P-450 Metabolites of Arachidonic Acid in the Control of Cardiovascular Function

2002 ◽  
Vol 82 (1) ◽  
pp. 131-185 ◽  
Author(s):  
Richard J. Roman
Keyword(s):  
Arachidonic Acid ◽  
Angiotensin Ii ◽  
Vascular Tone ◽  
Mesangial Cells ◽  
Cardiovascular Function ◽  
Tubuloglomerular Feedback ◽  
Peripheral Vasculature ◽  
Therapeutic Benefits

Recent studies have indicated that arachidonic acid is primarily metabolized by cytochrome P-450 (CYP) enzymes in the brain, lung, kidney, and peripheral vasculature to 20-hydroxyeicosatetraenoic acid (20-HETE) and epoxyeicosatrienoic acids (EETs) and that these compounds play critical roles in the regulation of renal, pulmonary, and cardiac function and vascular tone. EETs are endothelium-derived vasodilators that hyperpolarize vascular smooth muscle (VSM) cells by activating K+channels. 20-HETE is a vasoconstrictor produced in VSM cells that reduces the open-state probability of Ca2+-activated K+channels. Inhibitors of the formation of 20-HETE block the myogenic response of renal, cerebral, and skeletal muscle arterioles in vitro and autoregulation of renal and cerebral blood flow in vivo. They also block tubuloglomerular feedback responses in vivo and the vasoconstrictor response to elevations in tissue Po2both in vivo and in vitro. The formation of 20-HETE in VSM is stimulated by angiotensin II and endothelin and is inhibited by nitric oxide (NO) and carbon monoxide (CO). Blockade of the formation of 20-HETE attenuates the vascular responses to angiotensin II, endothelin, norepinephrine, NO, and CO. In the kidney, EETs and 20-HETE are produced in the proximal tubule and the thick ascending loop of Henle. They regulate Na+transport in these nephron segments. 20-HETE also contributes to the mitogenic effects of a variety of growth factors in VSM, renal epithelial, and mesangial cells. The production of EETs and 20-HETE is altered in experimental and genetic models of hypertension, diabetes, uremia, toxemia of pregnancy, and hepatorenal syndrome. Given the importance of this pathway in the control of cardiovascular function, it is likely that CYP metabolites of arachidonic acid contribute to the changes in renal function and vascular tone associated with some of these conditions and that drugs that modify the formation and/or actions of EETs and 20-HETE may have therapeutic benefits.

scholarly journals Smad3 mediates ANG II-induced hypertensive kidney disease in mice

2012 ◽  
Vol 302 (8) ◽  
pp. F986-F997 ◽  
Author(s):  
Zhen Liu ◽  
Xiao R. Huang ◽  
Hui Y. Lan
Keyword(s):  
Angiotensin Ii ◽  
Renal Fibrosis ◽  
Transforming Growth Factor ◽  
Mesangial Cells ◽  
Type I ◽  
Hypertensive Nephropathy ◽  
Renal Inflammation ◽  
Monocyte Chemoattractant Protein 1

Although Smad3 is a key mediator for fibrosis, its functional role and mechanisms in hypertensive nephropathy remain largely unclear. This was examined in the present study in a mouse model of hypertension induced in Smad3 knockout (KO) and wild-type (WT) mice by subcutaneous angiotensin II infusion and in vitro in mesangial cells lacking Smad3. After angiotensin II infusion, both Smad3 KO and WT mice developed equally high levels of blood pressure. However, disruption of Smad3 prevented angiotensin II-induced kidney injury by lowering albuminuria and serum creatinine ( P < 0.01), inhibiting renal fibrosis such as collagen type I and IV, fibronectin, and α-SMA expression (all P < 0.01), and blocking renal inflammation including macrophage and T cell infiltration and upregulation of IL-1β, TNF-α, and monocyte chemoattractant protein-1 in vivo and in vitro (all P < 0.001). Further studies revealed that blockade of angiotensin II-induced renal transforming growth factor (TGF)-β1 expression and inhibition of Smurf2-mediated degradation of renal Smad7 are mechanisms by which Smad3 KO mice were protected from angiotensin II-induced renal fibrosis and NF-κB-driven renal inflammation in vivo and in vitro. In conclusion, Smad3 is a key mediator of hypertensive nephropathy. Smad3 promotes Smurf2-dependent ubiquitin degradation of renal Smad7, thereby enhancing angiotensin II-induced TGF-β/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation. Results from this study suggest that inhibition of Smad3 or overexpression of Smad7 may be a novel therapeutic strategy for hypertensive nephropathy.

scholarly journals Endothelium-derived relaxing factor, nitric oxide: effects on and production by mesangial cells and the glomerulus.

1993 ◽  
Vol 3 (8) ◽  
pp. 1435-1441
Author(s):  
L Raij ◽  
P J Shultz
Keyword(s):  
Nitric Oxide ◽  
Vascular Tone ◽  
Mesangial Cell ◽  
Mesangial Cells ◽  
Glomerular Mesangial Cells ◽  
Relaxing Factor ◽  
Endothelium Derived Relaxing Factor

The endothelium-derived relaxing factor nitric oxide (EDRF/NO) is a labile, endogenous vasodilator that is important in the control of systemic vascular tone. This review focuses on the effects of EDRF/NO on glomerular mesangial cells in vitro and on the role of EDRF/NO in mesangial and glomerular physiology and pathophysiology in vivo. It was concluded that EDRF/NO can stimulate increases in cGMP, inhibit mesangial cell contraction, and inhibit growth factor-induced proliferation of mesangial cells in culture. Furthermore, incubation with endotoxin or cytokines stimulates mesangial cells to produce EDRF/NO, via an inducible NO synthase enzyme. Therefore, it is likely that NO could play a role in the inflammatory response within the glomerulus. Finally, recent studies providing evidence that EDRF/NO is functional within the glomerulus in vivo, especially during endotoxemia and inflammation are also reviewed.

scholarly journals Five-lipoxygenase products in glomerular immune injury.

1992 ◽  
Vol 3 (4) ◽  
pp. 907-915
Author(s):  
K F Badr
Keyword(s):  
Arachidonic Acid ◽  
Structural Damage ◽  
Mesangial Cells ◽  
Significant Degree ◽  
Glomerular Mesangial Cells ◽  
Inflammatory Reactions ◽  
Structural Deterioration ◽  
Immune Injury

Leukocyte infiltration, proliferation, and activation are central pathogenetic components of immune injury in the glomerulus. Initial cellular infiltration by polymorphonuclear leukocytes (PMN) is a consequence of the deposition of immune complexes at discreet sites in the glomerulus. This is often followed by macrophage/monocyte infiltration, as well as proliferation of resident mesangial macrophages. Activated leukocytes constitute a rich source of lipid-derived bioactive autacoids, in particular, oxygenated metabolites of arachidonic acid. Here, we assess the role of the five-lipoxygenase (5-LO) family of eicosanoids, in particular, leukotrienes D4 and B4 (LTD4 and LTB4) in mediating functional and structural deterioration during immune inflammatory reactions in the glomerulus. LTD4 and other peptidyl LT appear to play a central role in the reductions in GFR in the acute phases of injury by virtue of their potent vasoactive properties, in particular, their capacity to reduce the glomerular capillary ultrafiltration coefficient, likely through contraction of smooth muscle elements in glomerular mesangial cells. The latter cells possess specific receptors for LTD4 in both humans and rat and contract in vitro when exposed to LTD4 after receptor-mediated activation of phospholipase C. LTB4, a nonvasoconstrictor LT, is released in the early phases of immune injury, likely from leukocyte sources as well as from transcellular metabolism of its precursor, LTA4, by the enzyme LTA4-hydrolase in glomerular mesangial and endothelial cells. LTB4, a potent promoter of PMN attraction, adhesion, and activation exacerbates glomerular functional impairment and structural damage by amplifying PMN-dependent mechanisms of injury. In their totality, 5-LO products of arachidonic acid contribute to the impairment of the normal glomerular filtration and sieving functions that attend acute inflammatory injury in the renal glomerulus and to the subsequent progression of glomerular destruction. This is high-lighted by the significant degree of protection afforded by the selective inhibition of arachidonate 5-LO in vivo in acute and chronic models of experimental glomerulonephritis.

Angiotensin II increases the expression of the transcription factor ETS-1 in mesangial cells

2008 ◽  
Vol 294 (5) ◽  
pp. F1094-F1100 ◽  
Author(s):  
Damien D. Pearse ◽  
Run-Xia Tian ◽  
Jessica Nigro ◽  
Julian B. Iorgulescu ◽  
Leopold Puzis ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Mesangial Cells ◽  
Critical Role ◽  
Ang Ii ◽  
Specific Sequence ◽  
Cox 2

Maladaptive activation of the renin-angiotensin system (RAS) has been shown to play a critical role in the pathogenesis of chronic kidney disease. Reactive oxygen species (ROS) are critical signals for many of the nonhemodynamic effects of angiotensin II (ANG II). We have demonstrated that ANG II increases mesangial and cortical cyclooxygenase-2 (COX-2) expression and activity via NADPH oxidase-derived ROS. The transcription factor ETS-1 (E26 transformation-specific sequence) has been identified as a critical regulator of growth-related responses and inflammation. The present studies were designed to determine: 1) whether ANG II induces ETS-1 expression in vitro in cultured rat mesangial cells and in vivo in rats infused with ANG II; and 2) whether ROS and COX-2 are mediators of ETS-1 induction in response to ANG II. Mesangial cells stimulated with ANG II (10−7 M) exhibited a significant increase in ETS-1 expression that was prevented by the angiotensin type 1 receptor blocker candesartan. NADPH oxidase inhibition with dyphenilene iodinium or apocynin also prevented ETS-1 induction, establishing the role of ROS as mediators of ETS-1 expression in response to ANG II. COX-2 inhibition prevented ETS-1 expression in response to ANG II, suggesting that COX-2 is required for ETS-1 induction. By utilizing short interfering RNAs against ETS-1, we have also determined that ETS-1 is required to induce the production of fibronectin in response to ANG II. Furthermore, rats infused with ANG II manifested increased glomerular expression of ETS-1. These studies unveil novel pathways that may play an important role in the pathogenesis of renal injury when RAS is activated.

scholarly journals Chinese Medicine Huzhen Tongfeng Formula Effectively Attenuates Gouty Arthritis by Inhibiting Arachidonic Acid Metabolism and Inflammatory Mediators

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Jianping Deng ◽  
Zicong Wu ◽  
Chen Chen ◽  
Zhenling Zhao ◽  
Yifei Li ◽  
...  
Keyword(s):  
Arachidonic Acid ◽  
Chinese Medicine ◽  
Inflammatory Mediators ◽  
Gouty Arthritis ◽  
Drug Application ◽  
Network Pharmacology ◽  
Pathway Enrichment ◽  
Therapeutic Benefits

The Chinese herbal medicine, Huzhen Tongfeng Formula (HZTF), derived from traditional Chinese medicine (TCM) practice, has recognized therapeutic benefits for gouty arthritis (GA). HZTF is currently in the late stage of approval process as a new anti-GA drug application. However, the underlying mechanism of HZTF as an antigout medication is unclear. In this study, we combined network pharmacology and experimental validation approaches to elucidate the mechanism of action of HZTF. First, the relative drug-disease target networks were constructed and analyzed for pathway enrichment. Potential pathways were then validated by in vitro and in vivo experiments. We found that 34 compounds from HZTF matched 181 potential drug targets. Topology analysis revealed 77 core targets of HZTF, which were highly related to gout, following screening of KEGG pathway enrichment. Further analysis demonstrated that the arachidonic acid metabolic pathway was the most relevant pathway involved in the mechanism of HZTF. Validation experiments showed that HZTF significantly inhibited the inflammatory cell infiltration into gouty joints, improved the swelling of affected joints, and increased the pain threshold. HZTF significantly reduced the transcription and production of various cytokines and inflammatory mediators in vitro. In particular, cyclooxygenase (COX)-1, COX-2, and 5-lipoxygenase were simultaneously downregulated. In conclusion, our study suggests that the antigout mechanism of HZTF is associated with the inhibition of the arachidonic acid pathway, resulting in the suppression of inflammatory cytokines and mediators. These findings extend our understanding of the pharmacological action of HZTF, rationalizing the application HZTF as an effective herbal therapy for GA.

Differential regulation of angiotensin II and losartan binding sites in glomeruli and mesangial cells

1994 ◽  
Vol 266 (3) ◽  
pp. F384-F393 ◽  
Author(s):  
D. Chansel ◽  
T. Bizet ◽  
S. Vandermeersch ◽  
P. Pham ◽  
B. Levy ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Binding Sites ◽  
Mesangial Cells ◽  
Present Report ◽  
Mrna Levels ◽  
Ang Ii ◽  
Experimental Conditions ◽  
Human Mesangial Cells

The aim of the present report was to examine the effect of several agents on angiotensin II (ANG II) and losartan receptors using 125I-[Sar1,Ala8]ANG II and [3H]losartan as radiolabeled ligand, respectively. ANG II receptors were downregulated in glomeruli from rats infused with ANG II during 3 wk or rats receiving losartan orally during 1 wk. The number of sites (Bmax) was reduced, but the dissociation constant (Kd) value was unchanged. Losartan receptors were downregulated in glomeruli from rats receiving losartan, but remained unchanged in glomeruli from rats infused with ANG II. Since in vivo administration of losartan results in increase of plasma ANG II and formation of metabolites, in vitro studies using human mesangial cells were performed to better analyze the present findings. Treatment of mesangial cells during 4 days by ANG II, losartan, or its metabolite, EXP-3174, also produced downregulation of 125I-[Sar1,Ala8]ANG II binding sites with a decreased Bmax and unchanged Kd value. Only treatment of mesangial cells by ANG II or EXP-3174 produced downregulation of [3H]losartan binding sites. In contrast, exposure of these cells to losartan resulted in upregulation of [3H]losartan binding sites. Under all conditions, only Bmax was modified. Whereas internalization of [3H]losartan in mesangial cells was negligible under all experimental conditions, there was an increase of the percentage of internalized 125I-[Sar1,Ala8]ANG II after exposure of the cells to ANG II or AT1 antagonists. No change was observed in mesangial cell AT1 receptor mRNA levels. This study demonstrates that 1) AT1 mRNA is expressed in human mesangial cells; 2) the characteristics of 125I-[Sar1,Ala8]ANG II and [3H]losartan binding sites in rat glomeruli and human mesangial cells are different, with Kd and Bmax values greater in both preparations when [3H]losartan was utilized; 3) both types of binding sites obey different regulations, and the effects of losartan in vivo are due in part to the associated increase in plasma ANG II levels and the transformation of the drug into its metabolite, EXP-3174; 4) downregulation of AT1 receptors does not depend on changes in mRNA expression but is associated with increased relative internalization.

scholarly journals Effect of High Extracellular Phosphate Concentration on Arachidonic Acid Production by Parathyroid TissueIn Vitro

2000 ◽  
Vol 11 (9) ◽  
pp. 1712-1718 ◽  
Author(s):  
YOLANDA ALMADÉN ◽  
ANTONIO CANALEJO ◽  
EVARISTO BALLESTEROS ◽  
GRACIA AÑÓN ◽  
MARIANO RODRÍGUEZ
Keyword(s):  
Arachidonic Acid ◽  
Angiotensin Ii ◽  
Intracellular Signaling ◽  
Parathyroid Tissue ◽  
Phosphate Concentration ◽  
High Calcium ◽  
Glomerulosa Cells ◽  
High Phosphate

Abstract.Recentin vivoandin vitrostudies show that high phosphate directly stimulates parathyroid hormone (PTH) secretion. However, little is known about the intracellular signaling system involved in the regulation of PTH secretion by extracellular phosphate. High extracellular calcium is coupled to the activation of phospholipase A2(PLA2) and the formation of arachidonic acid (AA), a potent inhibitor of PTH release. The present study was designed to evaluate whether a high phosphate concentration has an effect on the PLA2-AA pathway in parathyroid cells.In vitroexperiments were performed in parathyroid tissue obtained from normal rats and dogs. AA production was measured in parathyroid tissue in response to 1- and 4-mM phosphate concentration and after addition of PLA2to the medium. To determine whether the effect of phosphate on AA production in parathyroid cells was tissue specific, separate experiments were performed to test the effect of phosphate in rat adrenal glomerulosa cells, which are known to increase AA production in response to angiotensin II. The effect of sulfate, an ion with chemical characteristics similar to phosphate, on PTH secretion was also evaluated. In parathyroid tissue, a high phosphate concentration decreased the high calcium-induced AA production. This effect of phosphate was associated with an increase in PTH secretion. The addition of AA reversed the stimulatory effect of phosphate on PTH secretion. In another type of AA-responsive tissue, the adrenal glomerulosa, a high phosphate concentration did not affect the production of AA when stimulated by angiotensin II. In a normal phosphate concentration, the addition of PLA2stimulated AA production and decreased the PTH secretion. However, in a 4-mM phosphate concentration, the addition of PLA2did not reduce PTH secretion and did not stimulate AA production. Finally, sulfate did not affect PTH secretion. In conclusion, a high phosphate concentration affects the production of AA by parathyroid tissue. This effect of phosphate may be the mechanism by which a high phosphate concentration stimulates PTH secretion.

scholarly journals A new mechanism for the sex differences in angiotensin II-induced hypertension: the role of macula densa NOS1β-mediated tubuloglomerular feedback

2020 ◽  
Vol 319 (5) ◽  
pp. F908-F919
Author(s):  
Jie Zhang ◽  
Larry Qu ◽  
Jin Wei ◽  
Shan Jiang ◽  
Lan Xu ◽  
...  
Keyword(s):  
Sex Differences ◽  
Angiotensin Ii ◽  
Knockout Mice ◽  
Macula Densa ◽  
Tubuloglomerular Feedback ◽  
Ang Ii ◽  
Wild Type ◽  
Induced Hypertension

Females are protected against the development of angiotensin II (ANG II)-induced hypertension compared with males, but the mechanisms have not been completely elucidated. In the present study, we hypothesized that the effect of ANG II on the macula densa nitric oxide (NO) synthase 1β (NOS1β)-mediated tubuloglomerular feedback (TGF) mechanism is different between males and females, thereby contributing to the sexual dimorphism of ANG II-induced hypertension. We used microperfusion, micropuncture, clearance of FITC-inulin, and radio telemetry to examine the sex differences in the changes of macula densa NOS1β expression and activity, TGF response, natriuresis, and blood pressure (BP) after a 2-wk ANG II infusion in wild-type and macula densa-specific NOS1 knockout mice. In wild-type mice, ANG II induced higher expression of macula densa NOS1β, greater NO generation by the macula densa, and a lower TGF response in vitro and in vivo in females than in males; the increases of glomerular filtration rate, urine flow rate, and Na+ excretion in response to an acute volume expansion were significantly greater and the BP responses to ANG II were significantly less in females than in males. In contrast, these sex differences in the effects of ANG II on TGF, natriuretic response, and BP were largely diminished in knockout mice. In addition, tissue culture of human kidney biopsies (renal cortex) with ANG II resulted in a greater increase in NOS1β expression in females than in males. In conclusion, macula densa NOS1β-mediated TGF is a novel and important mechanism for the sex differences in ANG II-induced hypertension.

Angiotensin AT1 receptor-associated protein Arap1 in the kidney vasculature is suppressed by angiotensin II

2012 ◽  
Vol 302 (10) ◽  
pp. F1313-F1324 ◽  
Author(s):  
Elisabeth Doblinger ◽  
Klaus Höcherl ◽  
Katharina Mederle ◽  
Veronika Kattler ◽  
Steen Walter ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Mesangial Cells ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Glomerular Mesangial Cells ◽  
Water Restriction ◽  
Renal Vasculature ◽  
Contralateral Kidney

Arap1 is a protein that interacts with angiotensin II type 1 (AT1) receptors and facilitates increased AT1 receptor surface expression in vitro. In the present study, we assessed the tissue localization and regulation of Arap1 in vivo. Arap1 was found in various mouse organs, with the highest expression in the heart, kidney, aorta, and adrenal gland. Renal Arap1 protein was restricted to the vasculature and to glomerular mesangial cells and was absent from tubular epithelia. A similar localization was found in human kidneys. To test the hypothesis that angiotensin II may control renal Arap1 expression, mice were subjected to various conditions to alter the activity of the renin-angiotensin system. A high-salt diet (4% NaCl, 7 days) upregulated Arap1 expression in mice by 47% compared with controls (0.6% NaCl, P = 0.03). Renal artery stenosis (7 days) or water restriction (48 h) suppressed Arap1 levels compared with controls (−64 and −62% in the clipped and contralateral kidney, respectively; and −50% after water restriction, P < 0.01). Angiotensin II infusion (2 μg·kg−1·min−1, 7 days) reduced Arap1 mRNA levels compared with vehicle by 29% ( P < 0.01), whereas AT1 antagonism (losartan, 30 mg·kg−1·day−1, 7 days) enhanced Arap1 mRNA expression by 52% ( P < 0.01); changes in mRNA were paralleled by Arap1 protein abundance. Experiments with hydralazine and epithelial nitric oxide synthase−/− mice further suggested that Arap1 expression changed in parallel with angiotensin II, rather than with blood pressure per se. Similar to in vivo, Arap1 mRNA and protein were suppressed by angiotensin II in a time- and dose-dependent manner in cultured mesangial cells. In summary, Arap1 is highly expressed in the renal vasculature, and its expression is suppressed by angiotensin II. Thus Arap1 may serve as a local modulator of vascular AT1 receptor function in vivo.

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