Angiotensin II Group Research Articles

A Pilot Study of Renin-Guided Angiotensin-II Infusion to Reduce Kidney Stress After Cardiac Surgery.

Vasoplegia is common after cardiac surgery, is associated with hyperreninemia, and can lead to acute kidney stress. We aimed to conduct a pilot study to test the hypothesis that, in vasoplegic cardiac surgery patients, angiotensin-II (AT-II) may not increase kidney stress (measured by [TIMP-2]*[IGFBP7]). We randomly assigned patients with vasoplegia (cardiac index [CI] > 2.1l/min, postoperative hypotension requiring vasopressors) and Δ-renin (4-hour postoperative-preoperative value) ≥3.7 µU/mL, to AT-II or placebo targeting a mean arterial pressure ≥65 mm Hg for 12 hours. The primary end point was the incidence of kidney stress defined as the difference between baseline and 12 hours [TIMP-2]*[IGFBP7] levels. Secondary end points included serious adverse events (SAEs). We randomized 64 patients. With 1 being excluded, 31 patients received AT-II, and 32 received placebo. No significant difference was observed between AT-II and placebo groups for kidney stress (Δ-[TIMP-2]*[IGFBP7] 0.06 [ng/mL] 2 /1000 [Q1-Q3, -0.24 to 0.28] vs -0.08 [ng/mL] 2 /1000 [Q1-Q3, -0.35 to 0.14]; P = .19; Hodges-Lehmann estimation of the location shift of 0.12 [ng/mL] 2 /1000 [95% confidence interval, CI, -0.1 to 0.36]). AT-II patients received less fluid during treatment than placebo patients (2946 vs 3341 mL, P = .03), and required lower doses of norepinephrine equivalent (0.19 mg vs 4.18mg, P < .001). SAEs were reported in 38.7% of patients in the AT-II group and in 46.9% of patients in the placebo group. The infusion of AT-II for 12 hours appears feasible and did not lead to an increase in kidney stress in a high-risk cohort of cardiac surgery patients. These findings support the cautious continued investigation of AT-II as a vasopressor in hyperreninemic cardiac surgery patients.

Paeonol improves angiotensin II-induced cardiac hypertrophy by suppressing ferroptosis

The aim of this study was to investigate the protective effect of paeonol (pae) on an angiotensin II (AngII)-induced cardiac hypertrophy mouse model. First, AngII mouse models were constructed and randomly grouped into the control (con), AngII, and AngII + Pae groups. Compared with that in the blank group, the surface area of myocardial cells in the AngII group increased significantly. In contrast to that in the AngII group, the cardiomyocyte surface area in the Pae group was significantly reduced. Ultrasound results showed that the myocardial function of mice in the AngII group was decreased compared with that in the Con group, while the myocardial function of mice in the Pae treatment was significantly improved. Moreover, the Fe2+ and lipid peroxide levels of primary cardiomyocytes were significantly increased after treatment with AngII and were significantly decreased after the addition of Pae. Compared with those in the Con group, cristae were reduced and the outer membrane was lost in the myocardial tissues of the AngII group, and myocardial MDA, ROS, and Fe2+ levels were increased. However, myocardial damage was significantly alleviated after Pae treatment, and myocardial MDA, ROS, and Fe2+ levels were reduced. Moreover, in myocardial tissue, AngII reduced the protein levels of xCT and GPX4, while the levels of both xCT and GPX4 were increased after Pae treatment. In conclusion, Pae protected the hearts of AngII mice by upregulating the protein expression of xCT and GPX4 and resisting AngII-induced ferroptosis in cardiomyocytes.

Asiaticoside promotes heart autonomic nerve repair through receptor activator of nuclear factor kappa-B ligand pathway in coronary heart disease

This experiment intends to observe the effects of Asiaticoside on angiotensin II (AngII)-induced coronary heart disease (CHD) by regulating nuclear factor κ-B ligand receptor activator and RANK pathway (RANKL/RANK). Cardiomyocytes of rats with CHD were divided into AngII group (2 μmol/L), blank control group, and asiaticoside group (2 μmol/L and 10 μmol/L). After 24 hours of intervention, proliferation and apoptosis was assessed. At the same time, the expressions of RANKL, RANK and α-smooth muscle actin (α-SMA) were measured. Compared with blank group, the proliferation ability of cardiomyocytes with CHD in AngII group was significantly decreased and it increased after asiaticoside treatment (P &lt;0.05). The apoptosis of cardiomyocytes in AngII group was higher than blank group and asiaticoside group. Cardiomyocytes proliferation in asiaticoside group was the most obvious (P &lt;0.05). α-SMA expression decreased in AngII group and increased after asiaticoside treatment (P &lt;0.05). RANKL and RANK mRNA in CHD were significantly upregulated after administration of asiaticoside (P &lt;0.05). RANKL/RANK expression was high in normal CHD cardiomyocytes and reduced after Ang II stimulation. Asiaticoside promotes cardiomyocyte proliferation in CHD by promoting RANKL/RANK signaling, thereby reducing the possibility of heart failure in CHD.

ROLE OF METALLOPROTEINASES AND ROS GENERATION IN THE AORTA OF ELASTASE-2 KNOCKOUT MICE IN ABDOMINAL AORTIC ANEURYSM MODEL

Objective: Elastase-2 (ELA-2) enzyme generates angiotensin-II (AngII) in arteries and is implicated in abnormal vascular remodeling in animal models. Our group demonstrated previously that ELA-2 knockout (ELA-2KO) mice were less susceptible to developing an aorta dilation in response to AngII infusion. This study hypothesizes that metalloproteinases and ROS generation in ELA-2KO mice mediate less susceptibility to aorta dilation and abdominal aortic aneurysm (AAA). Design and method: Male wild type (C57bl/6, WT) and ELA-2KO (CELA-2aTm1Bdr) mice were treated with either saline or AngII (2.28g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. Mice were divided into four groups: WT treated with saline (WT+SAL, n = 5), ELA-2KO treated with saline (ELA-2KO+SAL, n = 5), WT treated with AngII (WT+AngII,n = 5), and ELA-2KO treated with AngII (ELA-2KO+AngII, n = 5). The vascular ultrasound (US) was done before treatment and once a week during 28 days of treatment. The MMP- 2 and MMP-9 analyzes were done by zymography, ROS generation by DHE analyses, and alfa-actin expression by immunofluorescence in all aorta mice groups. ANOVA and Kruskal Wallis tests were used to compare the average between groups. This study is approved by CEUA (n.131/2019). Results: AngII treatment was associated with increased MMPs expression in the WT group aorta (WT+AngII vs. WT+SAL p&lt;0.05). The aorta ELA-2KO group showed no difference in MMPs in response to AngII infusion compared to ELA-2KO+SAL group (p = 0.81). The ROS generation had upregulated in aorta ELA-2KO+Ang II mice compared to ELA-2KO+SAL (p&lt;0.001) and aorta WT+AngII compared with WT+SAL (p&lt;0.0001). AngII treatment was associated with decreased ROS generation in the aorta ELA-2KO+AngII group compared with WT+AngII (p = 0.0051). The alfa-actin expression was similar in all groups. Our data demonstrate that AngII treatment did not increase the expression of MMPs in aorta ELA-2KO but was associated with an upregulation for ROS generation. Conclusions: Taken together, this suggests that ELA-2KO mice's resistance to developing an aorta dilation/AAA is related to MMPs and ROX generation. Our results also highlight the importance of the local/tissue response in the pathophysiology of AAA.

Novel preventive effect of isorhamnetin on electrical and structural remodeling in atrial fibrillation.

Isorhamnetin, a natural flavonoid, has strong antioxidant and antifibrotic effects, and a regulatory effect against Ca2+-handling. Atrial remodeling due to fibrosis and abnormal intracellular Ca2+ activities contributes to initiation and persistence of atrial fibrillation (AF). The present study investigated the effect of isorhamnetin on angiotensin II (AngII)-induced AF in mice. Wild-type male mice (C57BL/6J, 8 weeks old) were assigned to three groups: (1) control group, (2) AngII-treated group, and (3) AngII- and isorhamnetin-treated group. AngII (1000 ng/kg/min) and isorhamnetin (5 mg/kg) were administered continuously via an implantable osmotic pump for two weeks and intraperitoneally one week before initiating AngII administration, respectively. AF induction and electrophysiological studies, Ca2+ imaging with isolated atrial myocytes and HL-1 cells, and action potential duration (APD) measurements using atrial tissue and HL-1 cells were performed. AF-related molecule expression was assessed and histopathological examination was performed. Isorhamnetin decreased AF inducibility compared with the AngII group and restored AngII-induced atrial effective refractory period prolongation. Isorhamnetin eliminated abnormal diastolic intracellular Ca2+ activities induced by AngII. Isorhamnetin also abrogated AngII-induced APD prolongation and abnormal Ca2+ loading in HL-1 cells. Furthermore, isorhamnetin strongly attenuated AngII-induced left atrial enlargement and atrial fibrosis. AngII-induced elevated expression of AF-associated molecules, such as ox-CaMKII, p-RyR2, p-JNK, p-ERK, and TRPC3/6, was improved by isorhamnetin treatment. The findings of the present study suggest that isorhamnetin prevents AngII-induced AF vulnerability and arrhythmogenic atrial remodeling, highlighting its therapeutic potential as an anti-arrhythmogenic pharmaceutical or dietary supplement.

Dihydro-artemisinin inhibits angiotensin II-induced cardiac fibroblasts proliferation and induces apoptosis through phosphoinositide 3-kinase/akt pathway

Cardiac fibroblasts (CFs) abnormal proliferation can trigger myocardial fibrosis, which is closely related to a variety of cardiovascular diseases. This study investigated the effect of dihydroartemisinin (DHA) on CF growth through PI3K/AKT with angiotensin II (AngII). CCK-8 method and EdU were used detect cell proliferation, and flow cytometry assessed apoptosis of CFs. The PI3K and AKT expressions were determined, whilst immunofluorescence staining and RT-qPCR measured α-smooth muscle actin (α-SMA) level. With rat CFs exhibiting typical fibroblast morphology and nuclei in spindle, oval or polygonal shape, these cells were positive for the fibroblast marker vimentin. Treatment with AngII resulted in increased proliferation of CFs, but the proliferation declined in the presence of DHA (p &lt; 0.05). Meanwhile, the AngII group had lower apoptosis of CFs than blank and DHA groups with highest apoptosis observed in the DHA group. α-SMA increased at the mRNA and protein levels after Ang II treatment and decreased after DHA treatment (p &lt; 0.05). Importantly, the Ang II upregulated PI3K and AKT in CFs (p &lt; 0.05) and the increase was abrogated by DHA administration with lowest levels (p &lt; 0.05). Ang II activates PI3K/Akt in normal CFs, as administration of DHA can inhibit the effect of Ang II, thereby inhibiting proliferation of CFs induced by AngII and inducing apoptosis.

Central Nucleus of Amygdala Mediate Pressor Response Elicited by Microinjection of Angiotensin II into the Parvocellular Paraventricular Nucleus in Rats.

Background: The Paraventricular Hypothalamic Nucleus (PVN) coordinates autonomic and neuroendocrine systems to maintain homeostasis. Microinjection of angiotensin II (AngII) into the PVN has been previously shown to produce pressor and bradycardia responses. Anatomical evidence has indicated that a substantial proportion of PVN neurons is connected with the neurons in the central amygdala (CeA). The present study aimed to examine the possible contribution of the CeA in cardiovascular responses evoked by microinjection of AngII into the parvocellular portion of PVN (PVNp) before and after microinjection of cobalt chloride (CoCl2) into the CeA.Methods: The experiments were conducted at the Department of Physiology of Shiraz University of Medical Sciences, from April 2019 to November 2019. There were two groups of 21 eight-week-old urethane anesthetized male rats, namely saline (n=9 rats) and AngII (n=12 rats) groups. Drugs (100 nL) were microinjected via a single-glass micropipette into the PVNp and CeA. Their blood pressure (BP) and heart rate (HR) were recorded throughout the experiments. The mean arterial pressure (MAP) and heart rate (HR) were compared to the pre-injection values using paired t test, and to those of the saline group using independent t test.Results: Microinjection of AngII into the PVNp produced pressor response (P<0.0001) with no significant changes in HR (P=0.70). Blockade of CeA with CoCl2 attenuated the pressor response to microinjection of AngII into the PVNp (P<0.001).Conclusion: In the PVNp, Ang II increased the rats’ blood pressure. This response was in part mediated by the CeA. Our study suggested that these two nuclei cooperate to perform their cardiovascular functions.

Angiotensin II infusion in COVID-19: An international, multicenter, registry-based study.

To expand our understanding of the role of angiotensin II (ANGII) in coronavirus infectious disease 2019 (COVID‐19), we conducted an international, multicenter registry study to assess the use of ANGII in patients with COVID‐19 compared to patients not receiving ANGII. Critically ill adult patients who were diagnosed with COVID‐19 and received ANGII were matched with COVID‐19 patients not receiving ANGII according to age, respiratory support, history of hypertension, use of angiotensin‐converting enzyme inhibitors and/or ANGII receptor blocker, and date of admission. All outcomes were exploratory in nature and included improvement in oxygenation, duration of organ support, and mortality. In one year, 132 patients were included (65 in the ANGII group and 67 in the control group), and patients were comparable in baseline characteristics. During the first 12 h of infusion, patients in the ANGII had a faster decrease in FiO2 and maintained similar mean arterial pressure levels. Hospital mortality was not statistically significantly different between the groups (53.8% vs. 40.3%; p = 0.226). Within the limitations of such a study design, our findings confirm previous observations of a potentially positive effect of ANGII on blood pressure and FiO2 but no effect on patient‐centered outcomes.

Effectiveness of Angiotensin II for Catecholamine Refractory Septic or Distributive Shock on Mortality: A Propensity Score Weighted Analysis of Real-World Experience in the Medical ICU.

This study examined ATII as a third-line vasopressor based on institutional approval. Retrospective observational cohort study. Medical ICU at an academic tertiary care medical center. Adult patients requiring 3 or more vasopressor agents for septic shock or other forms of distributed shock from September 1, 2018, to January 31, 2020. Effect of ATII after norepinephrine and vasopressin on mortality and mean arterial blood pressure response after 3 hours of administration. One-hundred forty-seven patients, 56 receiving ATII and 91 receiving another vasopressor (non-ATII), were enrolled. Patients in the ATII group had higher mortality compared to the non-ATII group, and more required 5 or greater vasopressor agents (p < 0.01). After propensity score weighting, there remains a trend in higher mortality in the ATII compared to non-ATII group, but not statistically significant (86.0% vs 71.0%, p = 0.16). More patients in the ATII group continued to require 5 or greater vasopressor agents compared to the non-ATII group after propensity score weighting (45.9% vs 12.5%, p < 0.01). SOFA score was the only variable associated with mortality (OR = 1.25, 95% CI, 1.05-1.49; p = 0.01). Patients were considered a "responder" if mean arterial pressure greater than 65 mm Hg at 3 hours after the third vasopressor was initiated. Among the ATII group, 37.5% patients were responders compared to 45.1% responders in the non-ATII group (relative risk = 1.07, 95% CI, 0.6-1.93; p = 0.81). Although previous data support the use of ATII due to its favorable hemodynamic response in patients with distributive shock, there was no observed benefit in mortality or hemodynamic response with ATII as a third-line vasopressor in our study of real-world patients.

Hypotensive effect of Centella asiatica L. extract in acute Angiotensin II-induced hypertension

Centella asiatica L. (C.asiatica) is a plant with a hypotensive effect. Since this effect has several mechanism(s), therefore in the current study we investigated the effects of hydroalcoholic extract of C.asiatica on cardiovascular parameters in acute hypertensive rats. Animals were divided into four groups; 1) control, 2) Angiotensin II (AngII) that received (50 ng/kg) intravenously (i.v.), 3 and 4) two groups of C.asiatica extract (CA100, and CA200 mg/kg). In treated groups, 30 min after injection of the extract, AngII was injected. Cardiovascular parameters were recorded by the power lab system after the cannulation of the femoral artery. The maximum changes (∆) of systolic blood pressure (SBP), mean arterial pressure (MAP) and heart rate (HR) were calculated and used for statistical analysis. In the AngII group, ΔSBP and ΔMAP significantly increased compared to the control group. The HR also decreased compared to the control group but it was not significant. In CA100+AngII group ΔSBP and ΔMAP significantly decreased compared to the AngII. The use of these doses of CA with AngІІ compared to AngІІ alone had a significant effect on the HR. In CA200+AngII group ΔSBP and ΔMAP significantly decreased compared to the AngII. The change of HR in this dose was not significant to the AngII. In a recent study, we concluded that C.asiatica decreased the cardiovascular responses in hypertensive rats received AngII. Also between two doses of C.asiatica did not observe any significant difference. Therefore, one of the most important hypotensive mechanism(s) of the considered plant can be the effect on Renin-angiotensin system.

Role of the renin-angiotensin system in the development of cataract formation in angiotensin-II-induced experimental rats.

Previously, we established several facts regarding hypertension-associated cataractogenesis. As a follow-on study, we evaluated the role of the renin-angiotensin system (RAS) in angiotensin-II (Ang-II)-induced cataract formation in experimental hypertensive rats. Sprague-Dawley male albino rats (150-180 g) were used for the present experiment. The animals were divided into four groups, with six animals in each group. During the 12 weeks of the experimental protocol, the normal group received sterile water (1 ml/kg/day, subcutaneously (sc), and the Ang-II control group received angiotensin (1 mg/kg/day) subcutaneously. The ARB (O) group received olmesartan (2 mg/kg/day) orally, and the ARB (T) group received two drops of olmesartan (5 mM) topically on the cornea; concurrently, both groups were treated with Ang-II (1 mg/kg/day, sc) to induce hypertension. Biweekly, the systolic and the diastolic blood pressures were recorded, and the eyes were examined; moreover, cataractogenic parameters, such as oxidative stress markers and protein contents in the lenses, were evaluated after completion of the experimental protocol. Twelve weeks of olmesartan administered, orally or topically, significantly reduced the progression of cataract formation and restored antioxidants, lipid peroxidation, nitrite content, and protein contents in the lenses of the mice in groups O and T, respectively, as compared with those in the Ang-II control group. On the basis of our results, we conclude that the ocular RAS exacerbates the lenticular oxidative stress that may lead to cataract formation. The results showed that the RAS has an independent and important role in cataract formation under hypertensive conditions.

ELASTASE-2 KNOCKOUT IS ASSOCIATED WITH LESS SUSCEPTIBLE AORTA DILATION IN RESPONSE TO ANGIOTENSIN II STIMULATION IN THE MICE MODEL

Objective: Elastase-2 (ELA-2), a chymotrypsyn-serine protease elastase family member 2A, is expressed in several tissues such as the lungs, heart, liver, kidneys, brain, and vessels. ELA-2 was found to generate angiotensin II (AngII) in arteries and contribute to resistance arteries and vascular remodeling in animal models. It has also been shown that continuous infusion of AngII induces abdominal aortic aneurysm (AAA) in mice. Therefore, we sought to investigate the role of ELA-2 in an aortic dilation, which is a risk factor to AAA development, in a mouse model. Design and method: Male wild type (C57bl/6, WT) and ELA-2 knockout (CELA-2aTm1Bdr; ELA-2 KO) mice were treated with saline or angiotensin II (AngII, 2.28 g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. To evaluate the role of elastase-2 in a AAA development, mice were divided into four groups: WT treated with saline (WT+SAL), ELA-2KO treated with saline (ELA-2KO+SAL), WT treated with AngII (WT+AngII), and ELA-2KO treated with Ang II (ELA-2KO+AngII). The vascular ultrasound (US) was done before treatment and once a week during 28 days of treatment. The abdominal aorta measurements such as maximum aortic diameter, aortic para-renal diameter, aortic infra-renal diameter, and aortic supra-renal diameter were collected. A dilated aorta is a risk factor aortic rupture/aneurysm. Statistical analyses were performed by the Shapiro Wilk Normality test, two-way ANOVA with Sidak's multiple comparisons test. This study is approved by the Ethics Committee (CEUA-131/2019). Results: The most dilated aorta as measured by the maximum aorta diameter was detected in WT+AngII group and was 60% higher than in the WT+Saline (p = 0.01). There was no significant difference in the maximum aorta diameter between ELA-KO+SAL vs. ELA-2KO+AngII (p = 0.8). The measurement of dilation in aortic para-renal and aortic infra-renal showed that AngII induced a dilation in WT+AngII (p &lt; 0.05), while not modified these parameters in ELA-2KO+AngII group. The aortic supra-renal diameter parameters and weight showed no differences between groups. Conclusions: These results suggest that ELA-2KO mice might be less susceptible to develop an aorta dilation. Therefore, Elastase-2 is a candidate factor that contributes to the formation and/or development of abdominal aortic aneurysm.

CHARACTERISING A NOVEL MODEL OF SUPER-IMPOSED PRE-ECLAMPSIA

Objective: The stroke-prone spontaneously hypertensive (SHRSP) rat is a model of chronic hypertension and defective vascular remodelling during pregnancy that can be stressed by administration of angiotensin II (ANGII) to mimic super-imposed pre-eclampsia. This novel model has been tested with doses of 500 ng/kg/min and 1000 ng/kg/min ANGII. The aim of this study was to characterise the pathology of this model with a dose of 750 ng/kg/min to enhance reproducibility and refine the model. Design and method: SHRSP and normotensive Wistar Kyoto (WKY) females were time mated with males of the relevant strain. On gestational day (GD) 10.5 mini osmotic pumps were implanted administering either 0.9% saline or 750 ng/kg/min of ANGII. SHRSPs were split into either SHAM (saline) or ANGII groups. WKY received saline only. At pre-pregnancy (PP), GD 6.5, 14.5 and 18.5 blood pressure, cardiac function and uteroplacental blood flow were measured by tail cuff plethysmography and ultrasound. Urine was collected by metabolic cage at PP, GD6.5 &amp; 18.5 to assess proteinuria. Results: ANGII showed reduced pregnancy-related weight gain vs WKY and SHAM (168.3 ± 3.7 g vs 231.2 ± 3.0 g vs 183.3 ± 5.9 g, p &lt; 0.001). ANGII showed an increased BP when compared to SHAM and WKY (180.9 ± 9.7mmHg vs 127.5 ± 6.5mmHg vs 139.8 ± 7.1 mmHg p &lt; 0.001 GD18.5). ANGII dams showed signs of left ventricular cardiac dysfunction with an elevated relative wall thickness and reduced stroke volume and cardiac output vs WKY (p &lt; 0.05). ANGII and SHAM exhibited impaired uteroplacental blood flow vs WKY at GD18.5 (0.57 ± 0.03au vs 0.62 ± 0.05au vs 0.38 ± 0.02au, p &lt; 0.01). Infusion of ANGII successfully induced proteinuria, measured as urinary albumin:creatinine compared to SHAM and WKY (12.2 ± 8.28 μg/μmol/L vs 0.16 ± 0.01 μg/μmol/L vs 3.9 ± 0.40 μg/μmol/L, p &lt; 0.001). Conclusions: The results presented here show this model has effectively captured the overall disease picture of pre-eclampsia with consistent disease characteristics such as proteinuria, hypertension, maternal cardiovascular impairment and dysregulated uterine artery remodelling. It may serve as a useful tool in the study of pre-eclampsia.

Overexpression of MiR-29b-3p Inhibits Atrial Remodeling in Rats by Targeting PDGF-B Signaling Pathway.

Purpose Studies have found that microRNAs (miRNAs) are closely associated with atrial fibrillation, but their specific mechanism remains unclear. The purpose of this experiment is to explore the function of miR-29b-3p in regulating atrial remodeling by targeting PDGF-B signaling pathway and thereby also explore the potential mechanisms. Methods We randomly divided twenty-four rats into four groups. Caudal intravenous injections of angiotensin-II (Ang-II) were administered to establish atrial fibrosis models. Expressions of miR-29b-3p and PDGF-B were then tested via RT-PCR, western blot, and immunohistochemistry. Binding sites were then analyzed via the bioinformatics online software TargetScan and verified by Luciferase Reporter. We used Masson staining to detect the degree of atrial fibrosis, while immunofluorescence and western blot were used to detect the expressions of Collagen-I and a-SMA. We used immunohistochemistry and western blot to detect the expression of connexin 43 (Cx43). Results In comparison with the Ang-II group, miR-29b-3p was seen to lower the degree of atrial fibrosis, decrease the expression of fibrosis markers such as Collagen-I and a-SMA, and increase the protein expression of Cx43. MiR-29b-3p can lower the expression of PDGF-B, while the Luciferase Reporter showed that PDGF-B is the verified target gene of miR-29b-3p. Conclusions MiR-29b-3p was able to reduce atrial structural and electrical remodeling in the study's rat fibrosis model. This biological function may be expressed through the targeted regulation of the PDGF-B signaling pathway.

Luteolin attenuates angiotensin II‑induced renal damage in apolipoprotein E‑deficient mice.

Renal damage is a common and severe condition encountered in the clinic. Luteolin (Lut) exhibits anti-inflammatory, anti-fibrotic and anti-apoptotic effects. Thus, the present study aimed to investigate the pharmacological effects of Lut on angiotensin II (AngII)-induced renal damage in apolipoprotein E-deficient (ApoE−/−) mice. Male ApoE−/− mice (age, 8 weeks) were randomly divided into the following three groups: i) Control group (n=6); ii) AngII group (n=6); and iii) AngII + Lut group (n=6). Lut was administered by gavage (100 mg/kg/d). ApoE−/− mice were implanted with Alzet osmotic minipumps, filled with either saline vehicle or AngII solution for a maximum period of 4 weeks. After 4 weeks, metabolic characteristics were measured and the histopathological alterations in the kidney tissue were observed. The metabolic characteristics of blood creatinine (CRE) levels were lower in the AngII + Lut group compared with in the AngII group. The expression levels of collagen I and III were lower in the kidney tissues of the AngII + Lut group compared with the corresponding tissues of the AngII group. The gene expression levels of IL-1β, IL-6, TNF-α and IL-10 were also suppressed in the kidney tissues of the AngII + Lut group compared with those in the corresponding tissues of the AngII group. Furthermore, the AngII + Lut group exhibited markedly increased LC3 protein expression and notably decreased p62 protein expression in the kidney tissues compared with the expression levels in the AngII group. The data demonstrated that Lut attenuated AngII-induced collagen deposition and inflammation, while inducing autophagy. Collectively, the results suggested that Lut treatment exhibited a exerted effect on AngII-induced renal injury in ApoE−/− mice.

Abstract 15127: Isorhamnetin Reverses Angiotensin Ii-induced Atrial Fibrillation Vulnerability Through Electrophysiological and Structural Reverse Remodeling in Mice

Background: Isorhamnetin (ISO), a natural flavonoid compound, has been shown to have strong antioxidant and antifibrotic effects in vivo and in vitro; however, no report has been shown on the effect of ISO on arrhythmic disorders. This study aimed to investigate the effect of ISO on angiotensin-II (Ag-II) induced atrial fibrillation (AF) in mice. Methods: Wild-type male mice (C57BL/6J, 8 weeks old) were assigned in 3 groups as follows: control group (Cont), Ag-II group treated with Ag-II and Ag-II &amp; ISO group treated with Ag-II and ISO. Ag-II (1000 ng/kg/min) was continuously administered using an implantable osmotic pump for 2 weeks, and ISO (5 mg/kg) was administered intraperitoneally one week before starting Ag-II administration. We performed AF induction and electrophysiologic study via transvenous electrode catheter and Ca 2+ imaging with isolated cardiomyocyte. We also assessed the gene expression levels of AF-related molecules, and histological examination of atrial fibrosis. Results: Compared with Cont, AF inducibility was dramatically increased by Ag-II and significantly decreased by ISO. AF duration was also remarkably prolonged by Ag-II and significantly reduced by ISO. Atrial effective refractory period (A-ERP) (BCL=150msec) was reduced by Ag-II and recovered by ISO. Incidences of diastolic intracellular Ca 2+ abnormal activities (sarcoplasmic reticulum [SR] Ca 2+ leakage) was observed in Ag-II group; however, ISO treatment eliminated these abnormalities. Ag-II induced elevated expression of fibrosis-related molecules (Col1a1, Tgfb1 and Tgfb2) and Ca 2+ -handling related molecules (Camk2 and Ryr2), those were partially normalized by ISO. Histological examination revealed that cell size and the fibrosis ratio were increased by Ag-II, and significantly attenuated by ISO. Conclusion: These results suggest that ISO prevented against Ag-II induced AF vulnerability through both electrophysiological and structural reverse remodeling.

Ethyl Acetate and Aqueous Fractions of Ziziphus jujuba Prevent Acute Hypertension Induced by Angiotensin II in Rats.

The effect of hydroalcoholic extract of Ziziphus jujuba (ZJ) on hypertension has been reported previously. This experiment investigates the effect of two ethyl acetate (EA, a polar and semi-polar compound) and aqueous fractions (AQ, a polar compound) of ZJ extract on cardiovascular parameters in acute hypertension induced by angiotensin II (AngII). Rats were randomly divided into following groups (n=7 in each group): 1) Control; 2) AngII (50 ng/kg); 3) Losartan (LOS, 30 mg/kg) + AngII; 4, 5) ethyl acetate fraction (EA150 and EA300 mg/kg) + AngII and 6, 7) aqueous fraction (AQ150 and AQ300 mg/kg) + AngII. Rats were treated with both fractions and LOS orally for four weeks and in the experiment day (28th) AngII intravenously injected and cardiovascular parameters (Systolic Blood Pressure (SBP), Mean Arterial Pressure (MAP) and Heart Rate (HR)) directly were recorded by a power lab system. AngII could significantly increase SBP and MAP (P<0.001) and decrease HR with respect to the control and these responses were attenuated by LOS. The SBP and MAP in both doses of EA+ AngII and the higher dose of AQ fractions + AngII were significantly lower than the AngII group (P<0.05 to P<0.001). Bradycardia induced by AngII was also reduced by LOS and both fractions. The comparison of two fractions also showed that the effect of EA fraction is greater than the AQ. This study indicates that both fractions of the ZJ extract have a beneficial effect on hypertension. Because effect of EA was greater than AQ, we suggested that antihypertensive effects of ZJ mediated polar and nonpolar compounds.

Angiotensin II induces RAW264.7 macrophage polarization to the M1‑type through the connexin 43/NF‑κB pathway

Angiotensin II (AngII) serves an important inflammatory role in cardiovascular disease; it can induce macrophages to differentiate into the M1-type, produce inflammatory cytokines and resist pathogen invasion, and can cause a certain degree of damage to the body. Previous studies have reported that connexin 43 (Cx43) and NF-κB (p65) are involved in the AngII-induced inflammatory pathways of macrophages; however, the mechanisms underlying the effects of Cx43 and NF-κB (p65) on AngII-induced macrophage polarization have not been determined. Thus, the present study aimed to investigate the effects of Cx43 and NF-κB (p65) on the polarization process of AngII-induced macrophages. The macrophage polarization-related proteins and mRNAs were examined by flow cytometry, western blotting, immunofluorescence, ELISA and reverse transcription-quantitative PCR analyses. RAW264.7 macrophages were treated with AngII to simulate chronic inflammation and it was subsequently found that AngII promoted RAW 264.7 macrophage polarization towards the M1-type by such effects as the release of inducible nitric oxide synthase (iNOS), tumour necrosis factor (TNF)-α, IL-1β, the secretion of IL-6, and the expression of M1-type indicators, such as CD86. Simultaneously, compared with the control group, the protein expression levels of Cx43 and phosphorylated (p)-p65 were significantly increased following AngII treatment. The M1-related phenotypic indicators, iNOS, TNF-α, IL-1β, IL-6 and CD86, were inhibited by the NF-κB (p65) signalling pathway inhibitor BAY117082. Similarly, the Cx43 inhibitors, Gap26 and Gap19, also inhibited the expression of M1-related factors, and the protein expression levels of p-p65 in the Gap26/Gap19 groups were significantly decreased compared with the AngII group. Altogether, these findings suggested that AngII may induce the polarization of RAW264.7 macrophages to the M1-type through the Cx43/NF-κB (p65) signalling pathway.

P5443NOD2 knock down worsens diastolic dysfunction in murine angiotensin II-induced heart failure

Abstract Background Heart failure with preserved ejection fraction (HFpEF) is associated with cardiac inflammatory responses, indicating a potential role of the immune system in the pathology of diastolic dysfunction. The cytoplasmatic pattern recognition receptor, nucleotide binding oligomerization domain 2 (NOD2) belongs to the innate immune system and induces among others the NLRP3 inflammasome, known to be involved in myocarditis and coronary heart disease. Purpose The aim of this study was to explore the role of NOD2 in Angiotensin II (AngII)-induced diastolic heart failure. Methods In NOD2−/− knock down and C57Bl6/j-wild type (WT) mice, diastolic dysfunction was induced by subcutaneous administration of 1.4mg/kg*day–1 AngII. Twenty-one days after first AngII administration, left ventricular (LV) function was evaluated by pressure tip catheter. Cardiac fibrosis, inflammation, and the expression of NOD2 and the NLRP3 component Apoptosis-associated speck like protein containing a caspase recruitment domain (ASC) were determined via immunohistochemistry, real-time PCR or Western Blot. Results LV NOD2 mRNA expression was 2.3-fold (p&lt;0.0005) and 1.9-fold (p&lt;0.0005) lower in NOD2−/− control and NOD2−/− AngII mice compared to their respective WT littermates. In parallel, LV protein expression of the downstream NLRP3 component Apoptosis-associated speck like protein containing a caspase recruitment domain (ASC) was 1.5-fold (p&lt;0.05) lower in NOD2−/− AngII mice versus WT AngII mice, whereas LV protein IL-1β levels were unchanged. LV diastolic dysfunction was more pronounced in NOD2−/− AngII mice versus WT AngII mice, as displayed by a 19% (p&lt;0.05) increased LV relaxation time and 24% (p&lt;0.057) impaired dP/dtmin, with no changes in the ejection fraction (EF: NOD2−/− AngII 72.5%±5.4 versus WT AngII 65.6±3.5). In parallel, LV presence of CD68-positive cells was 1.8-fold (p&lt;0.05) higher in NOD2−/− AngII compared to WT AngII mice. Concomitantly, NOD2−/− AngII mice displayed 1.3-fold (p&lt;0.05) and 1.7-fold (p&lt;0.05) higher LV mRNA expression of the chemokine macrophage inflammatory protein (MIP)-2 and monocyte chemotactant protein (MCP)-1 compared to WT AngII mice, respectively. Furthermore, cardiac interstitial fibrosis in NOD2−/− mice with AngII-induced diastolic dysperformance was more pronounced versus the WT AngII group, as indicated by a 2.0-fold (p&lt;0.0005), 2.0-fold, and 1.6-fold (p&lt;0.05) higher LV ColI/ColIII ratio, and TGF-β and TIMP-1 mRNA expression, respectively. Conclusion NOD2−/− deteriorates LV diastolic dysfunction and worsens pathophysiological key mechanisms in mice with AngII-induced diastolic heart failure.

Abstract 046: Chronic Nicotine Inhalation Promotes the Development of Hypertension

While smoking is a proven risk factor for stroke and heart attacks, whether it contributes to the development of hypertension is still unclear. Nicotine inhalation is thought to activate the sympathetic nervous system and could contribute to the development of dysautonomia and blood pressure (BP) dysregulation. The purpose of this study was to investigate a possible relationship between chronic nicotine inhalation and the development of hypertension. C57BL/6 mice (male, 8-12 weeks of age) were exposed to air or nicotine vapor (daily, 12 h on/off) for 8 weeks. BP was recorded weekly for 24 h (telemetry). Nicotine exposure was assessed by weekly measurement of serum cotinine levels, which showed an average of 599.0 ±54.3 ng/ml in nicotine-exposed mice. Nicotine exposure induced a time-dependent increase in systolic BP. Notably, 24-h BP recordings showed that by the end of the 7 th week, systolic BP of nicotine-exposed mice was more often in the hypertensive zone (as defined by the area under the curve [AUC] above the 130 mmHg threshold within a 24-h recording) compared to their air-exposed counterparts (AUC: 555 ±299 vs. 112 ±30, P=0.012 , n=12). This hypertensive response was validated in angiotensin-II (Ang-II)-infused mice (450 ng/kg/min, s.c., AUC: 1358 ±939 vs. 112 ±30, P&lt;0.001 , n=5). At the end of nicotine exposure, urinary norepinephrine (NE) showed significant increase in both nicotine (108.9 ±9.8 vs. 79.53 ±5.7 ng/1ng creatinine, P=0.018 , n=9) and Ang-II groups (114.0 ±14 vs. 79.53 ±5.7 ng/1ng creatinine, P=0.016 , n=9), suggesting increased sympathetic activity in those mice. In addition, mice with global deletion of angiotensin converting enzyme type 2 (ACE2) showed a dramatic elevation in urinary NE level after nicotine exposure (157.8 ±8.5 vs. 79.53 ±5.7 ng/1ng creatinine, P&lt;0.001 , n=9). These data suggest that ACE2 might be protective against nicotine inhalation-mediated rise in sympathetic activity. In summary, chronic nicotine inhalation promotes the development of hypertension, and this could be mediated through the elevated activity of sympathetic nervous system. Experiments are ongoing to confirm sympatho-excitation and a possible involvement of the renin-angiotensin system in chronic nicotine inhalation-induced hypertension.