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Vascular endothelial dysfunction has been demonstrated in overweight or obese patients, but the molecular basis for this link has not been clarified. We asked what the relationship was between adiponectin, an adipose-specific molecule, and endothelial function. Forearm blood flow (FBF) was measured during reactive hyperemia by using strain-gauge plethysmography in 76 Japanese subjects without a history of cardiovascular or cerebrovascular disease, diabetes mellitus, hepatic, or renal disease. The peak FBF and total reactive hyperemic flow [flow debt repayment (FDR)] during reactive hyperemia were correlated with waist circumference (r = -0.418 and -0.414, respectively) and body mass index (r = -0.597 and -0.626, respectively). After correcting for age, gender, and body mass index, the peak FBF was correlated with systolic blood pressure (r = -0.294; P = 0.010), free fatty acid (FFA) (r = -0.331; P = 0.004), and adiponectin in log 10 (r = 0.492; P < 0.001), and FDR was correlated with adiponectin in log 10 (r = 0.462; P = 0.001). In stepwise multiple regression analyses, predictive variables for peak FBF were adiponectin in log 10 (r = 0.468) and FFA (r = -0.292; r(2) = 0.487; P < 0.0001); and predictive variables for FDR were adiponectin in log 10 (r = 0.474) and FFA (r = -0.275; r(2) = 0.346, P < 0.0001). Endothelial function was impaired in proportion to the severity of obesity, and the level of severity was closely related to plasma adiponectin levels. Adiponectin may play a protective role against the atherosclerotic vascular change, and loss of effects enhances endothelial dysfunction, as in obese people.

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Vascular endothelial dysfunction has been demonstrated in obesity, but the molecular basis for this link has not been clarified. We examined the role of free fatty acids (FFA) on vascular reactivity in the obese fa/fa Zucker diabetic fatty (ZDF) rat. Addition of acetylcholine produced a dose-dependent relaxation in aortic rings of ZDF and lean +/+ rats, but the ED(50) value was higher in ZDF (-6.80 +/- 0.05 vs. -7.11 +/- 0.05 log(10) mol/liter, P = 0.033). A 2-wk treatment with a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, pitavastatin (3 mg/kg/d) or a reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, apocynin (5 mmol/liter in drinking water), improved the response in ZDF (ED(50), -7.16 +/- 0.03 and -7.14 +/- 0.05 log(10) mol/liter, P = 0.008 and P = 0.015 vs. vehicle, respectively). Vasodilator response to sodium nitroprusside was identical between ZDF and +/+ rats. Vascular reactive oxygen species (ROS) levels and NADPH oxidase activity in aorta were increased in ZDF rats but were decreased by pitavastatin. In in vitro cell culture, intracellular ROS signal and NADPH oxidase subunit mRNA were increased by palmitate, but this palmitate-induced ROS production was inhibited by NADPH oxidase inhibitor or pitavastatin. In conclusion, FFA-induced NADPH oxidase subunit overexpression and ROS production could be involved in the endothelial dysfunction seen in obese ZDF rats, and this could be protected by pitavastatin or NADPH oxidase inhibitors.