Study Of Vascular Endothelium Dysfunction In Patients With Metabolic Syndrome And Its Mechanism

Objective: The aim of this study was designed to investigate the impaired status of vascular endothelial function of patients with metabolic syndrome (MS) and the association between endothelium dysfunction and risk factors for cardiovascular disease and asymmetric dimethylarginine(ADMA) and to explore the possible mechanisms of endothelium dysfunction by detecting the flow-mediated dilation (FMD) in the brachial artery of the patients with MS, and comparing with the FMD of patients with essential hypertension(EH) and normal controls.Methods: Seventy-two subjects were divided into three groups: normal control(NC) group (n=20), EH group (n=26) and MS group (n=26). The blood lipid, fasting blood glucose (FBG) and blood serum levels of ADMA were measured and FMD and nitroglycerin-induced dilation (NID) in the brachial artery were assessed by high-resolution ultrasound technique.Results:1. The systolic blood pressure (SBP), diastolic blood pressure (DBP) and pulse pressure (PP) were higher and the levels of high-density lipoprotein cholesterol (HDL-C) were lower in EH group than that in NG group (all P<0.01), while there was no significant difference in other parameters (all P >0.05). The SBP, DBP, PP, body mass index (BMI), waistline, triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), FBG in MS group were higher than that in NC group CP <0.05 or 0.01) , and the levels of HDL-C were lower (P<0.01). As compared with EH group, the SBP, DBP, PP in MS group were lower, but the BMI, TG, LDL-C, FBG were higher (P<0.05 or 0.01) and the levels of HDL-C were lower (P <0.01) in MS group.2. The levels of ADMA in MS group and EH group were significantly increased than that in NC group (0.81±0.15umol/L, 0.69±0.14umol/L and 0.45±0.09umol/L, respectively, all P<0.01). The level of ADMA was the highest in MS group and there was a significant difference between MS group and EH group (P<0.01).3. The FMD and the NID in MS group (7.61%±2.56% and 14.10%±2.94%) and EH group (9.61%±2.57% and 14.63%±2.94%) were significantly decreased than that in NC group (11.85%±2.13% and 16.57%±2.77%) (P<0.01 or <0.05). There was a significant difference of the FMD between MS group and EH group (P<0.01), whereas the difference of the NID between MS group and EH group was no significant (P>0.05).4. The Pearson correlation analysis revealed that the HDL-C and the NID positively correlated with the FMD (P<0.01), while the SBP, DBP, PP, TG, LDL-C, FBG, ADMA, baseline diameter (BD) of brachial artery negatively correlated with FMD (P<0.05 or <0.01).5. Multiple linear regress analysis showed that the independent factors of influence on FMD were the FBG (Beta =-0.412, P= 0.005) and the SBP (Beta= -0.332, P= 0.022).Conclusions:1. The metabolic syndrome is characterized by a group of metabolic risk factors in one person.2. Both metabolic syndrome and essential hypertension may induce endothelial dysfunction which is more serious in the patients with metabolic syndrome.3. Hypertension, abnormal lipid metabolism, hyperglycemia and elevated ADMA levels can all impair endothelial function, while the SBP and FBG have the greatest impact on the endothelial function.4. The effective control of the blood pressure and blood sugar and the comprehensive treatment including blood lipid adjustment and weight control in the treatment of the patients with metabolic syndrome are beneficial to the improvement of their endothelial function and the prevention of cardiovascular and cerebrovascular complications.