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

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 flock (FBF) during intra-arterial infusion of acetylcholine (ACh; 7.5, 15, 30 mug/min). an index of endodielium-dependent vasodilation, and isosorbide dinitrate (ISDN, 0.75, 1.5, 3.0 mug/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 as 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 530 +/- 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 mumol/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. Am J Hypertens 2002;15:302-309 (C) 2002 American Journal of Hypertension. Ltd.