Nitro-Oleic Acid Inhibits Angiotensin II–Induced Hypertension

Abstract

RATIONALE: Nitro-oleic acid (OA-NO(2)) is a bioactive, nitric-oxide derived fatty acid with physiologically relevant vasculoprotective properties in vivo. OA-NO(2) exerts cell signaling actions as a result of its strong electrophilic nature and mediates pleiotropic cell responses in the vasculature. OBJECTIVE: The present study sought to investigate the protective role of OA-NO(2) in angiotensin (Ang) II-induced hypertension. METHODS AND RESULTS: We show that systemic administration of OA-NO(2) results in a sustained reduction of Ang II-induced hypertension in mice and exerts a significant blood pressure lowering effect on preexisting hypertension established by Ang II infusion. OA-NO(2) significantly inhibits Ang II contractile response as compared to oleic acid (OA) in mesenteric vessels. The improved vasoconstriction is specific for the Ang II type 1 receptor (AT(1)R)-mediated signaling because vascular contraction by other G-protein-coupled receptors is not altered in response to OA-NO(2) treatment. From the mechanistic viewpoint, OA-NO(2) lowers Ang II-induced hypertension independently of peroxisome proliferation-activated receptor (PPAR)gamma activation. Rather, OA-NO(2), but not OA, specifically binds to the AT(1)R, reduces heterotrimeric G-protein coupling, and inhibits IP(3) (inositol-1,4,5-trisphosphate) and calcium mobilization, without inhibiting Ang II binding to the receptor. CONCLUSIONS: These results demonstrate that OA-NO(2) diminishes the pressor response to Ang II and inhibits AT(1)R-dependent vasoconstriction, revealing OA-NO(2) as a novel antagonist of Ang II-induced hypertension.