Changes in overall plasma norepinephrine turnover and lymphomonocyte beta-adrenoceptor number during combined caloric and sodium restriction in normotensive obese subjects

The aim of the study was to evaluate in eight normotensive obese patients the influence of low sodium intake (9 mEq/day) on the sympathetic activity modifications induced by caloric restriction (2511 kJ/day). As compared to the isocaloric salt balanced diet, 7 days of normosodic underfeeding induced a decrease in the overall norepinephrine turnover (clearance and appearance rate) and 24 hours urinary output, whereas the combined caloric and salt restriction significantly increased the norepinephrine appearance rate and even more the norepinephrine clearance but, on the other hand, decreased the beta-adrenergic receptor number on the lymphomonocyte surface, suggesting a reduced peripheral sensitivity to catecholamines. Therefore, the utility of the combined sodium and caloric restriction in the treatment of the normotensive obese patients remains still questionable.