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

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.

early diagnosis of the hemodynamic regulation disorders in orthostasis

The article deals with the informative content of spectral analysis of heart rate variability in the assessment of the regulatory impacts on the systemic hemodynamics during orthostatic test. It was observed that the patients who suffer from neurogenic syncope already at a young age had had a decrease in low frequency oscillations, as well as a decrease in peripheral vascular resistance during the test. It allows us to make a conclusion about the sympathetic vasomotor regulation dysfunction, even before the symptoms of orthostatic hypotension were evident. The decrease in the tonic vagal effect which follows from the depression of high-frequency oscillations, makes for increasing the chronotropic function of the heart and keeps a relative sympathetic predominance in order to maintain adequate level of blood pressure

Endothelin-1 vasoconstriction and the age-related decline in endothelium-dependent vasodilatation in men

ET (endothelin)-1, a potent vasoconstrictor peptide released by the endothelium, plays an important role in vasomotor regulation and has been linked to diminished endothelial vasodilator capacity in several pathologies associated with human aging, including hypertension, Type 2 diabetes and coronary artery disease. However, it is currently unknown whether the decline in endothelial vasodilatation with advancing age is due to elevated ET-1 vasconstrictor activity. Accordingly, we tested the hypothesis that the age-related impairment in ACh (acetylcholine)-mediated endothelium-dependent vasodilatation is due, at least in part, to increased ET-1-mediated vasoconstrictor tone. FBF (forearm blood flow) responses to ACh, SNP (sodium nitroprusside) and BQ-123 (ETA receptor blocker) were determined in 14 young (age, 25±1 years) and 14 older (age, 61±2 years) healthy non-obese men. Additionally, FBF responses to ACh were determined in the presence of ETA blockade. Vasodilatation to ACh was lower (approx. 25%; P<0.05) in the older men (from 4.9±0.2 to 13.9±0.9 ml·100 ml−1 of tissue·min−1) compared with the young men (4.6±0.3 to 17.2±1.0 ml·100 ml−1 of tissue·min−1). There were no differences in FBF responses to SNP between the young (4.8±0.3 to 18.5±0.3 ml·100 ml−1 of tissue·min−1) and older (5.1±0.3 to 17.3±0.8 ml·100 ml−1 of tissue·min−1) men. In the young men, resting FBF was not significantly altered by BQ-123, whereas, in the older men, FBF increased approx. 25% in response to BQ-123 infusion (P<0.05). Co-infusion of ACh with BQ-123 resulted in an approx. 20% increase in the ACh-induced vasodilatation in older men compared with saline. In contrast, FBF responses to ACh were not significantly altered by ETA blockade in the young men. In conclusion, these results demonstrate that ET-1 vasoconstrictor activity contributes, at least in part, to diminished endothelium-dependent vasodilatation in older men.