Abstract 28: Regular Aerobic Exercise Counteracts Endothelial Vasomotor Dysfunction Associated With Insufficient Sleep

Abstract

Insufficient sleep, defined as chronic short sleep duration (<7 h/night), is an independent risk factor for cardiovascular disease (CVD). We have previously demonstrated that insufficient sleep is associated with reduced endothelium-dependent vasodilation and enhanced endothelin (ET)-1-mediated vasoconstrictor tone. Impaired endothelial vasomotor regulation is thought to contribute mechanistically to the increased risk of atherosclerotic vascular disease incurred with chronic insufficient sleep. Regular aerobic exercise is an effective lifestyle strategy for improving endothelial function and, in turn reducing cardiovascular risk. It is currently unknown if regular aerobic exercise can counteract the negative impact of insufficient sleep on endothelial vasomotor regulation. We tested the hypotheses that regular aerobic exercise would: 1) improve endothelial vasodilation; and 2) decrease ET-1-mediated vasoconstrictor tone in middle-aged adults who chronically sleep less than 7 h/night. We studied 36 healthy, middle-aged adults: 16 with normal sleep duration (10M/6F; age: 57±2 yr; sleep duration: 7.4±0.1 h/night) and 20 with short sleep duration (11M/9F; 56±1 yr; sleep duration: 6.2±0.1 h/night). The 20 short sleepers completed a 3-month aerobic exercise training intervention. Forearm blood flow (FBF; plethysmography) was determined in response to intra-arterial doses of acetylcholine (ACh), sodium nitroprusside (SNP), BQ-123 (ET A receptor antagonist) and ACh + BQ-123 in both groups and after the exercise intervention in the short sleepers. As expected, forearm vasodilator responses to ACh were lower (20%; P<0.05) in the short (from 4.2±0.2 to 10.5±0.6 mL/100 mL tissue/min) vs normal (4.2±0.2 to 12.7±0.6 mL/100 mL tissue/min) sleepers. FBF responses to SNP were comparable between the groups. In response to BQ-123, short sleep group had a greater increase in resting FBF than normal sleep group (~25% vs ~8%; P< 0.05). ACh+BQ-123 resulted in an ~25% increase in the ACh-vasodilation in the short sleep group only. After exercise training, although nightly sleep duration was not affected (6.4±0.1 h/night), ACh-mediated vasodilation was ~20% higher (P<0.05), ET-1-mediated vasoconstriction was ~90% lower (P<0.05) and vasodilator response to ACh was not significantly increased with ET A receptor blockade. These results indicate that regular aerobic exercise can reverse the negative influence of insufficient sleep on endothelial vasomotor function, independent of changes in nightly sleep duration.