scholarly journals Transgenic mice expressing an intracellular fluorescent fusion of angiotensin II demonstrate renal thrombotic microangiopathy and elevated blood pressure

2010 ◽  
Vol 298 (6) ◽  
pp. H1807-H1818 ◽  
Author(s):  
K. M. Redding ◽  
B. L. Chen ◽  
A. Singh ◽  
R. N. Re ◽  
L. G. Navar ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Transgenic Mice ◽  
Fusion Protein ◽  
Thrombotic Microangiopathy ◽  
Fluorescent Imaging ◽  
Elevated Blood Pressure ◽  
Ang Ii ◽  
Elevated Blood ◽  
Wild Type

We have generated transgenic mice that express angiotensin II (ANG II) fused downstream of enhanced cyan fluorescent protein, expression of which is regulated by the mouse metallothionein promoter. The fusion protein, which lacks a secretory signal, is retained intracellularly. In the present study, RT-PCR, immunoblot analyses, whole-animal fluorescent imaging, and fluorescent microscopy of murine embryonic fibroblasts confirm expression of the fusion protein in vivo and in vitro. The transgene is expressed in all tissues tested (including brain, heart, kidney, liver, lung, and testes), and radioimmunoassay of plasma samples obtained from transgenic mice indicate no increase in circulating ANG II over wild-type levels, consistent with intracellular retention of the transgene product. Kidneys from transgenic and corresponding wild-type littermates were histologically evaluated, and abnormalities in transgenic mice consistent with thrombotic microangiopathy were observed; microthrombosis was frequently observed within the glomerular capillaries and small vessels. In addition, systolic and diastolic blood pressures, measured by telemetry ( n = 8 for each group), were significantly higher in transgenic mice compared with wild-type littermates. Blood pressure of line A male transgenic mice was 125 ± 1.7 over 97 ± 1.6 compared with 109 ± 1.7 over 83 ± 1.4 mmHg in wild-type littermates (systolic over diastolic). In summary, overexpression of an intracellular fluorescent fusion protein of ANG II correlates with elevated blood pressure and kidney pathology. This transgenic model may be useful to further explore the intracellular renin-angiotensin system and its implication in abnormal kidney function and hypertension.

scholarly journals Proximal Tubule-Specific Deletion of Angiotensin II Type 1a Receptors in the Kidney Attenuates Circulating and Intratubular Angiotensin II–Induced Hypertension in PT- Agtr1a −/− Mice

Hypertension ◽  
2021 ◽  
Author(s):  
Xiao Chun Li ◽  
Ana Paula Oliveira Leite ◽  
Xiaowen Zheng ◽  
Chunling Zhao ◽  
Xu Chen ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Fusion Protein ◽  
Proximal Tubule ◽  
Proximal Tubules ◽  
Normal Blood ◽  
Ang Ii ◽  
Normal Blood Pressure ◽  
Wild Type ◽  
Induced Hypertension

The present study used a novel mouse model with proximal tubule-specific knockout of AT 1a receptors in the kidney, PT- Agtr1a −/− , to test the hypothesis that intratubular Ang II (angiotensin II) and AT 1a receptors in the proximal tubules are required for maintaining normal blood pressure and the development of Ang II–induced hypertension. Twenty-six groups (n=6–15 per group) of adult male wild-type, global Agtr1a −/− , and PT- Agtr1a −/− mice were infused with Ang II (1.5 mg/kg per day, IP), or overexpressed an intracellular Ang II fusion protein in the proximal tubules for 2 weeks. Basal telemetry blood pressure were ≈15±3 mm Hg lower in PT- Agtr1a −/− than wild-type mice and ≈13±3 mm Hg higher than Agtr1a −/− mice ( P <0.01). Basal glomerular filtration was ≈23.9% higher ( P <0.01), whereas fractional proximal tubule Na + reabsorption was lower in PT- Agtr1a −/− mice ( P <0.01). Deletion of AT 1a receptors in the proximal tubules augmented the pressure-natriuresis response ( P <0.01) and natriuretic responses to salt loading or Ang III infusion ( P <0.01). Ang II induced hypertension in wild-type, PT- Agtr1a −/− and PT- Nhe3 −/− mice, but the pressor response was ≈16±2 mm Hg lower in PT- Agtr1a −/− and PT- Nhe3 −/− mice ( P <0.01). Deletion of AT 1a receptors or NHE3 (Na + /H + exchanger 3) in the proximal tubules attenuated ≈50% of Ang II–induced hypertension in wild-type mice ( P <0.01), but blocked intracellular Ang II fusion protein-induced hypertension in PT- Agtr1a −/− mice ( P <0.01). Taken together, the results of the present study provide new insights into the critical role of intratubular Ang II/AT 1 (AT 1a )/NHE3 pathways in the proximal tubules in normal blood pressure control and the development of Ang II–induced hypertension.

scholarly journals Renal Natriuretic Peptide Receptor-C Deficiency Attenuates NaCl Cotransporter Activity in Angiotensin II–Induced Hypertension

Hypertension ◽  
2021 ◽  
Vol 77 (3) ◽  
pp. 868-881
Author(s):  
Shuai Shao ◽  
Xiao-Dong Li ◽  
Yuan-Yuan Lu ◽  
Shi-Jin Li ◽  
Xiao-Hui Chen ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Natriuretic Peptide ◽  
Elevated Blood Pressure ◽  
Natriuretic Peptide Receptor ◽  
Sodium Retention ◽  
Ang Ii ◽  
Elevated Blood ◽  
Peptide Receptor ◽  
Induced Hypertension

Genome-wide association studies have identified that NPR-C (natriuretic peptide receptor-C) variants are associated with elevation of blood pressure. However, the mechanism underlying the relationship between NPR-C and blood pressure regulation remains elusive. Here, we investigate whether NPR-C regulates Ang II (angiotensin II)-induced hypertension through sodium transporters activity. Wild-type mice responded to continuous Ang II infusion with an increased renal NPR-C expression. Global NPR-C deficiency attenuated Ang II–induced increased blood pressure both in male and female mice associated with more diuretic and natriuretic responses to a saline challenge. Interestingly, Ang II increased both total and phosphorylation of NCC (NaCl cotransporter) abundance involving in activation of WNK4 (with-no-lysine kinase 4)/SPAK (Ste20-related proline/alanine-rich kinase) which was blunted by NPR-C deletion. NCC inhibitor, hydrochlorothiazide, failed to induce natriuresis in NPR-C knockout mice. Moreover, low-salt and high-salt diets–induced changes of total and phosphorylation of NCC expression were normalized by NPR-C deletion. Importantly, tubule-specific deletion of NPR-C also attenuated Ang II–induced elevated blood pressure, total and phosphorylation of NCC expression. Mechanistically, in distal convoluted tubule cells, Ang II dose and time-dependently upregulated WNK4/SPAK/NCC kinase pathway and NPR-C/Gi/PLC/PKC signaling pathway mediated NCC activation. These results demonstrate that NPR-C signaling regulates NCC function contributing to sodium retention-mediated elevated blood pressure, which suggests that NPR-C is a promising candidate for the treatment of sodium retention-related hypertension.

The elevated blood pressure of humanGRK4γA142Vtransgenic mice is not associated with increased ROS production

2007 ◽  
Vol 292 (5) ◽  
pp. H2083-H2092 ◽  
Author(s):  
Zheng Wang ◽  
Ines Armando ◽  
Laureano D. Asico ◽  
Crisanto Escano ◽  
Xiaoyan Wang ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Transgenic Mice ◽  
Urinary Excretion ◽  
Hypotensive Effect ◽  
Elevated Blood Pressure ◽  
Ros Production ◽  
Elevated Blood ◽  
Wild Type ◽  
Mixed Genetic Background ◽  
Blood Pressures

G protein-coupled receptor (GPCR) kinases (GRKs) regulate the sensitivity of GPCRs, including dopamine receptors. The GRK4 locus is linked to, and some of its polymorphisms are associated with, human essential hypertension. Transgenic mice overexpressing human (h) GRK4γ A142V on a mixed genetic background (C57BL/6J and SJL/J) have impaired renal D1-dopamine receptor (D1R) function and increased blood pressure. We now report that hGRK4γ A142V transgenic mice, in C57BL/6J background, are hypertensive and have higher blood pressures than hGRK4γ wild-type transgenic and nontransgenic mice. The hypertensive phenotype is stable because blood pressures in transgenic founders and F6 offspring are similarly increased. To determine whether the hypertension is associated with increased production of reactive oxygen species (ROS), we measured renal NADPH oxidase (Nox2 and Nox4) and heme oxygenase (HO-1 and HO-2) protein expressions and urinary excretion of 8-isoprostane and compared the effect of Tempol on blood pressure in hGRK4γ A142V transgenic mice and D5R knockout (D5−/−) mice in which hypertension is mediated by increased ROS. The expressions of Nox isoforms and HO-2 and the urinary excretion of 8-isoprostane were similar in hGRK4γ A142V transgenic mice and their controls. HO-1 expression was increased in hGRK4γ A142V relative to hGRK4γ wild-type transgenic mice. In contrast with the hypotensive effect of Tempol in D5−/−mice, it had no effect in hGRK4γ A142V transgenic mice. We conclude that the elevated blood pressure of hGRK4γ A142V transgenic mice is due mainly to the effect of hGRK4γ A142V transgene acting via D1R and increased ROS production is not a contributor.

Abstract 065: Overexpression of an Intracellular Angiotensin II Fusion Protein Selectively in the Mitochondria of the Proximal Tubules Elevates Blood Pressure in Mice via AT 1a Receptor-mediated Mitochondrial Respiratory and Glycolysis Stress

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Xiao C Li ◽  
Manoocher Soleimani ◽  
Hoang Nguyen ◽  
Hong Li ◽  
Jia L Zhuo
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Fusion Protein ◽  
Proximal Tubule ◽  
Physiological Role ◽  
Proximal Tubules ◽  
Ang Ii ◽  
Stress Tests ◽  
Arterial Blood ◽  
Mitochondrial Respiratory

An intracrine mitochondrial renin-angiotensin system (RAS) has recently been identified in various animal and human tissues, but whether the mitochondrial RAS plays a physiological role in the regulation of blood pressure remains unknown. The present study tested whether overexpression of an intracellular angiotensin II fusion protein, ECFP/ANG II, selectively in the mitochondria of the proximal tubules alters blood pressure, and whether the effects may involve AT 1a receptors and the Na + /H + exchanger 3 (NHE3). An adenoviral vector encoding ECFP/ANG II, a mitochondria targeting sequence, and the sglt2 promoter, Ad-sglt2-mito-ECFP/ANG II, was constructed for proximal tubule- and mitochondria-specific overexpression for 2 weeks. In adult male C57BL/6J mice, overexpression of mito-ECFP/ANG II in the mitochondria of the proximal tubules increased systolic blood pressure (SBP) significantly (Control: 116 ± 3 vs. mito-ECFP/ANG II: 128 ± 3 mmHg; p <0.01, n=15). The blood pressure-increasing effect of Ad-sglt2-mito-ECFP/ANG II was blocked in proximal tubule-specific AT 1a -KO mice (Control: 105 ± 2 vs. mito-ECFP/ANG II: 104 ± 4 mmHg; n.s ., n=7), or in proximal tubule-specific NHE3-KO mice (Control: 108 ± 3 vs. mito-ECFP/ANG II: 107 ± 3 mmHg; n.s ., n=13), respectively. In further experiments, mouse proximal tubule cells were transfected with Ad-sglt2-mito-ECFP/ANG II for 48 h and treated with the AT 1 blocker losartan (10 μM) or the AT 2 blocker PD123319 (10 μM) to measure mitochondrial respiratory and glycolytic function using Seahorse XF Cell Mito and XF Glycolysis Stress Tests. The mito-ECFP/ANG II expression was robust and colocalized with MitoTracker® Red FM. Overexpression of mito-ECFP/ANG II markedly increased oxygen consumption rate (OCR) (Control: 139.4 ± 9.2 vs. mito-ECFP/ANG II: 236.3 ± 12.6 pmol/min; p <0.01, n=12) and extracellular acidification rate (ECAR) (Control: 8.8 ± 0.6 vs. mito-ECFP/ANG II: 11.8 ± 1.2 mpH/min; p <0.01, n=12), respectively. Losartan blocked the effects of mito-ECFP/ANG II on OCR and ECAR, whereas PD123319 had no effect. We conclude that intracellular ANG II may activate AT 1 receptors in the mitochondria of the proximal tubules to alter mitochondrial respiratory and glycolytic function and arterial blood pressure.

Angiotensin II promotes aortic valve thickening independent of elevated blood pressure in apolipoprotein-E deficient mice

2013 ◽  
Vol 226 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Tomohiro Fujisaka ◽  
Masaaki Hoshiga ◽  
Junko Hotchi ◽  
Yoshihiro Takeda ◽  
Denan Jin ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Aortic Valve ◽  
Apolipoprotein E ◽  
Elevated Blood Pressure ◽  
Elevated Blood ◽  
Deficient Mice

scholarly journals The effects of phentolamine on fructose-fed rats

2012 ◽  
Vol 90 (8) ◽  
pp. 1075-1085 ◽  
Author(s):  
Kangbin Zhou ◽  
Ujendra Kumar ◽  
Violet G. Yuen ◽  
John H. McNeill
Keyword(s):  
Blood Pressure ◽  
Uric Acid ◽  
Angiotensin Ii ◽  
Plasma Levels ◽  
Elevated Blood Pressure ◽  
Elevated Blood ◽  
Medical Disorders ◽  
Dietary Fructose ◽  
Plasma Nitrate

Metabolic syndrome (MS) is a combination of medical disorders that increase the risk of developing cardiovascular disease and diabetes. MS is associated with obesity, increased blood pressure, hyperlipidemia, and hyperglycemia. This study was designed to investigate the pharmacological profile of phentolamine, a nonselective α adrenergic receptor antagonist, in the prevention of increased blood pressure in fructose-fed rats. Phentolamine prevented the fructose-induced increase in systolic blood pressure without affecting insulin sensitivity and major metabolic parameters. The levels of plasma noradrenaline and angiotensin II, 2 proposed contributors to the development of fructose-induced elevated blood pressure, were examined. Neither noradrenaline nor angiotensin II levels were affected by phentolamine treatment. Since overproduction of nitric oxide has been shown to lead to an elevation in peroxynitrite, the role of oxidative stress, a proposed mechanism of fructose-induced elevated blood pressure and insulin resistance, was examined by measuring plasma levels of total nitrate/nitrite. Plasma nitrate/nitrite was significantly elevated in all fructose-fed animals, regardless of treatment with phentolamine. Another proposed contributor toward fructose-induced MS is an elevation in uric acid levels. In this experiment, plasma levels of uric acid were found to be increased by dietary fructose and were unaffected by phentolamine treatment.

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