A low-calorie diet improves endothelium-dependent vasodilation in obese patients with essential hypertension

Abstract

Background Both obesity and hypertension are associated with endothelial dysfunction. The purpose of this study was to investigate the effects of a low-calorie diet on endothelial function in obese patients with essential hypertension. Methods We measured forearm blood flow (FBF) during intra-arterial infusion of acetylcholine (ACh; 7.5, 15, 30 μg/min), an index of endothelium-dependent vasodilation, and isosorbide dinitrate (ISDN; 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 on a low-calorie diet (800 kcal/d). The study included 11 obese hypertensive Japanese patients (mean body mass index, 30.8 ± 3.6 kg/m 2). Fifteen healthy Japanese normotensive individuals were recruited as a control group. Results In obese patients with hypertension, the response of FBF to ACh was attenuated compared to healthy individuals ( P < .001). Caloric restriction reduced body weight from 77.5 ± 15.0 to 73.2 ± 13.5 kg ( P < .01), the mean blood pressure from 118.4 ± 8.7 to 105.7 ± 8.5 mm Hg ( P < .01), fasting plasma insulin from 85.8 ± 22.8 to 64.8 ± 27.0 pmol/L ( P < .05), serum total cholesterol from 5.30 ± 0.76 to 4.67 ± 0.58 mmol/L ( P < .05), and low density lipoprotein cholesterol from 3.80 ± 0.48 to 3.29 ± 0.44 mmol/L ( P < .05). Basal FBF was similar before and after weight reduction. Caloric restriction enhanced the response of FBF to ACh ( P < .05), but did not alter the response to ISDN. The intra-arterial infusion of N G-monomethyl- l-arginine (8 μmol/min), a nitric oxide synthase inhibitor, decreased the enhanced ACh-induced blood flow response induced by caloric restriction. Conclusions The present findings suggest that the caloric restriction improves endothelial-dependent vasodilation through an increased release of nitric oxide in obese hypertensive patients.