Timimi F K, Ting H H, Haley E A, Roddy M A, Ganz P, Creager M A
Cardiovascular Division, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA.
J Am Coll Cardiol. 1998 Mar 1;31(3):552-7. doi: 10.1016/s0735-1097(97)00536-6.
We sought to determine whether the antioxidant vitamin C improves endothelium-dependent vasodilation of forearm resistance vessels in patients with insulin-dependent diabetes mellitus.
Endothelium-dependent vasodilation is impaired in patients with diabetes mellitus. Oxidatively mediated degradation of endothelium-derived nitric oxide contributes to abnormal endothelium-dependent vasodilation in animal models of diabetes mellitus.
The study group included 10 patients with insulin-dependent diabetes mellitus and 10 age-matched control subjects. Forearm blood flow was determined by venous occlusion plethysmography. Endothelium-dependent vasodilation was assessed by intraarterial infusion of methacholine (0.3 to 10 microg/min). Endothelium-independent vasodilation was assessed by intraarterial infusion of nitroprusside (0.3 to 10 microg/min). Forearm blood flow dose-response curves were determined for each drug infusion before and during concomitant infusion of vitamin C (24 mg/min).
In diabetic subjects, endothelium-dependent vasodilation was augmented by the concomitant infusion of vitamin C (p = 0.001). Endothelium-independent vasodilation was not affected by the concomitant infusion of vitamin C (p = NS). In control subjects, vitamin C infusion did not affect endothelium-dependent vasodilation (p = NS).
Vitamin C selectively restores the impaired endothelium-dependent vasodilation in the forearm resistance vessels of patients with insulin-dependent diabetes mellitus. These findings indicate that nitric oxide degradation by oxygen-derived free radicals contributes to abnormal vascular reactivity in humans with insulin-dependent diabetes mellitus.
我们试图确定抗氧化剂维生素C是否能改善胰岛素依赖型糖尿病患者前臂阻力血管的内皮依赖性血管舒张功能。
糖尿病患者存在内皮依赖性血管舒张功能受损。在糖尿病动物模型中，氧化介导的内皮源性一氧化氮降解导致内皮依赖性血管舒张异常。
研究组包括10例胰岛素依赖型糖尿病患者和10例年龄匹配的对照者。通过静脉阻塞体积描记法测定前臂血流量。通过动脉内输注乙酰甲胆碱（0.3至10微克/分钟）评估内皮依赖性血管舒张功能。通过动脉内输注硝普钠（0.3至10微克/分钟）评估非内皮依赖性血管舒张功能。在同时输注维生素C（24毫克/分钟）之前和期间，分别测定每种药物输注时的前臂血流量剂量反应曲线。
在糖尿病受试者中，同时输注维生素C可增强内皮依赖性血管舒张功能（p = 0.001）。同时输注维生素C对非内皮依赖性血管舒张功能无影响（p =无显著性差异）。在对照者中，输注维生素C对内皮依赖性血管舒张功能无影响（p =无显著性差异）。
维生素C可选择性恢复胰岛素依赖型糖尿病患者前臂阻力血管受损的内皮依赖性血管舒张功能。这些发现表明，氧衍生自由基导致的一氧化氮降解促成了胰岛素依赖型糖尿病患者血管反应性异常。
