Association between reduced lymphocyte beta-adrenergic receptors and left ventricular dysfunction in young obese subjects

Abstract

This study was designed to evaluate total (t) and surface (s) beta-adrenergic receptors (BAR) density and their relationships with left ventricular function in young obese subjects. BAR density, plasma insulin, catecholamines and left ventricular function were evaluated in 27 young obese subjects (BMI > 30.5 kg/m2 for males and > 27.3 kg/m2 for females) without other risk factors for cardiovascular diseases (smoking, hypertension, diabetes and lipid abnormalities) and in 20 lean controls (BMI < 25 kg/m2 for males and < 24.7 kg/m2 for females). Both groups were matched for gender, age and body height. BAR density was evaluated according to Böyum and De Blasi methods. Plasma catecholamines by high perfusion liquid chromatography and fasting immunoreactive plasma insulin (IRI) levels by RIA were also measured. Casual (c) and 24 h ambulatory mean blood pressure (MBP/24h) were determined. Radionuclide angiocardiography was used to measure left ventricular ejection fraction (LVEF), peak filling rate (PFR), time to PFR (tPFR), cardiac output (CO) and stroke volume (SV). Total left ventricular mass (LVM), indexed for height (LVM/H), left ventricular diastolic dimension (LVDD) and interventricular septal (IVS) thickness by echocardio-graphic study were calculated. LVEF, PFR, BARt, BARs were significantly lower (P < 0.0001) and plasma IRI, CO, SV (P < 0.0001), LVM (P < 0.003), LVM/H (P < 0.004), LVDD (P < 0.02) and tPFR (P < 0.02) were significantly higher in obese subjects than in lean controls. BARt and BARs correlated inversely with BMI, SV and LVDD.