Persistent vascular dysfunction following an acute nonpharmacological reduction in blood pressure in hypertensive patients.

Abstract

Vascular dysfunction, an independent risk factor for cardiovascular disease, often persists in patients with hypertension, despite improvements in blood pressure control induced by antihypertensive medications. As some of these medications may directly affect vascular function, this study sought to comprehensively examine the impact of reducing blood pressure, by a nonpharmacological approach (5 days of sodium restriction), on vascular function in 22 hypertensive individuals (14 men/8 women, 50 ± 10 years). Following a 2-week withdrawal of antihypertensive medications, two 5-day dietary phases, liberal sodium (liberal sodium, 200 mmol/day) followed by restricted sodium (restricted sodium, 10 mmol/day), were completed. Resting blood pressure was assessed and vascular function, at both the conduit and microvascular levels, was evaluated by brachial artery flow-mediated dilation (FMD), reactive hyperemia, progressive handgrip exercise, and passive leg movement (PLM). Despite a sodium restriction-induced fall in blood pressure (liberal sodium: 141 ± 14/85 ± 9; restricted sodium 124 ± 12/79 ± 9 mmHg, P < 0.01 for both SBP and DBP), FMD (liberal sodium: 4.6 ± 1.8%; restricted sodium: 5.1 ± 2.1%, P = 0.27), and reactive hyperemia (liberal sodium: 548 ± 201; restricted sodium: 615 ± 206 ml, P = 0.08) were not altered. Similarly, brachial artery vasodilation during handgrip exercise was not different between conditions (liberal sodium: Δ0.36 ± 0.19 mm; restricted sodium: Δ0.42 ± 0.18 mm, P = 0.16). Lastly, PLM-induced changes in peak blood flow (liberal sodium: 5.3 ± 2.5; restricted sodium: 5.8 ± 3.6 ml/min per mmHg, P = 0.30) and the total vasodilatory response [liberal sodium: 2 (0.9-2.5) vs. restricted sodium: 1.7 (1.1-2.6) ml/min per mmHg; P = 0.5] were also not different between conditions. Thus vascular dysfunction, at both the conduit and microvascular levels, persists in patients with hypertension even when blood pressure is acutely reduced by a nonpharmacological approach.