['Obesity is associated with chronic inflammation due to overproduction of proinflammatory cytokines, including tumor necrosis factor (TNF)-alpha. We assessed the effects of TNF-alpha neutralization by infliximab on vascular reactivity during hyperinsulinemia in obesity-related metabolic syndrome.', 'Vascular responses to intra-arterial infusion of acetylcholine (ACh) and sodium nitroprusside (SNP) were assessed in patients with metabolic syndrome, before and after administration of infliximab.', 'Patients had blunted vasodilator responses to ACh and SNP during hyperinsulinemia compared with control subjects; a potentiation of the responsiveness to both ACh and SNP, however, was observed in patients following infliximab. The antioxidant vitamin C improved the vasodilator response to ACh in patients with metabolic syndrome, but its effect was not further enhanced by concurrent administration of infliximab.'] Does tumor necrosis factor-alpha antagonism improve vasodilation during hyperinsulinemia in metabolic syndrome?