- The Effect of alpha-lipoic Acid on Endothelial Dysfunction Induced by Intralipid Infusion in Healthy Volunteers.
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Dong Wook Lee, Mi Jung Kim, Hye Soon Kim, Tae Sung Yun, Ho Chan Cho, Sang Jun Lee, Seung Ho Hur, Kyo Cheol Mun, Yong Won Cho, Jae Hoon Bae, In Kyu Lee
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Korean Diabetes J. 2002;26(5):336-346. Published online October 1, 2002
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 Abstract
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- BACKGROUND
Endothelial dysfunciton has been proposed as an early manifestation of atherogenesis. Recently, emerging evidence suggests that hypertriglyceridemia and elevated free fatty acid are important risk factors in the development of atherosclerosis, probably through an increased oxidative stress. To clarify the hypothesis, we evaluated the effect of alpha-lipoic acid (ALA) on the endothelial dysfunction induced by intralipid infusion in healthy volunteers. METHODS: Hypertriglyceridemia and elevated free fatty acids was induced by infusion of intralipid. FMD (Flow-mediated dilation) of the brachial artery was investigated noninvasively by a high-resolution ultrasound technique in 13 young, healthy men without risk factors for coronary heart disease. RESULTS: Plasma triglyceride, free fatty acid and the superoxide anion were increased from 61.7+/-28.8 to 332.6+/-202.5 mg/dL, from 330.7+/-131.1 to 1267.0+/-486.2 microEq/L and from 6.6+/-2.2 to 8.7+/-1.5 X 10(-7)nmol/10(6)cells/30min (vs. basal p<0.001), respectively, following infusion of the intralipid. The FMD was decreased from 10.1+/-3.3 to 7.7+/-3.7% (vs. basal p<0.01) following infusion of the intralipid. After treatment with ALA, the increase in the FMD and the decrease in superoxide anion were significant. CONCLUSION: Acute hypertriglyceridemia, induced by intralipid infusion, is implicated in endothelial dysfunction. This endothelial dysfunction was reversed by treatment with ALA. These results suggest that chronic and repeated hypertriglyceridemia may play important roles in the development of atherosclerosis probably by increasing oxidative stress.
- The Effect of alpha-Lipoic Acid on Vascular Smooth Muscle Cell Proliferation, Migration, Neointimal Formation and PAI-1 Expression.
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Dong Woo Shin, Dong Wook Lee, Sang Jun Lee, Hye Soon Kim, Hyo Gyoung Kang, Jong Deok Ahn, In Kyu Lee
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Korean Diabetes J. 2001;25(6):446-459. Published online December 1, 2001
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Abstract
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- BACKGROUND
Exposure to large amounts of glucose causes a characteristic dysfunction and morphologic changes of the endothelium by an increased production of reactive oxygen species (ROS) in diabetes. The plasminogen activator inhibitor-1 (PAI-1), which modulates fibrinolysis and cell migration, may influence proteolysis and neointimal formation in vascular smooth muscle cells (VSMC). Antioxidants have been proposed to inhibit multiple proatherogenic events. This study investigated the effect of (alpha)-Lipoic acid on PAI-1 expression and VSMC proliferation and migration both in vivo and in vitro. METHODS: In the in vitro study, cultured rat aortic smooth muscle cells (RASMC) were incubated in a medium containing high glucose (22 mM) and 100 nM angiotensin II for 4 hour. After (alpha)-Lipoic acidtreatment, a -migration and growth assay of the RASMC, and a gel mobility shift assay and reporter gene analysis for nuclear factor- B (NF-kappa B) and northern blot analysis for PAI-1 were performed. In the in vivo study, the effect of (alpha)-Lipoic acid on neointimal hyperplasia in a rat carotid balloon injury model was evaluated. RESULTS: RASMC migration was inhibited significantly by (alpha)-Lipoic acid (p<0.01), but their proliferation was not inhibited. The NF-kappa B DNA binding activity and NF-kappa B promoter activity was inhibited by (alpha)-Lipoic acid significantly (p<0.01). (alpha)-Lipoic acid inhibited PAI-1 mRNA expression by high glucose and angiotensin II in dose dependent manner (p<0.05). In the rat carotid artery balloon injury model, neointimal formation was reduced by (alpha)-Lipoic acid treatment in a dose dependent manner significantly (p<0.01). CONCLUSION: (alpha)-Lipoic acid suppresses migration, but not proliferation in RASMC. (alpha)-Lipoic acid also reduce neointima formation in a rat carotid balloon injured model. This effect might be related to the blocking of NF-kappa B which increase the expression of the genes associated with atherosclerosis including TNF-alpha, IL-1, IL-6, endothelin-1, MCP-1, VCAM-1, ICAM-1, E-selectin, tissue factor.
- The Effect of Acute Hyperglycemia on Endothelial Function in Type 2 Diabetes.
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Sang Jun Lee, Dong Wook Lee, In Kyu Lee
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Korean Diabetes J. 2000;24(5):574-586. Published online January 1, 2001
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Abstract
- BACKGROUND
Multiple studies in patients with diabetes demonstrate impaired endothelial-dependent vasodilation. But the mechanisms of vascular dysfunction in type 2 diabetes are still controversial. Some risk factors, such as dyslipidemia, hypertension and obesity, are commonly associated with type 2 diabetes. These risk factor may cause endothelial dysfunction. And hyperglycemia may have a specific role in the increased risk of vascular complications in diabetes but it remains unclear. The purpose of this study was to examine whether endothelial dysfunction occurs when acute hyperglycemia is induced by oral glucose loading. METHOD: Using the high-resolution ultrasound, we measured flow-mediated vasodilation (endothelial dependent vasodilation: FMD) during oral glucose tolerance test in 11 men (mean age: 59+/-5 years) with type 2 diabetes without chronic diabetic complications. For statistical analysis, we used paired t-test, generalized linear method (GLM) to compare FMD before and after glucose loading. RESULT: Flow-mediated vasodilation was diminished after glucose loading (13.2+/- 6.4%, 7.3+/-3.3*%, 12.8+/-5.6%, in fasting, at 1- and 2-h, respectively; *p<0.001 vs fasting). Superoxide anion formation by neutrophils was increased after glucose loading (4.65+/-2.8, 6.17+/-2.2, in fasting, at 1-h respectively: p<0.05 vs fasting)( 10-7nmol/106cells/30min). Endothelial independent vasodilation was not significantly affected by glucose loading. The concentration of triglyceride were not changed after glucose loading. CONCLUSION: This study shows that acute hyperglycemia induced by 75 gm oral glucose intake results in endothelial dysfunction. These results suggest that prolonged and repeated hyperglycemia may play an important role in the developement and progression of vascular complication in diabetes.
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