Lymphocyte beta-adrenergic receptors in young subjects with peripheral or central obesity: relationship with central haemodynamics and left ventricular function

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Abstract
This study was designed to evaluate total (t) and surface (s) β-adrenergic receptor (BAR) density and their relationship with central haemodynamics and left ventricular function in young subjects with central or peripheral obesity. A total of 31 obese subjects (BMI ≥30.5 kg. m−2 for males and >27.3 kg. m−2 for females) aged less than 40 years and without other risk factors for cardiovascular diseases (smoking, hypertension, diabetes and lipid abnormalities) were studied. Nine had peripheral obesity and 22 central obesity according to WHR values; there were 20 lean controls (BMI −2 for males and −2 for females). Casual (c) and 24 h ambulatory mean blood pressures (MBP-24 h) were determined. BAR density was evaluated according to Böyum and De Blasi methods Plasma catecholamines by high perfusion liquid chromatography and fasting immunoreactive plasma insulin (IRI) were also measured by RIA. Radionuclide angiocardiography was used to determine central haemodynamics and both systolic and diastolic left ventricular function. Total peripheral resistances (TPR) and intravascular volumes were also determined. Echocardio-graphic study was used to measure LVM, LVM. h−1, LVDD and IVS. Left ventricular ejection fraction (LVEF), peak filling rate (PFR), BARt and BARs were significantly lower (P−1 and time to PFR significantly higher (P<0.05) in both obese groups than in lean controls. Plasma IRI was significantly (P<0.05) higher in both obese groups whereas plasma norepinephrine was higher only in central obese. Comparisons between the two obese groups indicated that only LVEF was significantly lower (P<0.05) in subjects with central obesity than in subjects with peripheral obesity. BARt and BARs correlated inversely with BMI, SV, LVDD and total blood volume. Multiple regression analysis indicated that BMI and SV remained the best predictors of BAR measurement even when epinephrine, IRI and MBP-24 h values were considered. These results indicate that obese subjects have signs of hyperkinetic circulation and depressed lymphocyte BAR densities.