NADPH oxidase in the renal microvasculature is a primary target for blood pressure-lowering effects by inorganic nitrate and nitrite

Xiang Gao; Ting Yang; Ming Liu; Maria Peleli; Christa Zollbrecht; Eddie Weitzberg; Jon O Lundberg; A Erik G Persson; Mattias Carlström

doi:10.1161/HYPERTENSIONAHA.114.04222

NADPH oxidase in the renal microvasculature is a primary target for blood pressure-lowering effects by inorganic nitrate and nitrite

Hypertension. 2015 Jan;65(1):161-70. doi: 10.1161/HYPERTENSIONAHA.114.04222. Epub 2014 Oct 13.

Authors

Xiang Gao¹, Ting Yang¹, Ming Liu¹, Maria Peleli¹, Christa Zollbrecht¹, Eddie Weitzberg¹, Jon O Lundberg¹, A Erik G Persson¹, Mattias Carlström²

Affiliations

¹ From the Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden (X.G., A.E.G.P.); and Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (T.Y., M.L., M.P., C.Z., E.W., J.O.L., M.C.).
² From the Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden (X.G., A.E.G.P.); and Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden (T.Y., M.L., M.P., C.Z., E.W., J.O.L., M.C.). mattias.carlstrom@ki.se.

PMID: 25312440
DOI: 10.1161/HYPERTENSIONAHA.114.04222

Abstract

Renal oxidative stress and nitric oxide (NO) deficiency are key events in hypertension. Stimulation of a nitrate-nitrite-NO pathway with dietary nitrate reduces blood pressure, but the mechanisms or target organ are not clear. We investigated the hypothesis that inorganic nitrate and nitrite attenuate reactivity of renal microcirculation and blood pressure responses to angiotensin II (ANG II) by modulating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity and NO bioavailability. Nitrite in the physiological range (10(-7)-10(-5) mol/L) dilated isolated perfused renal afferent arterioles, which were associated with increased NO. Contractions to ANG II (34%) and simultaneous NO synthase inhibition (56%) were attenuated by nitrite (18% and 26%). In a model of oxidative stress (superoxide dismutase-1 knockouts), abnormal ANG II-mediated arteriolar contractions (90%) were normalized by nitrite (44%). Mechanistically, effects of nitrite were abolished by NO scavenger and xanthine oxidase inhibitor, but only partially attenuated by inhibiting soluble guanylyl cyclase. Inhibition of NADPH oxidase with apocynin attenuated ANG II-induced contractility (35%) similar to that of nitrite. In the presence of nitrite, no further effect of apocynin was observed, suggesting NADPH oxidase as a possible target. In preglomerular vascular smooth muscle cells and kidney cortex, nitrite reduced both basal and ANG II-induced NADPH oxidase activity. These effects of nitrite were also abolished by xanthine oxidase inhibition. Moreover, supplementation with dietary nitrate (10(-2) mol/L) reduced renal NADPH oxidase activity and attenuated ANG II-mediated arteriolar contractions and hypertension (99±2-146±2 mm Hg) compared with placebo (100±3-168±3 mm Hg). In conclusion, these novel findings position NADPH oxidase in the renal microvasculature as a prime target for blood pressure-lowering effects of inorganic nitrate and nitrite.

Keywords: angiotension II; hypertension, renovascular; kidney; microcirculation; nitrates; nitric oxide; oxidative stress.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Blood Pressure / drug effects*
Disease Models, Animal
Hypertension / drug therapy
Hypertension / enzymology*
Hypertension / physiopathology
Kidney / blood supply*
Male
Mice
Mice, Inbred C57BL
Microvessels / embryology*
Microvessels / pathology
NADPH Oxidases / biosynthesis*
Nitrates / pharmacology*
Nitrites / pharmacology*
Oxidative Stress

Substances

Nitrates
Nitrites
NADPH Oxidases