Association between adiponectin and endothelial dysfunction

Abstract

OBJECTIVE: Adiponectin is an adipocyte-specific plasma protein and recent evidence suggests that adiponectin may have an antiatherogenic effect by reducing endothelial activation. This study was performed to investigate whether plasma adiponectin levels were related to endothelial dysfunction in patients with or without type 2 diabetes. METHODS: 73 patients with type 2 diabetes and 73 matched controls of similar age and body mass index were recruited. Plasma adiponectin level was determined by an in-house RIA assay, using a rabbit polyclonal antibody against adiponectin. Endothelium-dependent and independent vasodilation of the brachial artery was measured by high resolution vascular ultrasound. RESULTS: Plasma adiponectin level was reduced in the diabetic patients compared to controls (4.73 ± 1.96 µg/ml vs 7.69 ± 2.80 respectively, p < 0.001). Both endothelium-dependent (5.6 ± 3.6% vs 8.6 ± 4.5 respectively, p<0.001) and independent (13.3 ± 4.9% vs 16.5 ± 5.6 respectively, p < 0.001) vasodilation were impaired in the diabetic patients. On univariate analysis, plasma adiponectin levels correlated with endothelium-dependent vasodilation in the controls (r=0.26, p=0.02) and in the diabetic patients (r=0.24, p=0.04) whereas no significant relationship with endothelium-independent vasodilation was found. On multiple linear regression analysis, only gender, HbA1c and plasma adiponectin level were significant independent determinants of endothelium-dependent vasodilation. CONCLUSION: Low plasma adiponectin level is associated with impaired endothelium-dependent vasodilation in subjects with or without type 2 diabetes. In addition to its role in glucose metabolism, adiponectin may act as a link between adipose tissue and the vasculature.