甲基乙二醛作用。野生型大鼠肠系膜动脉中糖尿病诱导的效力降低（pD（2））通过 GLO-I 过表达得到显著改善（p < 0.05）。甲基乙二醛修饰的白蛋白不会影响 NO 依赖性血管舒张，而在相同条件下，AGE 配体 S100b 的受体则会（p < 0.05）。甲基乙二醛处理动脉增加了内皮细胞和外膜中 MG-H1 的细胞内染色，氧化应激标志物硝基酪氨酸增加了八倍。抗氧化剂预处理可防止甲基乙二醛诱导的血管反应性损伤。
结论/解释：这些数据表明，高血糖诱导的内皮依赖性血管舒张受损是由依赖于氧化应激的途径中细胞内甲基乙二醛水平升高介导的。
