Abstract P183: Influence of Insufficient Sleep on Endothelial Fibrinolytic Capacity in Adults With Elevated Blood Pressure

Abstract

The capacity of the endothelium to release tissue-type plasminogen activator (t-PA) is impaired in adults with elevated BP, leading to an increased risk of thrombotic events. Insufficient sleep is independently associated with elevated BP and impaired t-PA release. However, the compounded influence of insufficient sleep on t-PA release in adults with elevated BP is unknown. We tested the hypothesis that impairments in the capacity of the endothelium to release t-PA in adults with elevated BP is worse in those who sleep <7 h/night (short sleep duration) compared with those who sleep 7 to 9 h/night (normal sleep duration). We studied 38 sedentary, middle-aged adults: 10 with normal BP and normal nightly sleep duration (6M/4F; age: 55±2 yr; BP: 114/94±2/3 mmHg, sleep duration: 7.4±0.2 h); 14 with elevated BP and normal nightly sleep duration (8M/6F; 60±2 yr; 141/87±2/2 mmHg; 7.8±0.1 h); and 14 with elevated BP and short nightly sleep duration (10M/4F; 57±2 yr; 139/85±2/2 mmHg; 6.1±0.2 h). All subjects were free of overt metabolic and coronary disease. Net endothelial release of t-PA was determined, in vivo, in response to intra-brachial infusions of bradykinin (BK: 125-500 ng/min) and sodium nitroprusside (SNP: 2.0-8.0 μg/min). In the normal sleep groups, as expected, endothelial t-PA release in response to BK was significantly blunted (~30%) in the adults with elevated BP (from -1.2±0.8 to 50.2±4.8 ng/100mL tissue/min) compared with normal BP (from 0.9±3.4 to 73.0±8.0 ng/100mL tissue/min); and total t-PA release (area under the BK curve) was ~25% lower (p<0.05) in the adults with elevated (307±33 ng/100mL tissue) vs. normal (396±27 ng/100mL tissue) BP. Importantly, net endothelial release rate (from -1.5±1.0 to 40.6±4.3 ng/100mL tissue/min) and total amount of t-PA released (222±28 ng/100mL tissue) in response to BK were markedly lower (~25% and 30%, respectively, P<0.05) in the elevated BP and short sleep duration group compared with the elevated BP and normal sleep duration group. In the elevated BP population, sleep duration was positively correlated with total t-PA release (r=0.46, P<0.05). There was no effect of SNP on t-PA release in any group. In summary, insufficient sleep is associated with exacerbated impairments in t-PA release in adults with elevated BP.