Central Haemodynamics, Baroreceptor Sensitivity and Alpha1-Adrenoceptor-Mediated Vascular Reactivity During Weight-Stable Sodium Restriction in Obese Men with Hypertension

Abstract
Ten obese men (20-40% overweight) with previously untreated arterial hypertension (WHO stages I and II) were examined before and during sodium-restricted isocaloric diets. The mean (± s.d.) daily sodium excretion was reduced from 199 ± 65 to 65 ± 25 mmol/24 h. Intra-arterial blood pressure (BP), cardiac output (CO), plasma volume, circulating and urinary noradrenaline (NA), plasma renin activity (PRA) and urinary aldosterone were measured. Vascular reactivity was assessed with intravenous bolus injections of 50, 100 and 200 µg phenylephrine, and baroreflex sensitivity was assessed with the R-R interval response to pressure elevations on electrocardiogram. Significant reductions in systolic BP from 163 ± 18 to 147 ± 17 mmHg and in diastolic BP from 97 ± 7 to 88 ± 9 mmHg occurred during salt restriction. Blood pressure reductions were correlated with changes of urinary sodium excretion (r=0.71; P