Abstract P090: The Contractile Effect of Angiotensin II Type 1 Receptor Autoantibodies on Human Placental Vessels

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Li Song ◽  
Ronghua Zheng ◽  
Suli Zhang ◽  
Kehua Bai ◽  
Lihong Yang ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Vascular Ring ◽  
Dependent Manner ◽  
Extracellular Loop ◽  
Maximal Contraction ◽  
Concentration Dependent Manner ◽  
Placental Perfusion ◽  
Contraction Amplitude ◽  
Placental Blood

Background: Decreased placental perfusion induced by abnormal placental vascular contraction is one of the pathological basis of preeclampsia. It has been reported that the sera titers of the autoantibody against the second extracellular loop of angiotensin II type 1 receptor (AT1-AA) were negatively correlated with placental blood flow in preeclampsia. Our previous study has found that AT1-AA could induce contraction of rat thoracic aorta and coronary rings by activing angiotensin II type 1 receptor (AT1R). However, there is no direct evidence for explaining whether AT1-AA might cause vasoconstriction on human placental blood vessels. Methods: The SD rats were immunized with the synthetic peptide corresponding to the sequence of the second extracellular loop of the human AT1 receptor (AT1R-EC II ), and anti-AT1R antibody (AT1R-Ab) was extracted. The expression of AT1R on human placental vessels was determined by immunohistochemistry. The effects of AT1R-Ab on placental vessels were measured with isolated vascular ring technique. Results: (1) AT1R was highly expressed in the human placental artery, vein and vascular endothelial cells. (2) AT1R-Ab (10 mmol/L) respectively enhanced the contraction of the placental arteries and veins (29.21% ± 3.7% vs . 21.35% ± 2.8%, P >0.05), which could be completely reversed when AT1R was blocked by AT1R inhibitor. (3) AT1R-Ab (0.1, 1 and 10 mmol/L) induced placental vasoconstriction of normal human. The percentage of maximal contraction was 2.73% ± 1.11%, 4.00% ± 3.2% and 33.30% ± 5.6%, respectively. There was significantly difference between the three groups for contraction amplitude induced by different concentrations of AT1R-Ab ( P <0.01). (4) AT1R-Ab (0.1, 1 and 10 mmol/L) induced placental vasoconstriction of preeclampsia. The percentage of maximal contraction was 1.74% ± 0.3%, 5.58% ± 1.41% and 3.73% ± 2.5%, respectively. There was significantly difference between the three groups for contraction amplitude induced by different concentrations of AT1R-Ab ( P <0.01). Conclusion: AT1R-Ab could induce human placental vasoconstriction in a concentration-dependent manner, which suggested that AT1-AA might be involved in the pathogenesis of preeclampsia by directly contracted placental blood vessles.

scholarly journals Preparation and Biological Activity of the Monoclonal Antibody against the Second Extracellular Loop of the Angiotensin II Type 1 Receptor

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Mingming Wei ◽  
Chengrui Zhao ◽  
Suli Zhang ◽  
Li Wang ◽  
Huirong Liu ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Biological Activity ◽  
Angiotensin Ii ◽  
Abdominal Cavity ◽  
Beat Frequency ◽  
Neonatal Rat ◽  
Logarithmic Phase ◽  
Extracellular Loop ◽  
Mouse Ascites

The current study was to prepare a mouse-derived antibody against the angiotensin II type 1 receptor (AT1-mAb) based on monoclonal antibody technology, to provide a foundation for research on AT1-AA-positive diseases. Balb/C mice were actively immunized with the second extracellular loop of the angiotensin II type 1 receptor (AT1R-ECII). Then, mouse spleen lymphocytes were fused with myeloma cells and monoclonal hybridomas that secreted AT1-mAb were generated and cultured, after which those in logarithmic-phase were injected into the abdominal cavity of mice to retrieve the ascites. Highly purified AT1-mAb was isolated from mouse ascites after injection with 1 × 107hybridomas. A greater amount of AT1-mAb was purified from mouse ascites compared to the cell supernatant of hybridomas. AT1-mAb purified from mouse ascites constricted the thoracic aorta of mice and increased the beat frequency of neonatal rat myocardial cells via the AT1R, identical to the effects of AT1-AA extracted from patients’ sera. Murine blood pressure increased after intravenous injection of AT1-mAb via the tail vein. High purity and good biological activity of AT1-mAb can be obtained from mouse ascites after intraperitoneal injection of monoclonal hybridomas that secrete AT1-mAb. These data provide a simple tool for studying AT1-AA-positive diseases.

scholarly journals Interactions of Dichlorodiphenyltrichloroethane (DDT) and Dichlorodiphenyldichloroethylene (DDE) With Skeletal Muscle Ryanodine Receptor Type 1

2019 ◽  
Vol 170 (2) ◽  
pp. 509-524
Author(s):  
Kim M Truong ◽  
Gennady Cherednichenko ◽  
Isaac N Pessah
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Membrane Vesicles ◽  
Receptor Type ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Voltage Gated Sodium Channels ◽  
Muscle Health ◽  
Living Organisms

Abstract Dichlorodiphenyltrichloroethane (DDT) and its metabolite dichlorodiphenyldichloroethylene (DDE) are ubiquitous in the environment and detected in tissues of living organisms. Although DDT owes its insecticidal activity to impeding closure of voltage-gated sodium channels, it mediates toxicity in mammals by acting as an endocrine disruptor (ED). Numerous studies demonstrate DDT/DDE to be EDs, but studies examining muscle-specific effects mediated by nonhormonal receptors in mammals are lacking. Therefore, we investigated whether o,p′-DDT, p,p′-DDT, o,p′-DDE, and p,p′-DDE (DDx, collectively) alter the function of ryanodine receptor type 1 (RyR1), a protein critical for skeletal muscle excitation-contraction coupling and muscle health. DDx (0.01–10 µM) elicited concentration-dependent increases in [3H]ryanodine ([3H]Ry) binding to RyR1 with o,p′-DDE showing highest potency and efficacy. DDx also showed sex differences in [3H]Ry-binding efficacy toward RyR1, where [3H]Ry-binding in female muscle preparations was greater than male counterparts. Measurements of Ca2+ transport across sarcoplasmic reticulum (SR) membrane vesicles further confirmed DDx can selectively engage with RyR1 to cause Ca2+ efflux from SR stores. DDx also disrupts RyR1-signaling in HEK293T cells stably expressing RyR1 (HEK-RyR1). Pretreatment with DDx (0.1–10 µM) for 100 s, 12 h, or 24 h significantly sensitized Ca2+-efflux triggered by RyR agonist caffeine in a concentration-dependent manner. o,p′-DDE (24 h; 1 µM) significantly increased Ca2+-transient amplitude from electrically stimulated mouse myotubes compared with control and displayed abnormal fatigability. In conclusion, our study demonstrates DDx can directly interact and modulate RyR1 conformation, thereby altering SR Ca2+-dynamics and sensitize RyR1-expressing cells to RyR1 activators, which may ultimately contribute to long-term impairments in muscle health.

scholarly journals Renal microvascular actions of calcitonin gene-related peptide

1998 ◽  
Vol 274 (6) ◽  
pp. F1078-F1085 ◽  
Author(s):  
Martina Reslerova ◽  
Rodger Loutzenhiser
Keyword(s):  
Angiotensin Ii ◽  
Rat Kidney ◽  
Elevated Pressure ◽  
Calcitonin Gene Related Peptide ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Renal Vasoconstriction ◽  
Related Peptide ◽  
Calcitonin Gene

Calcitonin gene-related peptide (CGRP) is a potent vasodilator that is suggested to act via ATP-sensitive K channels (KATP). In the present study, we examined the actions of CGRP on pressure- and angiotensin II-induced vasoconstriction, using the in vitro perfused hydronephrotic rat kidney. Elevated pressure (from 80 to 180 mmHg) and 0.1 nM angiotensin II elicited similar decreases in afferent diameter in this model. CGRP inhibited myogenic reactivity in a concentration-dependent manner, completely preventing pressure-induced constriction at 10 nM (95 ± 10% inhibition). These effects were partially attenuated by 10 μM glibenclamide (62 ± 16% inhibition, P = 0.025), indicating both KATP-dependent and -independent actions of CGRP. In contrast, 10 nM CGRP inhibited angiotensin II-induced vasoconstriction by only 54 ± 11%, and this action was not affected by glibenclamide (41 ± 11%, P = 0.31). CGRP also inhibited the efferent arteriolar response to angiotensin II in the absence and presence of glibenclamide. Pinacidil (1.0 μM), a KATP opener also preferentially inhibited pressure- vs. angiotensin II-induced vasoconstriction (97 ± 5 and 59 ± 13% inhibition, respectively; P = 0.034). We conclude that the renal vasodilatory mechanisms of CGRP are pleiotropic and involve both KATP-dependent and -independent pathways. The effectiveness of CGRP in opposing renal vasoconstriction and the role of KATP in this action appear to depend on the nature the underlying vasoconstriction. We suggest that this phenomenon reflects an inhibition of KATP activation by angiotensin II.

Potentiation of angiotensin II-stimulated vascular contraction by lithium

1995 ◽  
Vol 268 (5) ◽  
pp. H2009-H2016
Author(s):  
M. E. Ullian ◽  
L. G. Walsh ◽  
K. C. Wong ◽  
C. J. Allan
Keyword(s):  
Angiotensin Ii ◽  
Inositol Phosphate ◽  
Cytosolic Calcium ◽  
Rat Aorta ◽  
Dependent Manner ◽  
Ang Ii ◽  
Concentration Dependent Manner ◽  
Adrenergic Agents ◽  
Phosphoinositide Signaling ◽  
Protein Kinase C Inhibitor

Previous studies have suggested that lithium prolongs or enhances vascular contractions stimulated by alpha-adrenergic agents. The present study was performed to determine whether a similar phenomenon occurs with angiotensin II (ANG II)-stimulated contractions and whether this phenomenon results from interactions with the phosphoinositide signaling system. Contractions of rat aortic rings with 100 nM ANG II were 38% greater in the presence of 20 mM LiCl than in its absence (0.47 +/- 0.07 vs. 0.34 +/- 0.05 g tension/mg dry tissue wt, P < 0.01). The effects of lithium on inositol phosphate responses, diacylglycerol responses, and intracellular calcium concentration on single or repeated stimulations with ANG II were then examined in vascular smooth muscle cells cultured from rat aorta. Cells exposed twice to 100 nM ANG II contained 50% lower inositol trisphosphate levels (InsP3) and 10% lower diacylglycerol levels than cells exposed to ANG II only once. LiCl or lithium acetate abolished these desensitizations in a concentration-dependent manner. Similarly, InsP3 and diacylglycerol responses to a single exposure of ANG II were heightened by lithium (by 75 and 25%, respectively), and the duration of the responses was prolonged by lithium (5- and 2-fold, respectively). In contrast, ANG II-stimulated calcium transients were not enhanced or prolonged by lithium, nor was desensitization of ANG II-stimulated cytosolic calcium mobilization upon serial exposures abolished by lithium. When ring contraction studies were repeated in the presence of the protein kinase C inhibitor staurosporine (150 nM), lithium no longer potentiated ANG II contractions [0.38 +/- 0.03 (control) vs. 0.35 +/- 0.06 g tension/mg dry tissue wt (lithium)].(ABSTRACT TRUNCATED AT 250 WORDS)

Intrinsic ANG II type 1 receptor stimulation contributes to recovery of postischemic mechanical function

1998 ◽  
Vol 274 (5) ◽  
pp. H1524-H1531 ◽  
Author(s):  
William R. Ford ◽  
Alexander S. Clanachan ◽  
Gary D. Lopaschuk ◽  
Richard Schulz ◽  
Bodh I. Jugdutt
Keyword(s):  
Recovery Of Function ◽  
Left Ventricular ◽  
Dependent Manner ◽  
Mechanical Function ◽  
Ang Ii ◽  
Concentration Dependent Manner ◽  
Proton Production ◽  
Rat Hearts ◽  
Postischemic Recovery

To determine whether intrinsic angiotensin II (ANG II) type 1 receptor (AT1-R) stimulation modulates recovery of postischemic mechanical function, we studied the effects of selective AT1-R blockade with losartan on proton production from glucose metabolism and recovery of function in isolated working rat hearts perfused with Krebs-Henseleit buffer containing palmitate, glucose, and insulin. Aerobic perfusion (50 min) was followed by global, no-flow ischemia (30 min) and reperfusion (30 min) in the presence ( n = 10) or absence ( n = 14) of losartan (1 μmol/l) or the cardioprotective adenosine A1receptor agonist N 6-cyclohexyladenosine (CHA, 0.5 μmol/l, n = 11). During reperfusion in untreated hearts (controls), left ventricular (LV) minute work partially recovered to 38% of aerobic baseline, whereas proton production increased to 155%. Compared with controls, CHA improved recovery of LV work to 79% and reduced proton production to 44%. Losartan depressed recovery of LV work to 0% without altering proton production. However, exogenous ANG II (1–100 nmol/l) in combination with losartan restored recovery of LV work during reperfusion in a concentration-dependent manner, suggesting that postischemic recovery of function depends on intrinsic AT1-R stimulation.

Angiotensin II activates two distinct cation conductances in a concentration dependent manner which display TRPC like properties

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Sohag Nafis Saleh ◽  
Anthony P Albert ◽  
Claire M Peppiatt‐ Wildman ◽  
William A Large
Keyword(s):  
Angiotensin Ii ◽  
Dependent Manner ◽  
Concentration Dependent Manner

scholarly journals Factors regulating the production of prostaglandin E2 and prostacyclin (prostaglandin I2) in rat and human adipocytes

1987 ◽  
Vol 247 (2) ◽  
pp. 389-394 ◽  
Author(s):  
B Richelsen
Keyword(s):  
Angiotensin Ii ◽  
Cyclic Amp ◽  
Prostaglandin E2 ◽  
Acetylsalicylic Acid ◽  
Dependent Manner ◽  
Human Adipocytes ◽  
Prostaglandin I2 ◽  
Concentration Dependent Manner ◽  
Rat Adipocytes ◽  
Isolated Adipocytes

The regulation of PGE2 (prostaglandin E2) and PGI2 (prostaglandin I2; prostacyclin) formation was investigated in isolated adipocytes. The formation of both PGs was stimulated by various lipolytic agents such as isoproterenol, adrenaline and dibutyryl cyclic AMP. During maximal stimulation the production of PGE2 and PGI2 (measured as 6-oxo-PGF1 alpha) was 0.51 +/- 0.04 and 1.21 +/- 0.09 ng/2 h per 10(6) cells respectively. Thus PGI2 was produced in excess of PGE2 in rat adipocytes. The production of the PGs was inhibited by indomethacin and acetylsalicylic acid in a concentration-dependent manner. The half-maximal effective concentration of indomethacin was 328 +/- 38 nM and that of acetylsalicylic acid was 38.5 +/- 5.3 microM. The PGs were maximally inhibited by 70-75% after incubation for 2 h. In contrast with their effect on PG production, the two agents had a small potentiating effect on the stimulated lipolysis (P less than 0.05). The phospholipase inhibitors mepacrine and chloroquine inhibited both PG production and triacylglycerol lipolysis and were therefore unable to indicate whether the PG precursor, arachidonic acid, originates from phospholipids or triacylglycerols in adipocytes. Angiotensin II significantly (P less than 0.05) stimulated both PGE2 and PGI2 production in rat adipocytes without affecting triacylglycerol lipolysis. Finally, it was shown that PGE2 and PGI2 were also produced in human adipocytes, although in smaller quantities than in rat adipocytes. It is concluded that the production of PGs in isolated adipocytes is regulated by various hormones. Moreover, at least two separate mechanisms for PG production may exist in adipocytes: (1) a mechanism that is activated concomitantly with triacylglycerol lipolysis (and cyclic AMP) and (2) an angiotensin II-sensitive, but lipolysis (and cyclic AMP)-independent mechanism.

scholarly journals Angiotensin II Suppresses Rev-erbα Expression in THP-1 Macrophages via the Ang II Type 1 Receptor/Liver X Receptor α Pathway

2018 ◽  
Vol 46 (1) ◽  
pp. 303-313 ◽  
Author(s):  
Shipeng Wang ◽  
Xia Gu ◽  
Qi Zhang ◽  
Xiling Zhang ◽  
Yilan Li ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Protein Expression ◽  
Atherosclerotic Lesion ◽  
Liver X Receptor ◽  
Time Dependent ◽  
Dependent Manner ◽  
Ang Ii ◽  
Raw264.7 Macrophages ◽  
Liver X Receptor Α

Background/Aims: Angiotensin II (Ang II) regulates the expression of some core clock genes; excess Ang II leads to atherosclerosis advancement. Macrophage Rev-erbα mediates clockwork and inflammation, and plays a role in atherosclerotic lesion progression. However, the role of Ang II in regulating Rev-erbα expression in macrophages remains unclarified. Methods: We induced THP-1 macrophages by phorbol 12-myristate 13-acetate and investigated the effect of Ang II on Rev-erbα expression via real-time polymerase chain reaction, western blotting and small interfering RNA (siRNA) techniques. The cytotoxicity of the Rev-erbα agonist SR9009 was analyzed using a (3-[4,5-dimethylthiazol-2-yl])-2,5- diphenyltetrazolium bromide assay. Results: Ang II suppressed Rev-erbα mRNA and protein expression in THP-1 macrophages in a dose and time dependent manner. This effect was mediated via Ang II type 1 receptor (AT1R), and not Ang II type 2 receptor or peroxisome proliferator-activated receptor γ (PPARγ). Consistent with Rev-erbα expression regulated by Ang II, the liver X receptor α (LXRα) protein expression was downregulated in a time-dependent manner after Ang II treatment. The activation or silence of LXRα significantly increased or decreased Rev-erbα expression regulated by Ang II, respectively. This suggests that LXRα is involved in the effect of Ang II on Rev-erbα expression. MMP-9 mRNA expressions were significantly suppressed by SR9009 in THP-1 and RAW264.7 macrophages; moreover, SR9009-treatment significantly reduced Ang II–induced MMP-9 protein expressions in two types of macrophages. Conclusion: Ang II downregulates Rev-erbα expression in THP-1 macrophages via the AT1R/LXRα pathway.

scholarly journals Angiotensin II-Induced Mitogen-Activated Protein Kinase Phosphatase-1 Expression in Bovine Adrenal Glomerulosa Cells: Implications in Mineralocorticoid Biosynthesis

Endocrinology ◽  
2007 ◽  
Vol 148 (11) ◽  
pp. 5573-5581 ◽  
Author(s):  
Andrés J. Casal ◽  
Stéphane Ryser ◽  
Alessandro M. Capponi ◽  
Carine F. Wang-Buholzer
Keyword(s):  
Angiotensin Ii ◽  
Mapk Pathway ◽  
Fold Increase ◽  
Zona Glomerulosa ◽  
Mitogen Activated Protein Kinase ◽  
Receptor Subtype ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aldosterone Production ◽  
Glomerulosa Cells

Angiotensin II (AngII) stimulates aldosterone biosynthesis in the zona glomerulosa of the adrenal cortex. AngII also triggers the MAPK pathways (ERK1/2 and p38). Because ERK1/2 phosphorylation is a transient process, phosphatases could play a crucial role in the acute steroidogenic response. Here we show that the dual specificity (threonine/tyrosine) MAPK phosphatase-1 (MKP-1) is present in bovine adrenal glomerulosa cells in primary culture and that AngII markedly increases its expression in a time- and concentration-dependent manner (IC50 = 1 nm), a maximum of 548 ± 10% of controls being reached with 10 nm AngII after 3 h (n = 3, P &lt; 0.01). This effect is completely abolished by losartan, a blocker of the AT1 receptor subtype. Moreover, this AngII-induced MKP-1 expression is reduced to 250 ± 35% of controls (n = 3, P &lt; 0.01) in the presence of U0126, an inhibitor of ERK1/2 phosphorylation, suggesting an involvement of the ERK1/2 MAPK pathway in MKP-1 induction. Indeed, shortly after AngII-induced phosphorylation of ERK1/2 (220% of controls at 30 min), MKP-1 protein expression starts to increase. This increase is associated with a reduction in ERK1/2 phosphorylation, which returns to control values after 3 h of AngII challenge. Enhanced MKP-1 expression is essentially due to a stabilization of MKP-1 mRNA. AngII treatment leads to a 53-fold increase in phosphorylated MKP-1 levels and a doubling of MKP-1 phosphatase activity. Overexpression of MKP-1 results in decreased phosphorylation of ERK1/2 and aldosterone production in response to AngII stimulation. These results strongly suggest that MKP-1 is the specific phosphatase induced by AngII and involved in the negative feedback mechanism ensuring adequate ERK1/2-mediated aldosterone production in response to the hormone.

scholarly journals Angiotensin II type 1 receptor blocker attenuates the activation of ERK and NADPH oxidase by mechanical strain in mesangial cells in the absence of angiotensin II

2009 ◽  
Vol 296 (5) ◽  
pp. F1052-F1060 ◽  
Author(s):  
Junichi Yatabe ◽  
Hironobu Sanada ◽  
Midori Sasaki Yatabe ◽  
Shigeatsu Hashimoto ◽  
Minoru Yoneda ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Angiotensin Ii ◽  
Nadph Oxidase ◽  
Mesangial Cells ◽  
Mechanical Strain ◽  
Dependent Manner ◽  
Ang Ii ◽  
Erk Phosphorylation ◽  
Extracellular Signal

It has been reported that mechanical strain activates extracellular signal-regulated protein kinases (ERK) without the involvement of angiotensin II (Ang II) in cardiomyocytes. We examined the effects of mechanical strain on ERK phosphorylation levels in the absence of Ang II using rat mesangial cells. The ratio of phosphorylated ERK (p-ERK) to total ERK expression was increased by cyclic mechanical strain in a time- and elongation strength-dependent manner. With olmesartan [Ang II type 1 receptor (AT1R) antagonist] pretreatment, p-ERK plateau levels decreased in a dose-dependent manner (EC50 = 1.3 × 10−8 M, maximal inhibition 50.6 ± 11.0% at 10−5 M); a similar effect was observed with RNA interference against Ang II type 1A receptor (AT1AR) and Tempol, a superoxide dismutase mimetic. In addition to the inhibition of p-ERK levels, olmesartan blocked the increase in cell surface and phosphorylated p47phox induced by mechanical strain and also lowered the mRNA expression levels of NADPH oxidase subunits. These results demonstrate that mechanical strain stimulates AT1R to phosphorylate ERK in mesangial cells in the absence of Ang II. This mechanotransduction mechanism is involved in the oxidative stress caused by NADPH oxidase and is blocked by olmesartan. The inverse agonistic activity of this AT1R blocker may be useful for the prevention of mesangial proliferation and renal damage caused by mechanical strain/oxidative stress regardless of circulating or tissue Ang II levels.

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