PURPOSE: Metabolic syndrome is an important risk factor for cardiovascular disease. Adipokines interfere with insulin action and endothelial cell function. We investigated the relationship among adipokines, metabolic factors, inflammatory markers, and vascular reactivity in obese subjects with metabolic syndrome and lean controls. METHODS: Cross-sectional study of 19 obese subjects with metabolic syndrome and 8 lean volunteers evaluated as controls. Vascular reactivity was assessed by venous occlusion pletysmography measuring braquial forearm blood flow (FBF) and vascular resistance (VR) responses to intra-arterial infusions of endothelium-dependent (acetylcholine-Ach) and independent (sodium nitroprusside-SNP) vasodilators. Blood samples were obtained to evaluate C reactive protein (CRP), plasminogen activator inhibitor 1 (PAI-1), fibrinogen, adiponectin, resistin, and lipid profile. Patients were classified with regard to insulin resistance through the HOMA-IR index. RESULTS: PAI-1, CRP and fibrinogen were higher and adiponectin was lower in metabolic syndrome subjects compared to controls. Metabolic syndrome subjects had impaired vascular reactivity. Adiponectin and PAI-1 were associated with insulin, HOMA-IR, triglycerides, and HDLc; and resistin with CRP. Adiponectin was associated with VR after Ach in the pooled group and resistin with D FBF after Ach in the metabolic syndrome group. CONCLUSION: Metabolic syndrome subjects exhibited low levels of adiponectin and high levels of CRP, fibrinogen, and PAI-1. Adiponectin and PAI-1 correlated with insulin resistance markers. Adiponectin and resistin correlated with vascular reactivity parameters. An adipocyte-endothelium interaction might be an important mechanism of inflammation and vascular dysfunction.

Microvascular dysfunction is an early finding in obesity possibly related to co-morbidities like diabetes and hypertension. Therefore we have investigated changes on microvascular function, body composition, glucose and insulin tolerance tests (GTT and ITT) on male hamsters fed either with high fat (HFD, n=20) or standard (Control, n=21) diet during 16 weeks. Total body fat and protein content were determined by carcass analysis, aorta eNOS and iNOS expression by immunoblotting assay and mean blood pressure (MAP) and heart rate (HR) by an arterial catheter. Microvascular reactivity in response to acetylcholine and sodium nitroprusside, functional capillary density (FCD), capillary recruitment induced by a hyperinsulinemic status and macromolecular permeability after 30 min ischemia was assessed on either cheek pouch or cremaster muscle preparations. Compared to Control, HFD animals have shown increased visceral fat (6.0 ± 0.8 vs. 13.8 ± 0.6g/100g BW), impaired endothelial dependent vasodilatation, decreased FCD (11.3 ± 1.3 vs. 6.8 ± 1.2/field) and capillary recruitment during hyperinsulinemia and increased macromolecular permeability after ischemia/reperfusion (86.4 ± 5.2 vs.105.2 ± 5.1 leaks/cm(2)), iNOS expression and insulin resistance. MAP, HR, endothelial independent vasodilatation and eNOS expression were not different between groups. Our results have shown that HFD elicits an increase on visceral fat deposition, microvascular dysfunction and insulin resistance in hamsters.

OBJECTIVE -Endothelial dysfunction is an early marker of atherosclerosis seen in type 2 diabetic subjects. Metformin is commonly used in the treatment of type 2 diabetes and has known vasculoprotective effects beyond its hypoglycemic ones. We aimed to investigate the vascular effects of metformin in first-degree relatives with metabolic syndrome of type 2 diabetic patients.RESEARCH DESIGN AND METHODS -The study included 31 subjects (age 38.3 Ϯ 7.6 years and BMI 36.3 Ϯ 5.2 kg/m 2 ), who were first-degree relatives of type 2 diabetic patients and who had metabolic syndrome and normal glucose tolerance. The subjects were randomly assigned 1:1 in a double-blind fashion to receive placebo (n ϭ 15) or metformin (n ϭ 16). Endothelial function was assessed by venous occlusion plethysmography, measuring forearm blood flow (FBF) and vascular resistance responses to three intra-arterial infusions of endothelium-dependent (acetylcholine 7.5, 15, and 30 g/min) and independent (sodium nitroprusside 2, 4, and 8 g/min) vasodilators. Weight, BMI, systolic and diastolic blood pressure, waist, and laboratory parameters (lipid profile and fasting plasma glucose [FPG]) were assessed at baseline and after treatment.RESULTS -The metformin and placebo groups did not differ in anthropometric, clinical, laboratory, and vascular measurements at baseline. The metformin group had decreased weight, BMI, systolic blood pressure, and FPG and improved lipid profile. Endothelium-dependent FBF responses were also improved, without any effect on endothelium-independent responses. There was no correlation between the improvement on FBF responses and the observed changes on anthropometric, clinical, and laboratory parameters.CONCLUSIONS -We concluded that metformin improved vascular endothelial reactivity in first-degree relatives with metabolic syndrome of type 2 diabetic patients, independently of its known antihyperglycemic effects. Diabetes Care 29:1083-1089, 2006T he precocious and accelerated atherosclerosis seen in type 2 diabetes raised the question about pathogenetic factors that initiate the development of vascular derangements in the prediabetic population. Metabolic syndrome, a pre-diabetic state, comprises an array of cardiovascular risk factors such as abdominal obesity, dyslipidemia, hypertension, impaired glucose tolerance, and insulin resistance. Insulin resistance, the central abnormality for the pathogenesis of metabolic syndrome, is considered an independent risk factor for cardiovascular mortality in general (1) and in the diabetic population (2) in particular.The endothelium is an important locus for the control of vascular function. It actively regulates vascular tone, permeability to leukocytes and macromolecules, the balance between coagulation and fibrinolysis, composition of the subendothelial matrix, and proliferation of vascular smooth muscle cells. The great variety of beneficial functions attributed to the endothelium is mainly associated with nitric oxide (NO) bioavailability. In experimental studies of atherogenesis,...