scholarly journals Sensitivity of NOS-dependent vascular relaxation pathway to mineralocorticoid receptor blockade in caveolin-1-deficient mice

2010 ◽  
Vol 298 (6) ◽  
pp. H1776-H1788 ◽  
Author(s):  
Luminita H. Pojoga ◽  
Zuzana Adamová ◽  
Abhinav Kumar ◽  
Amanda K. Stennett ◽  
Jose R. Romero ◽  
...  
Keyword(s):  
Vascular Function ◽  
Mineralocorticoid Receptor ◽  
Vascular Reactivity ◽  
Steroid Receptors ◽  
Inhibitory Effect ◽  
Vascular Relaxation ◽  
Enos Expression ◽  
Western Blots ◽  
Caveolin 1 ◽  
Deficient Mice

Endothelial caveolin-1 (cav-1) is an anchoring protein in plasma membrane caveolae where it binds endothelial nitric oxide synthase (eNOS) and limits its activation, particularly in animals fed a high salt (HS) diet. Cav-1 also interacts with steroid receptors such as the mineralocorticoid receptor (MR). To test the hypothesis that vascular reactivity is influenced by an interplay between MR and cav-1 during HS diet, we examined the effects of MR blockade on NOS-mediated vascular relaxation in normal and cav-1-deficient mice. Wild-type (WT) and cav-1 knockout mice (cav-1−/−) were fed for 14 days a HS (4% NaCl) diet with and without the MR antagonist eplerenone (Epl; 100 mg·kg−1·day−1). After systolic blood pressure (BP) was measured, the thoracic aorta was isolated for measurement of vascular reactivity, and the aorta and heart were used for measurement of eNOS and MR expression. BP was not different between WT + Epl and WT, but was higher in cav-1−/− + Epl than in cav-1−/− mice. Phenylephrine (Phe)-induced vascular contraction was less in cav-1−/− than WT, and significantly enhanced in cav-1−/− + Epl than in cav-1−/−, but not in WT + Epl compared with WT. Endothelium removal and NOS blockade by Nω-nitro-l-arginine methyl ester (l-NAME) enhanced Phe contraction in cav-1−/−, but not cav-1−/− + Epl. ACh-induced aortic relaxation was reduced in cav-1−/− + Epl versus cav-1−/−, but not in WT + Epl compared with WT. Endothelium removal, l-NAME, and the guanylate cyclase inhibitor ODQ abolished the large ACh-induced relaxation in cav-1−/− and the remaining relaxation in the cav-1−/− + Epl but had similar inhibitory effect in WT and WT + Epl. Real-time RT-PCR indicated decreased eNOS mRNA expression in the aorta and heart, and Western blots revealed decreased total eNOS in the heart of cav-1−/− + Epl compared with cav-1−/−. Vascular and cardiac MR expression was less in cav-1−/− than WT, but not in cav-1−/− + Epl compared with cav-1−/−. Plasma aldosterone (Aldo) was not different between WT and cav-1−/− mice nontreated or treated with Epl. Thus in cav-1 deficiency states and HS diet MR blockade is associated with increased BP, enhanced vasoconstriction, and decreased NOS-mediated vascular relaxation and eNOS expression. The data suggest that, in the absence of cav-1, MR activation plays a beneficial role in regulating eNOS expression/activity and, consequently, the vascular function during HS diet.

scholarly journals Effect of dietary sodium on vasoconstriction and eNOS-mediated vascular relaxation in caveolin-1-deficient mice

2008 ◽  
Vol 294 (3) ◽  
pp. H1258-H1265 ◽  
Author(s):  
Luminita H. Pojoga ◽  
Tham M. Yao ◽  
Sumi Sinha ◽  
Reagan L. Ross ◽  
Jeffery C. Lin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Blood Pressure ◽  
Vascular Function ◽  
Sodium Intake ◽  
Dietary Sodium ◽  
Vascular Relaxation ◽  
Enos Expression ◽  
Vascular Contraction ◽  
Caveolin 1 ◽  
Enos Activity

Changes in dietary sodium intake are associated with changes in vascular volume and reactivity that may be mediated, in part, by alterations in endothelial nitric oxide synthase (eNOS) activity. Caveolin-1 (Cav-1), a transmembrane anchoring protein in the plasma membrane caveolae, binds eNOS and limits its translocation and activation. To test the hypothesis that endothelial Cav-1 participates in the dietary sodium-mediated effects on vascular function, we assessed vascular responses and nitric oxide (NO)-mediated mechanisms of vascular relaxation in Cav-1 knockout mice (Cav-1−/−) and wild-type control mice (WT; Cav-1+/+) placed on a high-salt (HS; 4% NaCl) or low-salt (LS; 0.08% NaCl) diet for 16 days. After the systolic blood pressure was measured, the thoracic aorta was isolated for measurement of vascular reactivity and NO production, and the heart was used for measurement of eNOS expression and/or activity. The blood pressure was elevated in HS mice treated with NG-nitro-l-arginine methyl ester and more so in Cav-1−/− than WT mice and was significantly reduced during the LS diet. Phenylephrine caused vascular contraction that was significantly reduced in Cav-1−/− (maximum 0.25 ± 0.06 g/mg) compared with WT (0.75 ± 0.22 g/mg) on the HS diet, and the differences were eliminated with the LS diet. Also, vascular contraction in response to membrane depolarization by high KCl (96 mM) was reduced in Cav-1−/− (0.27 ± 0.05 g/mg) compared with WT mice (0.53 ± 0.12 g/mg) on the HS diet, suggesting that the reduced vascular contraction is not limited to a particular receptor. Acetylcholine (10−5 M) caused aortic relaxation in WT mice on HS (23.6 ± 3.5%) and LS (23.7 ± 5.5%) that was enhanced in Cav-1−/− HS (72.6 ± 6.1%) and more so in Cav-1−/− LS mice (93.6 ± 3.5%). RT-PCR analysis indicated increased eNOS mRNA expression in the aorta and heart, and Western blots indicated increased total eNOS and phosphorylated eNOS in the heart of Cav-1−/− compared with WT mice on the HS diet, and the genotypic differences were less apparent during the LS diet. Thus Cav-1 deficiency during the HS diet is associated with decreased vasoconstriction, increased vascular relaxation, and increased eNOS expression and activity, and these effects are altered during the LS diet. The data support the hypothesis that endothelial Cav-1, likely through an effect on eNOS activity, plays a prominent role in the regulation of vascular function during substantial changes in dietary sodium intake.

scholarly journals Restoring placental growth factor-soluble fms-like tyrosine kinase-1 balance reverses vascular hyper-reactivity and hypertension in pregnancy

2016 ◽  
Vol 311 (3) ◽  
pp. R505-R521 ◽  
Author(s):  
Minglin Zhu ◽  
Zongli Ren ◽  
José S. Possomato-Vieira ◽  
Raouf A. Khalil
Keyword(s):  
Growth Factor ◽  
Tyrosine Kinase ◽  
Vascular Function ◽  
Vascular Reactivity ◽  
Placental Growth Factor ◽  
Hypertensive Disorder ◽  
Vascular Relaxation ◽  
No Donor ◽  
Western Blots ◽  
Nitrite Production

Preeclampsia (PE) is a pregnancy-related hypertensive disorder (HTN-Preg) with unclear mechanism. An imbalance between antiangiogenic soluble fms-like tyrosine kinase-1 (sFlt-1) and angiogenic placental growth factor (PlGF) has been observed in PE, but the vascular targets and signaling pathways involved are unclear. We assessed the extent of sFlt-1/PlGF imbalance and vascular dysfunction in a rat model of HTN-Preg produced by reduction of uteroplacental perfusion pressure (RUPP), and tested whether inducing a comparable sFlt-1/PlGF imbalance by infusing sFlt-1 (10 μg·kg−1·day−1) in day 14 pregnant (Preg) rats cause similar increases in blood pressure (BP) and vascular reactivity. Using these guiding measurements, we then tested whether restoring sFlt-1/PlGF balance by infusing PIGF (20 μg·kg−1·day−1) in RUPP rats would improve BP and vascular function. On gestational day 19, BP was in Preg+sFlt-1 and RUPP > Preg, and in RUPP+PlGF < RUPP rats. Plasma sFlt-1/PlGF ratio was increased in Preg+sFlt-1, and RUPP and was reduced in RUPP+PlGF rats. In isolated endothelium-intact aorta, carotid, mesenteric, and renal artery, phenylephrine (Phe)- and high KCl-induced contraction was in Preg+sFlt-1 and RUPP > Preg, and in RUPP+PlGF < RUPP. The differences in vascular reactivity to Phe and KCl between groups were less apparent in vessels treated with the nitric oxide synthase (NOS) inhibitor l-NAME or guanylate cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) or endothelium-denuded, suggesting changes in endothelial NO-cGMP pathway. In Phe precontracted vessels, ACh-induced relaxation was in Preg+sFlt-1 and RUPP < Preg, and in RUPP+PlGF > RUPP, and was blocked by Nω-nitro-l-arginine methyl ester (l-NAME) or ODQ treatment or endothelium removal. Western blots revealed that aortic total endothelial NOS (eNOS) and activated phosphorylated-eNOS were in Preg+sFlt-1 and RUPP < Preg and in RUPP+PlGF > RUPP. ACh-induced vascular nitrate/nitrite production was in Preg+sFlt-1 and RUPP < Preg, and in RUPP+PlGF > RUPP. Vascular relaxation to the exogenous NO donor sodium nitroprusside was not different among groups. Thus, a tilt in the angiogenic balance toward anti-angiogenic sFlt-1 is associated with decreased vascular relaxation and increased vasoconstriction and BP. Restoring the angiogenic/antiangiogenic balance using PlGF enhances endothelial NO-cGMP vascular relaxation and decreases vasoconstriction and BP in HTN-Preg rats and could offer a new approach in the management of PE.

scholarly journals Vascular phenotype of amyloid precursor protein-deficient mice

2019 ◽  
Vol 316 (6) ◽  
pp. H1297-H1308
Author(s):  
Livius V. d’Uscio ◽  
Zvonimir S. Katusic
Keyword(s):  
Amyloid Precursor Protein ◽  
Vascular Function ◽  
Vascular Reactivity ◽  
Amine Oxidase ◽  
Precursor Protein ◽  
Guanosine Monophosphate ◽  
Vasomotor Function ◽  
Vascular Phenotype ◽  
Circulating Levels ◽  
Deficient Mice

The amyloid precursor protein (APP) is expressed in the blood vessel wall, but the physiological function of APP is not completely understood. Previous studies established that APP has amine oxidase activity responsible for degradation of catecholamines. In the present study, we characterized the vascular phenotype of APP-knockout (APP−/−) mice. We demonstrate that circulating levels of catecholamines are significantly increased in male as compared with female APP−/− mice. Studies of vasomotor function in isolated aortas revealed that contractions to the α1-receptor agonist phenylephrine were significantly reduced in male APP−/− mice but not in females. In addition, contractions to G protein activation with sodium fluoride were reduced exclusively in male APP−/− mice aortas. The endothelium-dependent relaxations to acetylcholine were not affected by the loss of APP in mice of both sexes. Further analysis of the mechanisms underlying endothelium-dependent relaxations revealed that inhibition of cyclooxygenase by indomethacin significantly impaired relaxations to acetylcholine exclusively in male APP−/− mice. Furthermore, acetylcholine-induced production of cyclic guanosine monophosphate (cGMP) was significantly reduced in male APP−/− mice aortas while acetylcholine-induced production of cyclic adenosine monophosphate (cAMP) was enhanced. We concluded that altered vascular reactivity to phenylephrine appears to be in part the result of chronic exposure of male APP−/− aorta to high circulating levels of catecholamines. The mechanisms responsible for the impairment of endothelium-dependent cGMP signaling and adaptive enhancement of endothelium-dependent production of cAMP remain to be defined. NEW & NOTEWORTHY Male amyloid precursor protein (APP)-deficient mice have higher circulating levels of catecholamines as compared with female APP-deficient mice. As a consequence, endothelium-dependent and endothelium-independent vasomotor functions of male APP-deficient mice are significantly altered. Under physiological conditions, expression of APP appears to play an important role in vascular function.

scholarly journals Contractile and Endothelium-Dependent Dilatory Responses of Cerebral Arteries at Various Extracellular Magnesium Concentrations

1991 ◽  
Vol 11 (1) ◽  
pp. 161-164 ◽  
Author(s):  
Mária Faragó ◽  
Csaba Szabó ◽  
Eörs Dóra ◽  
Ildikó Horváth ◽  
Arisztid G. B. Kovách
Keyword(s):  
Smooth Muscle ◽  
Vascular Reactivity ◽  
Calcium Influx ◽  
Cerebral Arteries ◽  
Inhibitory Effect ◽  
Contractile Responses ◽  
Middle Cerebral Arteries ◽  
The Right ◽  
Endothelial Receptor

To clarify the effect of extracellular magnesium (Mg2+) on the vascular reactivity of feline isolated middle cerebral arteries, the effects of slight alterations in the Mg2+ concentration on the contractile and endothelium-dependent dilatory responses were investigated in vitro. The contractions, induced by 10−8-10−5 M norepinephrine, were significantly potentiated at low Mg2+ (0.8 m M v. the normal, 1.2 m M). High (1.6 and 2.0 m M) Mg2+ exhibited an inhibitory effect on the contractile responses. No significant changes, however, in the EC50 values for norepinephrine were found. The endothelium-dependent relaxations induced by 108–10−5 M acetylcholine were inhibited by high (1.6 and 2.0 m M) Mg2+. Lowering of the Mg2+ concentration to 0.8 m M or total withdrawal of this ion from the medium failed to alter the dilatory potency of acetylcholine. The changes in the dilatory responses also shifted the EC50 values for acetylcholine to the right. The present results show that the contractile responses of the cerebral arteries are extremely susceptible to the changes of Mg2+ concentrations. In response to contractile and endothelium-dependent dilatory agonists, Mg2+ probably affects both the calcium influx into the endothelial and smooth muscle cells as well as the binding of acetylcholine to its endothelial receptor. Since Mg2+ deficiency might facilitate the contractile but not the endothelium-dependent relaxant responses, the present study supports a role for Mg2+ deficiency in the development of the cerebral vasospasm.

scholarly journals Altered V-ATPase expression in renal intercalated cells isolated from B1 subunit-deficient mice by fluorescence-activated cell sorting

2013 ◽  
Vol 304 (5) ◽  
pp. F522-F532 ◽  
Author(s):  
Luca Vedovelli ◽  
John T. Rothermel ◽  
Karin E. Finberg ◽  
Carsten A. Wagner ◽  
Anie Azroyan ◽  
...  
Keyword(s):  
Cell Sorting ◽  
Collecting Duct ◽  
Egfp Expression ◽  
Intercalated Cells ◽  
Wild Type ◽  
Western Blots ◽  
Atpase Subunit ◽  
Protein Levels ◽  
Baseline Conditions ◽  
Deficient Mice

Unlike human patients with mutations in the 56-kDa B1 subunit isoform of the vacuolar proton-pumping ATPase (V-ATPase), B1-deficient mice (Atp6v1b1−/−) do not develop metabolic acidosis under baseline conditions. This is due to the insertion of V-ATPases containing the alternative B2 subunit isoform into the apical membrane of renal medullary collecting duct intercalated cells (ICs). We previously reported that quantitative Western blots (WBs) from whole kidneys showed similar B2 protein levels in Atp6v1b1−/− and wild-type mice (Păunescu TG, Russo LM, Da Silva N, Kovacikova J, Mohebbi N, Van Hoek AN, McKee M, Wagner CA, Breton S, Brown D. Am J Physiol Renal Physiol 293: F1915–F1926, 2007). However, WBs from renal medulla (including outer and inner medulla) membrane and cytosol fractions reveal a decrease in the levels of the ubiquitous V-ATPase E1 subunit. To compare V-ATPase expression specifically in ICs from wild-type and Atp6v1b1−/− mice, we crossed mice in which EGFP expression is driven by the B1 subunit promoter (EGFP-B1+/+ mice) with Atp6v1b1−/− mice to generate novel EGFP-B1−/− mice. We isolated pure IC populations by fluorescence-assisted cell sorting from EGFP-B1+/+ and EGFP-B1−/− mice to compare their V-ATPase subunit protein levels. We report that V-ATPase A, E1, and H subunits are all significantly downregulated in EGFP-B1−/− mice, while the B2 protein level is considerably increased in these animals. We conclude that under baseline conditions B2 upregulation compensates for the lack of B1 and is sufficient to maintain basal acid-base homeostasis, even when other V-ATPase subunits are downregulated.

Abstract 2474: Rho-Kinase Inhibition Improves Endothelium-Dependent Vasodilation during Hyperinsulinemia in Patients with Metabolic Syndrome

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Francesca Schinzari ◽  
Manfredi Tesauro ◽  
Valentina Rovella ◽  
Augusto Veneziani ◽  
Nadia Mores ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Metabolic Syndrome ◽  
Vascular Function ◽  
Vascular Reactivity ◽  
Rho Kinase ◽  
Serine Phosphorylation ◽  
No Donor ◽  
Kinase Inhibition ◽  
Impaired Insulin

Impaired insulin-mediated vasodilation in the skeletal muscle may be involved in the development of hypertension in patients with metabolic syndrome (MetS) and contribute to insulin resistance by diminishing the glucose uptake. Rho-kinase, an effector of the small G protein Rho A, plays an important role in hypertension and is reported to interfere with insulin signaling through serine phosphorylation of insulin receptor substrate-1 in blood vessels. We therefore examined the role of Rho-kinase in the pathophysiology of impaired vascular reactivity in patients with MetS by evaluating the effect of Rho-kinase inhibition on NO-dependent vasodilation during hyperinsulinemia. Forearm blood flow (FBF) responses to acetylcholine (ACh), a stimulus for endothelial release of NO, and sodium nitroprusside (SNP), an exogenous NO donor, were assessed during insulin administration (0.1 mU/Kg/min) using the forearm perfusion technique in patients with MetS (n=10) and matched controls (n=10). Patients with MetS were then randomized to intra-arterial infusion of either fasudil (inhibitor of Rho-kinase, 200 μg/min) or placebo and reactivity to ACh and SNP was reassessed. During hyperinsulinemia, vasodilator responses to both ACh and SNP were blunted in patients with MetS (both P>0.001 vs. controls). In patients who received fasudil, its administration did not change unstimulated FBF (P=0.75 vs. insulin alone); the vasodilator response to ACh, however, was significantly enhanced by fasudil (P=0.009 vs. insulin alone), while the response to SNP was not significantly changed (P=0.56). In patients with MetS who received placebo, vascular reactivity to both ACh and SNP was not different than before (both P>0.05). In conclusion, Rho-kinase inhibition during hyperinsulinemia improves endothelium-dependent vasodilator responsiveness in patients with MetS. This suggests that, under those conditions, intravascular activation of Rho-kinase is involved in the pathophysiology of endothelial dysfunction and may constitute a critical mediator linking metabolic and hemodynamic abnormalities in insulin resistance. As a consequence, targeting Rho-kinase might beneficially impact both vascular function and insulin sensitivity in patients with MetS.

scholarly journals Lipoprotein-associated phospholipase A2 (Lp-PLA2) as a therapeutic target to prevent retinal vasopermeability during diabetes

2016 ◽  
Vol 113 (26) ◽  
pp. 7213-7218 ◽  
Author(s):  
Paul Canning ◽  
Bridget-Ann Kenny ◽  
Vivien Prise ◽  
Josephine Glenn ◽  
Mosharraf H. Sarker ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Vascular Function ◽  
Specific Inhibitor ◽  
Inhibitory Effect ◽  
Diabetic Rats ◽  
Brown Norway ◽  
Vegf Receptor ◽  
Blood Retinal Barrier ◽  
Species Specific ◽  
Brb Breakdown

Lipoprotein-associated phospholipase A2 (Lp-PLA2) hydrolyses oxidized low-density lipoproteins into proinflammatory products, which can have detrimental effects on vascular function. As a specific inhibitor of Lp-PLA2, darapladib has been shown to be protective against atherogenesis and vascular leakage in diabetic and hypercholesterolemic animal models. This study has investigated whether Lp-PLA2 and its major enzymatic product, lysophosphatidylcholine (LPC), are involved in blood–retinal barrier (BRB) damage during diabetic retinopathy. We assessed BRB protection in diabetic rats through use of species-specific analogs of darapladib. Systemic Lp-PLA2 inhibition using SB-435495 at 10 mg/kg (i.p.) effectively suppressed BRB breakdown in streptozotocin-diabetic Brown Norway rats. This inhibitory effect was comparable to intravitreal VEGF neutralization, and the protection against BRB dysfunction was additive when both targets were inhibited simultaneously. Mechanistic studies in primary brain and retinal microvascular endothelial cells, as well as occluded rat pial microvessels, showed that luminal but not abluminal LPC potently induced permeability, and that this required signaling by the VEGF receptor 2 (VEGFR2). Taken together, this study demonstrates that Lp-PLA2 inhibition can effectively prevent diabetes-mediated BRB dysfunction and that LPC impacts on the retinal vascular endothelium to induce vasopermeability via VEGFR2. Thus, Lp-PLA2 may be a useful therapeutic target for patients with diabetic macular edema (DME), perhaps in combination with currently administered anti-VEGF agents.

scholarly journals Caveolin-1-Deficient Mice Show Defects in Innate Immunity and Inflammatory Immune Response during Salmonella enterica Serovar Typhimurium Infection

2006 ◽  
Vol 74 (12) ◽  
pp. 6665-6674 ◽  
Author(s):  
Freddy A. Medina ◽  
Cecilia J. de Almeida ◽  
Elliott Dew ◽  
Jiangwei Li ◽  
Gloria Bonuccelli ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Salmonella Enterica ◽  
Inflammatory Responses ◽  
Systemic Infection ◽  
Bacterial Invasion ◽  
Chemokine Production ◽  
Caveolin 1 ◽  
Serovar Typhimurium ◽  
Deficient Mice

ABSTRACT A number of studies have shown an association of pathogens with caveolae. To this date, however, there are no studies showing a role for caveolin-1 in modulating immune responses against pathogens. Interestingly, expression of caveolin-1 has been shown to occur in a regulated manner in immune cells in response to lipopolysaccharide (LPS). Here, we sought to determine the role of caveolin-1 (Cav-1) expression in Salmonella pathogenesis. Cav-1−/− mice displayed a significant decrease in survival when challenged with Salmonella enterica serovar Typhimurium. Spleen and tissue burdens were significantly higher in Cav-1−/− mice. However, infection of Cav-1−/− macrophages with serovar Typhimurium did not result in differences in bacterial invasion. In addition, Cav-1−/− mice displayed increased production of inflammatory cytokines, chemokines, and nitric oxide. Regardless of this, Cav-1−/− mice were unable to control the systemic infection of Salmonella. The increased chemokine production in Cav-1−/− mice resulted in greater infiltration of neutrophils into granulomas but did not alter the number of granulomas present. This was accompanied by increased necrosis in the liver. However, Cav-1−/− macrophages displayed increased inflammatory responses and increased nitric oxide production in vitro in response to Salmonella LPS. These results show that caveolin-1 plays a key role in regulating anti-inflammatory responses in macrophages. Taken together, these data suggest that the increased production of toxic mediators from macrophages lacking caveolin-1 is likely to be responsible for the marked susceptibility of caveolin-1-deficient mice to S. enterica serovar Typhimurium.

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