Neuroadrenergic and reflex abnormalities in patients with metabolic syndrome

Aims/hypothesis: Previous studies have shown that alterations in vascular, metabolic, inflammatory and haemocoagulative functions characterise the metabolic syndrome. Whether this is also the case for sympathetic function is not clear. We therefore aimed to clarify this issue and to determine whether metabolic or reflex mechanisms might be responsible for the possible adrenergic dysfunction. Methods: In 43 healthy control subjects (age 48.2±1.0 years, mean±SEM) and in 48 untreated age-matched subjects with metabolic syndrome (National Cholesterol Education Program's Adult Treatment Panel III Report criteria) we measured, along with anthropometric and metabolic variables, blood pressure (Finapres), heart rate (ECG) and efferent postganglionic muscle sympathetic nerve activity (microneurography) at rest and during baroreceptor manipulation (vasoactive drug infusion technique). Results: Compared with control subjects, subjects with metabolic syndrome had higher BMI, waist circumference, blood pressure, cholesterol, triglycerides, insulin and homeostasis model assessment (HOMA) index values but lower HDL cholesterol values. Sympathetic nerve traffic was significantly greater in subjects with metabolic syndrome than in control subjects (61.1±2.6 vs 43.8±2.8 bursts/100 heartbeats, p