Plasma 8-isoprostane levels are associated with endothelial dysfunction in resistant hypertension

Background: Impaired endothelial function and arterial stiffness are associated with hypertension and are important risk factors for cardiovascular events. Reactive oxygen species reduce nitric oxide bioavailability and have a pivotal role in endothelial function. Resistant hypertension (RHTN) is characterized by blood pressure (BP) above goal (140/90 mmHg) in spite of the concurrent use of >= 3 antihypertensive drugs of different classes. This study evaluated the association between 8-isoprostane levels, an oxidative stress marker, endothelial function and arterial stiffness, in RHTN. Methods: Ninety-four RHTN and 55 well-controlled hypertensive (HT) patients were included. Plasma 8-isoprostane levels were determined by ELISA. Also, flow-mediated dilation (FMD) and pulse wave velocity (PWV) were evaluated to determine endothelial function and arterial stiffness, respectively. Results: Levels of 8-isoprostane were markedly higher in RHTN compared to HT patients (22.5 +/- 11.2 vs. 17.3 +/- 9.8 pg/ml, p < 0.05, respectively). A significant inverse correlation was observed between FMD and 8-isoprostane (r = -0.35, p = 0.001) in RHTN. Finally, multiple logistic regression revealed that 8-isoprostane was a significant predictor of endothelial dysfunction (FMD <= median) in RHTN group. Conclusion: RHTN showed markedly higher oxidative stress measured by 8-isoprostane, compared to HT patients. Taken together, our findings suggest the involvement of oxidative stress in endothelial function in RHTN. (C) 2014 Elsevier B.V. All rights reserved.