Impact of Acute Dietary Nitrate Supplementation during Exercise in Hypertensive Women

Introduction the aim of the current investigation was to examine if dietary nitrate supplementation would improve vascular control in hypertensive postmenopausal women (PMW). We tested the hypotheses that acute dietary nitrate supplementation would 1) significantly decrease arterial blood pressure (BP) at rest and during exercise, 2) increase limb blood flow during steady-state (SS) exercise, and 3) improve functional sympatholysis during SS exercise. Methods Ten hypertensive PMW underwent a randomized, double-blind, placebo-controlled trial with a nitrate-rich (NR) or nitrate-poor (NP) supplement. Beat-by-beat BP and heart rate were recorded throughout the trial on the nonexercising limb. Forearm blood flow was measured via ultrasonography on the brachial artery of the exercising limb. All patients performed a resting cold pressor test (CPT) (2 min) and then 7 min of submaximal handgrip exercise with a CPT applied during minutes 5-7. Results SS systolic (NR, 170 +/- 7; NP, 171 +/- 37 mm Hg), diastolic (NR, 89 +/- 2; NP, 92 +/- 2 mm Hg), and mean arterial (NR, 121 +/- 4; NP, 123 +/- 2 mm Hg) pressures were not different between NP and NR treatment conditions (P > 0.05). During SS exercise, forearm blood flow (NR, 189 +/- 8; NP, 218 +/- 8 mL center dot min(-1); P = 0.03) in the NR treatment was significantly lower compared with NP. When the CPT was applied during minutes 6-7 of exercise, forearm vascular conductance was reduced by 15% in the NR condition, but only 7% in the NR condition. Conclusions In summary, an acute NR supplement improved functional sympatholysis by similar to 50% versus an NP placebo condition. Improvements in functional sympatholysis may have important implications regarding exercise tolerance in hypertensive PMW.