Objectives: Nitric oxide, NO, is the key vasorelaxing agent produced by vascular endothelium. Stable end products of NO oxidation, nitrate and nitrite (NOx), are considered as markers of endothelial dysfunction associated with hypertension. Our goal was to compare NOx levels in patients with hypertension on controlled low nitrate diet with NOx levels in general population without dietary restrictions.
Patients and methods: The study included 1005 participants split into 8 groups: healthy subjects (n=28) and patients with moderate (n=37) and malignant hypertension (n=24) on low nitrate diet; healthy subjects (n=9) and patients with stroke (n=44) on low nitrate diet; normotensive subjects (n=354) and patients with elevated blood pressure (n=430) and severe hypertension (n=79) without dietary restrictions.
Results: In groups with controlled low NOx diet, patients with moderate and malignant hypertension had significantly (p<0.01) higher serum NOx versus healthy subject (66.9±18.8μM and 75.3±22.7μM versus 52.8±28.8μM, respectively). Patients with stroke had significantly (p=0.02) higher serum NOx levels versus corresponding group of healthy subjects (106.3±58.4μM versus 71.2±18.1μM, respectively). In the absence of dietary control, differences in serum NOx levels between normotensive subjects and patients with elevated blood pressure and severe hypertension were not significant (p>0.1).
Conclusion: Differences in serum NOx concentrations are associated with severity of hypertension only in patients on low nitrate diet. The highest concentrations of NOx were observed in patients with stroke. In the absence of dietary control, NOx levels were not associated with presence or severity of hypertension.
Keywords: Hypertension; Low nitrate/nitrite diet; NOx; Nitric oxide; Serum nitrate; Serum nitrite; Stroke.
Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.