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Background and Purpose: Reduced renal blood flow triggers activation of the renin‐angiotensin‐aldosterone system (RAAS) leading to renovascular hypertension. Renal vascular smooth muscle expression of the NO receptor, soluble GC (sGC), modulates the vasodilator response needed to control renal vascular tone and blood flow. Here, we tested if angiotensin II (Ang II) affects sGC expression via an AT1 receptor‐forkhead box subclass O (FoxO) transcription factor dependent mechanism. Experimental Approach Using a murine two‐kidney‐one‐clip (2K1C) renovascular hypertension model, we measured renal artery vasodilatory function and sGC expression. Additionally, we conducted cell culture studies using rat renal pre‐glomerular smooth muscle cells (RPGSMCs) to test the in vitro mechanistic effects of Ang II treatment on sGC expression and downstream function. Key Results: Contralateral, unclipped renal arteries in 2K1C mice showed increased NO‐dependent vasorelaxation compared to sham control mice. Immunofluorescence studies revealed increased sGC protein expression in 2K1C contralateral renal arteries over sham controls. RPGSMCs treated with Ang II caused a significant up‐regulation of sGC mRNA and protein expression as well as downstream sGC‐dependent signalling. Ang II signalling effects on sGC expression occurred through an AT1 receptor and FoxO transcription factor‐dependent mechanism at both the mRNA and protein expression levels. Conclusion and Implications: Renal artery smooth muscle, in vivo and in vitro, up‐regulates expression of sGC following RAAS activity. In both cases, up‐regulation of sGC leads to increased downstream cGMP signalling, suggesting a previously unrecognized protective mechanism to improve renal blood flow in the uninjured contralateral renal artery. LINKED ARTICLES: This article is part of a themed issue on cGMP Signalling in Cell Growth and Survival. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v179.11/issuetoc [ABSTRACT FROM AUTHOR]

Renovascular hypertension is characterized by activation of the renin-angiotensinaldosterone system, blunted natriuretic responses, and elevated sympathetic nerve activity. Excess dietary salt intake exaggerates arterial blood pressure (ABP) in multiple models of experimental hypertension. The present study tested whether a high-salt diet exaggerated ABP and vascular dysfunction in a 2-kidney, 1-clip (2K1C) murine model. Male C57BL/6J mice (8 –12 wk) were randomly assigned, and fed a 0.1% or 4.0% NaCl diet, and instrumented with telemetry units to measure ABP. Then, the 2K1C model was produced by placing a cuff around the right renal artery. Systolic, diastolic, and mean ABP were significantly higher in mice fed 4.0% vs. 0.1% NaCl at 1 wk but not after 3 wk. Interestingly, 2K1C hypertension progressively increased arterial pulse pressure in both groups; however, the magnitude was significantly greater in mice fed 4.0% vs. 0.1% NaCl at 3 wk. Moreover, pulse wave velocity was significantly greater in 2K1C mice fed 4.0% vs. 0.1% NaCl diet or sham-operated mice fed either diet. Histological assessment of aortas indicated no structural differences among groups. Finally, endothelium-dependent vasodilation was significantly and selectively attenuated in the aorta but not mesenteric arteries of 2K1C mice fed 4.0% NaCl vs. 0.1% NaCl or shamoperated control mice. The findings suggest that dietary salt loading transiently exaggerates 2K1C renovascular hypertension but promotes chronic aortic stiffness and selective aortic vascular dysfunction. [ABSTRACT FROM AUTHOR]

Background--Collectrin is an orphan member of the renin-angiotensin system and is a homolog of angiotensin-converting enzyme 2, sharing ≈50% sequence identity. Unlike angiotensin-converting enzyme 2, collectrin lacks any catalytic domain. Collectrin has been shown to function as a chaperone of amino acid transporters. In rodents, the renal expression of collectrin is increased after subtotal nephrectomy and during high-salt feeding, raising the question of whether collectrin has any direct role in blood pressure regulation. Methods and Results--Using a susceptible genetic background, we demonstrate that deletion of collectrin results in hypertension, exaggerated salt sensitivity, and impaired pressure natriuresis. Collectrin knockout mice display impaired endothelium-dependent vasorelaxation that is associated with vascular remodeling, endothelial nitric oxide synthase uncoupling, decreased nitric oxide production, and increased superoxide generation. Treatment with Tempol, a superoxide scavenger, attenuates the augmented sodium sensitivity in collectrin knockout mice. We report for the first time that collectrin is expressed in endothelial cells. Furthermore, collectrin directly regulates l-arginine uptake and plasma membrane levels of CAT1 and y+LAT1 amino acid transporters in endothelial cells. Treatment with l-arginine modestly lowers blood pressure of collectrin knockout mice. Conclusions--Collectrin is a consequential link between the transport of l-arginine and endothelial nitric oxide synthase uncoupling in hypertension. [ABSTRACT FROM AUTHOR]