A Low-Calorie Diet Improves Endothelium-Dependent Vasodilation in Obese Patients with Essential Hypertension
Objective: This study investigated the effects of a low-calorie diet on endothelial function in obese patients with essential hypertension. Methods: We measured forearm blood flow during intraarterial infusion of acetylcholine (7.5, 15, 30 μg/min, an index of endothelium-dependent vasodilation) and isosorbide dinitrate (0.75, 1.5, 3.0 μg/min, an index of endothelium-independent vasodilation) in obese patients with essential hypertension before and after 2-weeks of the low-calorie diet (800 Kcal/d). The study included 11 obese hypertensive Japanese patients (mean body mass index: 30.8 ± 3.6 kg/m2). Fifteen healthy Japanese normotensive individuals were recruited as a control group. Results: In obese patients with hypertension, the response of forearm blood flow to acetylcholine was attenuated compared to healthy individuals (P<0.001). Caloric restriction reduced body weight from 77.5±15.0 to 73.2±13.5 kg (P<0.01), the mean blood pressure from 118.4±8.7 to 105.7±8.5 mm Hg (P<0.01), fasting plasma insulin from 85.8±22.8 to 64.8±27.0 pmol/L (P<0.05), serum total cholesterol from 5.30±0.76 to 4.67±0.58 mmol/L (P<0.05), and low density lipoprotein cholesterol from 3.80±0.48 to 3.29±0.44 mmol/L (P<0.05). Basal forearm blood flow was similar before and after weight loss. Caloric restriction enhanced the response of forearm blood flow to acetylcholine (P<0.05), but did not alter the response to isosorbide dinitrate. The intraarterial infusion of NG-monomethyl-L-arginine (8 μmol/min, a nitric oxide synthase inhibitor) decreased the enhanced acetylcholine-induced blood flow response induced by caloric restriction. Conclusion: The present findings suggest that weight loss with caloric restriction improves endothelial-dependent vasodilation through an increased release of nitric oxide in obese hypertensive patients.