Abstract P545: Insufficient Sleep and Nitric Oxide-Mediated Endothelium-Dependent Vasodilation in Adults With Elevated Blood Pressure

Abstract

Elevated blood pressure (BP ≥130/80 mmHg) is associated with increased risk for myocardial infarction, heart failure, stroke and vascular disease. Insufficient nightly sleep (<7 h/night) has been linked not only to the etiology of elevated blood pressure but is a prevalent, often ignored, comorbidity. Indeed, short sleep duration is now considered to be a plausible risk factor for elevated blood pressure and a harbinger of increased cardiovascular risk. A high prevalence of insufficient nightly sleep has been reported in adults with elevated blood pressure. The influence of insufficient sleep on endothelial vasodilator function in adults with elevated blood pressure is unknown. We tested the hypotheses that chronic insufficient sleep is associated with diminished nitric oxide (NO)-mediated endothelium-dependent vasodilation in adults with elevated blood pressure. Moreover, the insufficient sleep-related reduction in endothelial vasodilator function is due, at least in part to increased oxidative stress. Thirty-five middle-aged and older adults with elevated blood pressure were studied: 15 with normal nightly sleep duration (11M/4F; age: 58±2 yr; BP: 136/82±1/2 mmHg; sleep: 7.6±0.2 h/night) and 20 with short nightly sleep duration (14M/6F; 58±1 yr; BP: 138/84±1/1 mmHg; sleep: 6.0±0.1 h/night). Forearm blood flow (FBF) responses to intra-arterial infusion of acetylcholine (ACh), in the absence and presence of the endothelial NO synthase inhibitor N G -monomethyl-L-arginine (L-NMMA) and the antioxidant vitamin C were determined by venous occlusion plethysmography. The FBF response to ACh was significantly lower (~20%) in the short sleep (from 3.8±0.2 to 11.0±0.6 ml/100 ml tissue/min) compared with the normal sleep duration group (from 4.2±0.2 to 13.6±0.6 ml/100 ml tissue/min). L-NMMA significantly reduced (~25%) the FBF response to ACh in the normal sleep but not the short sleep group. Vitamin C markedly increased (~35%; P<0.05) the vasodilator response to ACh in short sleepers only. In summary, habitual short sleep duration worsens NO-mediated endothelium-dependent vasodilation in adults with elevated blood pressure. Furthermore, the sleep-related diminishment in endothelial vasodilator function is due, in part, to increased oxidative stress.