Variations In Angiotensin Research Articles

Genetic Variation in Angiotensin II Type 1 Receptor Is Linked to Lipid Levels and Hepatic Steatosis in Alcohol-Associated Liver Disease, but Not to Cirrhosis or Hepatocellular Carcinoma

Background: Development of cirrhosis and hepatocellular carcinoma (HCC) in patients with high alcohol intake is modulated by genetic predispositions. Genetic variation in angiotensin II type 1 receptor (AGTR1) has been described as a risk factor for non-alcoholic fatty liver disease in Asian patients. Methods: We analysed Caucasian patients with alcohol–associated cirrhosis without (n = 238) and with (n = 339) HCC, healthy controls (n = 200), and HCV–infected cirrhotic patients with and without HCC (n = 263) for association with the polymorphisms rs3772622 and rs2276736 in AGTR1. Results: Rs2276736 in AGTR1 was associated with both low–density lipoprotein (LDL) cholesterol levels and hepatic steatosis in patients with alcohol–associated liver disease. The distribution of genotypes for both rs3772622 and rs2276736 in AGTR1 were comparable between controls, cirrhosis patients, and those with HCC. Minor allele frequencies were 32% (44%) in healthy controls, 35%/34% (46%/45%) in alcohol–associated liver disease without/with HCC and 31%/38% (43%/39%) in HCV cirrhosis and HCV HCC, respectively. The genotype of the most important genetic risk factor for fatty liver disease, PNPLA3 I148M, did not interact with the AGTR1 polymorphisms. Conclusion: Genetic variation in AGTR1, although associated with blood lipid levels and hepatic steatosis, is not a risk factor for alcohol–associated cirrhosis or HCC in Caucasians.

Angiotensin II Activates the Expression of Inflammatory Markers and the Migration of Inflammatory Cells into the Aorta of Normotensive Mice

IntroductionAngiotensin II exerts important physiological functions on cardiovascular system homeostasis and may mediate actions leading to inflammatory responses. These actions lead to the activation of vascular smooth muscle cells (CMLVs) as well as the endothelium, in order to produce reactive oxygen species, inflammatory cytokines, chemokines and adhesion molecules inducing diapedesis of cells of myeloid origin. In this context, variations in Angiotensin II concentrations could occur in the body, leading to discrete increases that do not directly and immediately interfere with blood pressure but could stimulate the recruitment and activation of myeloid cells capable of initiating local inflammatory responses. Such a situation would provide important information for triggering a chronic process on the mechanisms of maintaining blood pressure and potentially leading to cardiovascular disease. This study aimed to verify the ability of angiotensin II to induce an inflammatory response in the aorta and if there is a relation with variations of arterial pressure, even if discrete.MethodsFor this, C57Bl/6 mice treated with saline solution (0.9%, control group) or Angiotensin II (30ng, Ang II group) were used. The animals were cannulated in the carotid artery and jugular vein, and 48 hours later PA and HR levels were recorded at baseline and after administration of saline or Ang II at 30 min, 1, 2, 6, 12 and 24 h. The evaluation of the baroreflex sensitivity was performed after administration of phenylephrine and sodium nitroprusside (100 and 150 ng). The evaluation of the inflammatory reaction in the aorta was performed by immunohistochemistry, using IL1‐β, TGF‐β, iNOS as inflammatory markers and CD45 as a marker of macrophages. The evaluation of α‐actin was performed in order to demonstrate a possible change in CMLV phenotype.ResultsAt the end of the treatments, we verified that there was no change in blood pressure or heart rate. In addition, the treatment did not alter the baroreflex sensitivity. A biphasic response was observed both for IL1‐β and TGF‐β expression and also for the presence of CD45 positive cells, with an acute increase (between 30 and 60 minutes) and another more chronic increase, between 24 and 48 hours. Positive staining for iNOS increased in the earlier period (30 minutes) in perivascular adipose tissue and in a longer period (24 hours) in tunica adventitia. Immunoblotting to α‐actin showed no alterations, suggesting that the applied dose of angiotensin II does not alter the aortic CMLV phenotype.ConclusionThe results suggest that angiotensin II, even at doses that do not alter blood pressure, is capable of inducing the expression of inflammatory markers and the migration of inflammatory cells into the aorta of normotensive mice. Thus, angiotensin II may be considered to be capable of increasing the propensity to develop a cardiovascular injury, even in normotensive individuals.Support or Funding InformationThis research was funded by Coordenação de Apoio a Pesquisa (CAPES) and São Paulo's state research funding agency Foundation (FAPESP).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Early Adoption of Sacubitril/Valsartan for Patients With Heart Failure With Reduced Ejection Fraction: Insights From Get With the Guidelines–Heart Failure (GWTG-HF)

ObjectivesThe aim of this study was to assess the prevalence and variation in angiotensin receptor/neprilysin inhibitor (ARNI) prescription among a real-world population with heart failure with reduced ejection fraction (HFrEF). BackgroundThe U.S. Food and Drug Administration approved sacubitril/valsartan for patients with HFrEF in July 2015. Little is known about the early patterns of use of this novel therapy. MethodsThe study included patients discharged alive from hospitals in Get With the Guidelines–Heart Failure (GWTG-HF), a registry of hospitalized patients with heart failure, between July 2015 and June 2016 who had documentation of whether ARNIs were prescribed at discharge. Patient and hospital characteristics were compared among patients with HFrEF (ejection fraction ≤40%) with and without ARNI prescription at discharge, excluding those with documented contraindications to ARNIs. To evaluate hospital variation, hospitals with at least 10 eligible hospitalizations during the study period were assessed. ResultsOf 21,078 patients hospitalized with HFrEF during the study period, 495 (2.3%) were prescribed ARNIs at discharge. Patients prescribed ARNIs were younger (median age 65 years vs. 70 years; p < 0.001), had lower ejection fractions (median 23% vs. 25%; p < 0.001), and had higher use of aldosterone antagonists (45% vs. 31%; p < 0.001) at discharge. At the 241 participating hospitals with 10 or more eligible admissions, 125 (52%) reported no discharge prescriptions of ARNIs. ConclusionsApproximately 2.3% of patients hospitalized for HFrEF in a national registry were prescribed ARNI therapy in the first 12 months following Food and Drug Administration approval. Further study is needed to identify and overcome barriers to implementing new evidence into practice, such as ARNI use among eligible patients with HFrEF.

Genetic variation in angiotensin II type 2 receptor gene influences extent of left ventricular hypertrophy in hypertrophic cardiomyopathy independent of blood pressure

Hypertrophic cardiomyopathy (HCM), an inherited primary cardiac disorder mostly caused by defective sarcomeric proteins, serves as a model to investigate left ventricular hypertrophy (LVH). HCM manifests extreme variability in the degree and distribution of LVH, even in patients with the same causal mutation. Genes coding for renin-angiotensin-aldosterone system components have been studied as hypertrophy modifiers in HCM, with emphasis on the angiotensin (Ang) II type 1 receptor (AT(1)R). However, Ang II binding to Ang II type 2 receptors (AT(2)R) also has hypertrophy-modulating effects. We investigated the effect of the functional +1675 G/A polymorphism (rs1403543) and additional single nucleotide polymorphisms in the 3' untranslated region of the AT(2)R gene (AGTR2) on a heritable composite hypertrophy score in an HCM family cohort in which HCM founder mutations segregate. We find significant association between rs1403543 and hypertrophy, with each A allele decreasing the average wall thickness by ~0.5 mm, independent of the effects of the primary HCM causal mutation, blood pressure and other hypertrophy covariates (p = 0.020). This study therefore confirms a hypertrophy-modulating effect for AT(2)R also in HCM and implies that +1675 G/A could potentially be used in a panel of markers that profile a genetic predisposition to LVH in HCM.

Angiotensin-Converting Enzyme and Endothelial Constitutive Nitric Oxide Synthase Polymorphisms in Turkish Renal Transplant Population and Possible Influence on Renal Artery Atherosclerosis and Graft Survival

Background Renal transplant recipients are prone to accelerated atherosclerosis secondary to immunsuppressants, which may decrease graft survival. We sought to analyze the effects on renal graft survival of atherosclerotic degeneration in the renal artery and the influence of angiotensin-converting enzyme (ACE) endothelial constitutive nitric oxide synthase (ecNOS) gene polymorphisms. Methods and patients Thirty three renal transplant recipients (25 men) of mean age 28.4 ± 9.6 years, received organs from 11 living related donors and were followed for at least 36 months. Genotyping was performed for the insertion/deletion ACE (I/D), angiotensin (AGT) (M→T, 235), angiotensine 1 receptor (A→C, 1166), angiotensin 2-receptor (A→G, 1223), and ecNOS (b→a, intron4) gene polymorphisms. Renal artery biopsies were performed during transplantation surgery to analyze the presence of atherosclerosis. Results Pathological examination indicated that 18 donor specimens and nine recipient specimens had atherosclerotic degeneration. Survival analysis (36 months) indicated that graft survival rates of recipients who had atherosclerosis in the renal artery and who received an organ from donors with an atherosclerotic renal artery were shorter than in their counterparts ( P = .02, P = .04, respectively). Comparison of genetic variations of recipients revealed that CC/TC variation of AGT was higher in patients with atherosclerosis (81% vs 53%, P = .03). There was no significant difference between groups in means of other gene polymorphisms. Conclusion Renin-angiotensin system gene polymorphism analysis of patients in renal transplantation waiting list may provide information about allograft survival and posttransplant atherosclerotic degeneration at graft vasculature of young transplant recipients.

Angiotensin II type I receptor gene and myocardial infarction: tagging SNPs and haplotype based association study. The Beijing atherosclerosis study.

The present study aimed to assess the effect of haplotype variation in angiotensin II type I receptor (AGTR1) gene on the risk of myocardial infarction (MI) in Chinese males. We used 48 patients to identify the putative functional polymorphisms in AGTR1 gene by direct sequencing. The program tagSNPs was used to identify an optimal set of tagging single nucleotide polymorphisms (SNPs). These selected SNPs were then genotyped in 419 male patients with MI and 400 age-matched male controls. The program haplo.stats was used to investigate the relationship between the haplotypes and MI. Sixteen polymorphisms in AGTR1 gene were identified. Based on the linkage disequilibrium pattern among these SNPs, six polymorphisms, SNP1, SNP6-SNP7 and SNP13-SNP15, were selected as haplotype tagging SNPs and further genotyped. Single SNP analyses indicated that the SNP1, SNP6 and SNP13 were significantly associated with MI, adjusted for covariates. Haplotype-based association analyses identified the frequency of haplotype AGATAA was lower in cases than in controls (P = 0.006). In comparison, three haplotypes (AAATAA, TAGCAA and AAACAG) were found to significantly increase the risk of MI with adjusted odds ratio equal to 1.33, 1.75 and 2.64, respectively (P = 0.029, 0.026 and 0.015). Our study suggests that common genetic variations in the AGTR1 gene may affect the risk of MI in Chinese males, and that there might be several functional variants in AGTR1 gene and the combined effect of these variants seemed to have a larger effect on the risk of MI in Chinese males.

INFLUENCE OF CIRCADIAN TIME AND AGE ON GLOMERULAR ANGIOTENSIN II RECEPTORS IN NORMOTENSIVE SPRAGUE-DAWLEY AND TRANSGENIC HYPERTENSIVE TGR(mREN2)27 RATS

In male heterozygous transgenic hypertensive rats, TGR(mREN2)27 (TGR), exhibiting an inverse blood pressure profile and in normotensive Sprague-Dawley (SPRD) controls, the density and affinity of angiotensin II receptors were determined at six circadian times in glomeruli of animals 11 weeks old kept under light-dark 12h:12 (LD 12:12) conditions. Angiotensin II receptors were also studied in rats 18–20 weeks old of both strains at 2h after light onset. As a measure of renal excretory functions, diuresis, creatinine, and protein excretion were monitored using metabolic cages. The expression of angiotensin II receptor mRNA was determined in renal arteries 2h–4h after light onset. The following results were obtained: Renal excretory functions showed significant daily variation, with higher excretion rates in the dark span in both TGR and SPRD rats. No circadian phase dependency was found in the glomerular angiotensin II receptors in both rat strains. However, receptor density was significantly lower in TGR than in SPRD rats. In both strains, receptor number increased with aging. In renal arteries, the angiotensin II receptor mRNA of the main receptor subtype AT1A was neither strain nor age dependent, AT1B- and AT2-receptor mRNAs were significantly lower in TGR than SPRD rats. In conclusion, the results demonstrate that the overactive renin-angiotensin system in TGR rats led to a down-regulation of glomerular angiotensin II receptors that was not accompanied by a down-regulation of the mRNA of the dominant AT1A- receptor subtype. Circadian short-term variations in blood pressure in both TGR and SPRD rats are not reflected by daily variation in angiotensin II receptor density of renal glomeruli or by variation in receptor expression in renal vascular tissue. (Chronobiology International, 18(3), 447–459, 2001)

Neurohormonal reactivation in heart failure patients on chronic ACE inhibitor therapy: a longitudinal study.

Angiotensin Converting Enzyme inhibitors reduce mortality in heart failure. One therapeutic mechanism is believed to be the reduction of circulating angiotensin II and aldosterone. However, the Renin-Angiotensin-Aldosterone axis (RAAS) is not uniformly suppressed during therapy for heart failure. This effect has been referred to as 'angiotensin II reactivation' and 'aldosterone escape' and their reactivation may herald clinical deterioration. In the CONSENSUS I trial, correlations were seen between mortality, and angiotensin II and aldosterone. Furthermore, mortality was lower in those with good angiotensin II suppression. Therefore, neurohormonal elevation despite adequate treatment may associate with a poorer prognosis. To follow chronic heart failure patients on ACE inhibitors for 18 months to assess whether or not angiotensin II and aldosterone reactivation are progressive with time, whether reactivation of both occurs simultaneously, and whether different ACE inhibitors have different neurohormonal profiles. We studied 22 patients (M/F 19:3, 72.5+/-7 years) on stable ACE inhibitors. Five times, in 18 months, samples were taken for neurohormones and ACE activity. Mean levels of neurohormones were remarkably stable over time, although captopril takers had generally higher angiotensin II, but lower aldosterone and renin. Aldosterone 'escape' (> 80 pg/ml) occurred in 13/97 samples (13.5%), in 5/22 (23%) individuals. Angiotensin II was elevated > or =10 pg/ml in 8/102 samples (8%), in 6/22 (27%) individuals. Four subjects had isolated angiotensin II reactivation, and three had aldosterone escape alone. On regression analyses between neurohormones in captopril takers there were significant correlations between; renin and angiotensin II (r = 0.62; P<0.02); angiotensin II and aldosterone (r = 0.6; P<0.02); and renin and aldosterone (r = 0.92; P<0.00001). In stable heart failure patients un-suppressed levels of angiotensin II and aldosterone occur despite therapy, but they are not necessarily progressive, nor simultaneous. Furthermore, contemporaneous serum ACE activity makes it unlikely the data presented reflects poor compliance. The results suggest that captopril takers may have different neurohormonal profiles, i.e. higher angiotensin II, and also better correlations between RAAS components, compared to longer acting preparations, although the numbers are small. Our data supports that of Swedberg et al. who showed reductions in both aldosterone and angiotensin II due to ACE inhibitor therapy, but no correlation between ACE activity and angiotensin II and only a limited correlation (r = 0.37) between angiotensin II and aldosterone. This suggests that the interaction between the components of the renin-angiotensin system is not simple and linear. The fact that each phenomenon appears to occur in isolation means that neurohormonal monitoring of individual could provide useful information to direct additional therapy. The RALES study has demonstrated reduced mortality from the addition of spironolactone to an ACE inhibitor emphasising the benefit of enhanced suppression of aldosterone in heart failure. Captopril may be less effective at suppressing the RAAS due to its short duration of action which would logically be associated with a more fluctuating pattern of ACE inhibition. In the presence of high levels of renin and angiotensin I even small differences in ACE activity will produce large variations in angiotensin II levels. Further studies should be directed at understanding the different mechanisms behind angiotensin II and aldosterone generation during ACE inhibition.

Evaluation of the angiotensin challenge methodology for assessing the pharmacodynamic profile of antihypertensive drugs acting on the renin-angiotensin system.

The performance of the experimental paradigm of angiotensin challenges with continuous non-invasive blood pressure measurement was evaluated. Angiotensin dose-response relationships were characterized, along with the influence of clinical covariates. The stability of angiotensin-induced peaks and the variability of the angiotensin doses were assessed. Finally, the predictive value of studies based on angiotensin challenges to determine drug doses effective in therapeutics was evaluated. The data were gathered from 13 clinical studies on nine angiotensin II receptor antagonists, one ACE inhibitor and one dual ACE-NEP inhibitor, using Finapres for measuring the response to exogenous angiotensin challenges. Modelling of angiotensin dose-response curves and determination of the inter and intrasubject variability were performed by nonlinear regression (NONMEM). The different sources of variations in angiotensin I and II doses and angiotensin-induced peaks were evaluated by analyses of variance. The dose of ACE inhibitors and angiotensin II receptor antagonists inhibiting blood pressure increase by at least 75%, as measured by this method, was chosen for comparison with the labelled starting dose. Angiotensin challenges exhibited a clear dose-response relationship which can be characterized both by an Emax or a log linear model. The log linear model gave an average systolic/diastolic response of 24+/-6/20+/-5 mmHg for a unit dose of 1 microgram of angiotensin II equivalents, and an increase of 6/6 mmHg for each doubling of the dose. The angiotensin ED50 calculated values were 0.67 microgram for systolic and 0.84 microgram for diastolic blood pressure. The angiotensin doses for eliciting a given response and the angiotensin induced peaks were fairly constant between period and subject, but vary significantly between studies. Based on an inhibition of blood pressure by 75%, the agreement was good between the doses of ACE inhibitors and angiotensin receptor antagonists predicted from studies using the methodology of angiotensin challenges and the doses shown to be clinically efficacious, in spite of high intersubject and intrasubject variabilities. This experimental method represents a valid surrogate for the therapeutic target and a useful tool for the pharmacokinetic and pharmacodynamic profiling of drugs acting on the renin-angiotensin system.

Diurnal variation in angiotensin sensitivity in pregnancy

OBJECTIVE: Our purpose was to study the diurnal variation in angiotensin II sensitivity. STUDY DESIGN: Angiotensin sensitivity tests were performed at 9 AM and at 2 PM in 12 normotensive pregnant women, with each woman serving as her own control. RESULTS: In all patients the effective pressor dose was higher in the afternoon. CONCLUSION: We suggest the greater sensitivity to angiotensin in the morning is related to an intrinsic circadian variation in vascular reactivity. When the result of an angiotensin sensitivity test is interpreted, the time of day it is performed should be taken into account. (A M J O BSTET G YNECOL 1996;174:259-61.)

Angiotensin II facilitates tricyclic antidepressant-induced changes in QRS-duration in the rat.

Experimental evidence indicates that angiotensin II can modulate sodium channel and gap junction function. This raises the possibility that variations in angiotensin II could alter the effect of drugs that act on these mechanisms. In this study, the influence of changing salt status and angiotensin II activity has been investigated by evaluating the QRS prolonging effects of the sodium channel blocking drug, desmethylimipramine. In control rats with a normal salt intake, intravenous infusion of desmethylimipramine (0.8 mg/kg/min) over 60 min increased QRS duration over time to 150% of control by 60 min; mean arterial blood pressure and pulse rate were decreased. In salt-deplete rats, the response to desmethylimipramine was similar to controls for 30 min. Thereafter, QRS duration increased more rapidly than controls. In rats on a high salt diet, the same desmethylimipramine infusion produced no change in QRS duration for 30 min, despite equivalent reductions in mean arterial blood pressure. Thereafter, QRS duration increased, reaching values similar to control by 60 min. In rats on a normal salt diet pretreated with captopril, there was a similar blunting of the QRS response to desmethylimipramine to that observed in salt-loaded rats. The QRS response to desmethylimipramine and salt-loaded rats on normal salt diets receiving captopril returned to the control pattern after a subpressor infusion of angiotensin II (3 ng/min), while a higher rate of angiotensin II (10 ng/min) further enhanced the QRS prolonging effect of desmethylimipramine. These data demonstrate that endogenous angiotensin II contributes to the regulation of the cardiac electro-physiological response to DMI.

Antihypertensive contribution of sodium depletion and the sympathetic axis during chronic angiotensin II converting enzyme inhibition

The known physiological adaptation of cardiovascular sensitivity to variations in angiotensin II (Ang II) levels would predict that the blood pressure (BP)-lowering effect of Ang II inhibition might be at least partly counterbalanced by enhanced Ang II reactivity. Therefore, factors other than Ang II inhibition per se may contribute to the antihypertensive mechanisms of angiotensin converting enzyme (ACE) inhibitors. In order to further investigate this, the body sodium-blood volume state as well as the pressor reactivity to infused Ang II or norepinephrine (NE) were assessed in 12 normal subjects and 16 patients with essential hypertension given a placebo, and after 6 weeks of intervention with enalapril (20-40 mg/day). Enalapril produced in both groups similar falls in plasma ACE activity (P less than 0.0001) and upright plasma aldosterone (P less than 0.01), and a rise in plasma renin activity (PRA; P less than 0.05). BP decreased from 156/107 +/- 3/2 (mean +/- s.e.m.) to 142/94 +/- 5/3 mmHg (P less than 0.001) in the hypertensives and from 118/84 +/- 4/2 to 111/73 +/- 4/3 mmHg (P less than 0.01) in the normal subjects. In the hypertensive patients only, the Ang II pressor reactivity relative to Ang II plasma levels during Ang II infusion was increased (P less than 0.01), while the NE pressor reactivity relative to NE plasma levels during NE infusion (P less than 0.01) as well as the exchangeable body sodium (-5%, P less than 0.001) were reduced significantly. Blood and plasma volume, levels of plasma atrial natriuretic factor and catecholamines, and the heart rate and its response to isoproterenol were unchanged in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of short-term upright posture on plasma angiotensin II in man.

The effect of upright posture on radioimmunologically measured venous plasma angiotensin II was studied in healthy volunteers, using active (continuous walking) and passive (head-up tilting) types of upright posture. Blood samples were drawn 1, 3, 10, 30 and 90 minutes after assumption of an upright posture. Significantly increased concentrations of angiotensin II were found 10 minutes after the change of posture. In the active test the initial rise was more marked, whereas at 90 minutes significantly more angiotensin II was found in the passive test. The initial rise in the active test was slightly slower in subjects over 60 years of age. During the conditions used the diurnal variation of angiotensin II was not found to affect markedly the response of angiotensin II to upright posture. The present data suggest that angiotensin II does not play any significant role in the maintenance of blood pressure right after the change of posture from supine to upright. Later, angiotensin II is obviously linked to t...