Blood Pressure-independent Manner Research Articles

Non-steroidal mineralocorticoid receptor antagonist, finerenone, attenuates obesity- and hypertension-induced cardiomyocyte hypertrophy in a blood pressure-independent manner

Abstract Background The FIGARO-DKD study revealed that the non-steroidal mineralocorticoid receptor antagonist (MRA), finerenone improved cardiovascular outcomes in patients with type 2 diabetes. The usefulness of MRA for heart failure with reduced ejection fraction (HFrEF) has been established, however, it is not clear for heart failure with preserved ejection fraction (HFpEF). Furthermore, pathophysiological mechanisms of HFpEF itself has not been clarified, and the mechanism of action of MRA based on the pathophysiology peculiar to HFpEF needs to be verified. Purpose The cardioprotective effects of finerenone were investigated using the HFpEF mouse model. Methods As an HFpEF mouse model, we used the 15 weeks combined stress model of obesity and hypertension. (Schiattarella et. al., Nature 2019). High fat diet ingestion and 0.5 g/L of Nω-nitro-L-arginine methyl ester (L-NAME) drinking were loaded. As a drug administration experiment, with combined stress for 10 weeks, placebo or 10 mg/kg/day finerenone was administered for the last two weeks. After loading, body weight, blood pressure, heart weight, myocardial cross-sectional areas(CSAs), and mitochondrial protein acetylation were evaluated. Results As previously reported, combined stress induced body weight (BW) gain and blood pressure (BP) elevation (BW: control 24.4±1.5 g, combined stress 32.5±5.2 g; P = 0.0007, systolic BP: control 100.6±11.5mmHg, combined stress 113.6±12.6mmHg; P = 0.026). Histological analysis revealed the significant enlargement of cardiomyocyte CSAs in the combined stress group (control 8.0±2.5 micron2, combined stress 12.1±3.1 micron2; P<0.0001). In addition, we found mitochondrial protein acetylation (acetylated lysine; AcK) level, adjusted by ubiquinol-cytochrome c reductase, rieske iron-sulfur polypeptide 1 (UQCRFS1) was also enhanced in the combined stress model (AcK/UQCRFS1: control 1.0±0.33, combined stress 2.5±0.28; P = 0.0034). Subsequently, finerenone administration did not show remarkable reduction of systolic BP compared to the placebo group (placebo 144±34.3 mmHg, finerenone 135.8±13.4 mmHg; P = 0.63). However, histological analysis revealed significant reduction of cardiomyocyte CSAs in the finerenone group (placebo 8.7±1.7 micron2, combined stress 7.9±1.2 micron2; P = 0.0247). Furthermore, mitochondrial protein hyperacetylation was also ameliorated in the finerenone group (AcK/UQCRFS1: placebo 2.4±0.3, finerenone 1.7±0.32; P = 0.044). Conclusion In the HFpEF murine model, finerenone improved cardiac hypertrophy independent of blood pressure. In addition, mitochondrial protein hyperacetylation, which involves mitochondrial dysfunction, was also alleviated by finerenone administration. Previous our work demonstrated that fatty acid stress hyperacetylated mitochondrial proteins and induced the mitochondrial dysfunction (Arima et. al., Nature Metabolism 2021). Our findings indicate that the cardioprotective effects of finerenone may also affect mitochondrial function.

PS-B07-5: EXERCISE TRAINING UPREGULATES FATTY ACID B;-OXIDATION WITH INCREASING PGC-1A AND PPARA IN THE KIDNEY OF DAHL SALT-SENSITIVE RATS

Objective: Exercise training (Ex) has anti-hypertensive and renal protective effects. Fatty acid metabolism in the kidney is involved in renal damage. In this study, we investigated the effects of the Ex on blood pressure, renal damages, and fatty acid metabolism in Dahl salt-sensitive rats. Design and method: Six-week-old male Dahl salt-sensitive rats were divided into three groups: 1) normal salt diet (NS); 2) high salt diet (HS); 3) HS+Ex. NS or HS groups were fed diet containing 0.6% or 8% NaCl. Treadmill running was performed in HS+Ex group for 8 weeks (5 days/week; 60 min/day at 16–20 m/min, 0% grade). Systolic blood pressure (SBP) was monitored by tail-cuff method. Renal function, histology and the expression of enzymes and regulators for fatty acid metabolism were then assessed. Results: HS significantly elevated SBP, and Ex did not change SBP. HS significantly decreased creatinine clearance, and Ex significantly ameliorated creatinine clearance. HS significantly increased urinary protein excretion, and Ex significantly suppressed urinary protein excretion. HS induced glomerular sclerosis, and Ex suppressed them. HS decreased the renal expression of enzymes for fatty acid β;-oxidation including carnitine palmitoyltransferase type I (CPTI) and very long, medium and short-chain acyl-CoA dehydrogenases (CADs) and their transcription factors; peroxisome proliferator-activated receptor α (PPARα) and PPARγ-coactivator-1α (PGC-1α). Ex increased the renal expression of CPTI, CADs, PPARα and PGC-1α. Conclusions: Ex improves HS-induced renal damage with fatty acid β;-oxidation with increasing PPARα and PGC-1α in Dahl salt-sensitive rats in a systolic blood pressure-independent manner. These results suggest that Ex may have beneficial effects in HS-induced renal damage.

Anti-inflammatory effects of endothelin receptor blockade in left atrial tissue of spontaneously hypertensive rats.

ObjectiveIn spontaneously hypertensive rats (SHR) atrial remodeling has been shown to involve increase in endothelin (ET) signaling. Furthermore, inflammatory processes may further contribute to tissue remodeling. The aimed of this study was to investigate whether an endothelin receptor antagonist, macitentan, could reduce left atrial (LA) remodeling in arterial hypertension.MethodsMolecular characterization of atria was performed in SHR at the age of 8 months and their age-matched normotensive control rats (WKY). SHR were treated with macitentan and, for comparison with a blood pressure reducing drug, with doxazosin. After two months of treatment, molecules involved in endocardial inflammation and atrial calcium handling were assessed. The molecular changes provoked by rapid-pacing (RAP) were analyzed in atrial tissue slices.ResultsDoxazosin reduced the systolic blood pressure compared with the untreated SHR (159 ± 26 vs. 176 ± 17; P < 0.05) or macitentan (vs. 189 ± 21; P < 0.05). Macitentan lowered the increased levels of atrial ET-1 and abrogated the pacing-induced upregulation of preproET-1-mRNA in atrial slices from SHR. Macitentan reduced the elevated levels of atrial 8-isoprostanes, the increased expression of pro-inflammatory ICAM-1 and IL-8, the phosphorylation of MAP kinases, ERK and p38, the phosphorylation of NF-κB and the expression of VCAM-mRNA. Major Ca2+-regulating proteins and markers of hypertrophy and fibrosis, however, were not affected. Doxazosin elicited similar changes, except for the alterations in ET-1 levels, NF-κB phosphorylation and VCAM-mRNA.ConclusionMacitentan reversed pro-inflammatory remodeling in hypertensive atria in a blood pressure-independent manner, which might prevent endocardial dysfunction and thereby, thrombogenesis in arterial hypertension.

Renoprotective Effects of Small Interfering RNA Targeting Liver Angiotensinogen in Experimental Chronic Kidney Disease.

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Activation of G protein-coupled estrogen receptor 1 ameliorates proximal tubular injury and proteinuria in Dahl salt-sensitive female rats.

Recent evidence indicates a crucial role for G protein-coupled estrogen receptor 1 (GPER1) in the maintenance of cardiovascular and kidney health in females. The current study tested whether GPER1 activation ameliorates hypertension and kidney damage in female Dahl salt-sensitive (SS) rats fed a high-salt (HS) diet. Adult female rats were implanted with telemetry transmitters for monitoring blood pressure and osmotic minipumps releasing G1 (selective GPER1 agonist, 400 μg/kg/day ip) or vehicle. Two weeks after pump implantation, rats were shifted from a normal-salt (NS) diet (0.4% NaCl) to a matched HS diet (4.0% NaCl) for 2 wk. Twenty-four hour urine samples were collected during both diet periods and urinary markers of kidney injury were assessed. Histological assessment of kidney injury was conducted after the 2-wk HS diet period. Compared with values during the NS diet, 24-h mean arterial pressure markedly increased in response to HS, reaching similar values in vehicle-treated and G1-treated rats. HS also significantly increased urinary excretion of protein, albumin, nephrin (podocyte damage marker), and KIM-1 (proximal tubule injury marker) in vehicle-treated rats. Importantly, G1 treatment prevented the HS-induced proteinuria, albuminuria, and increase in KIM-1 excretion but not nephrinuria. Histological analysis revealed that HS-induced glomerular damage did not differ between groups. However, G1 treatment preserved proximal tubule brush-border integrity in HS-fed rats. Collectively, our data suggest that GPER1 activation protects against HS-induced proteinuria and albuminuria in female Dahl SS rats by preserving proximal tubule brush-border integrity in a blood pressure-independent manner.

Maxacalcitol (22-Oxacalcitriol (OCT)) Retards Progression of Left Ventricular Hypertrophy with Renal Dysfunction Through Inhibition of Calcineurin-NFAT Activity

Left ventricular hypertrophy (LVH) is a cardiovascular complication highly prevalent in patients with chronic kidney disease (CKD). Previous studies analyzing 1α-hydroxylase or vitamin D receptor (Vdr) knockout mice revealed active vitamin D as a promising agent inhibiting LVH progression. Paricalcitol, an active vitamin D analog, failed to suppress the progression of LV mass index (LVMI) in pre-dialysis patients with CKD. As target genes of activated VDR differ depending on its agonists, we examined the effects of maxacalcitol (22-oxacalcitriol: OCT), a less calcemic active vitamin D analog, on LVH in hemodialysis patients and animal LVH models with renal insufficiency. In retrospective cohort study, patients treated with OCT who underwent hemodialysis were enrolled. Using cardiac echocardiography, LV mass was evaluated by the area-length method. In animal study, angiotensin II (Ang II)-infused Wister rats with heminephrectomy or Ang II-stimulated neonatal rat ventricular myocytes (NRVM) were treated with OCT. OCT significantly inhibited the progression of LVMI in hemodialysis patients. In Ang II-infused heminephrectomized rats, OCT suppressed the progression of LVH in a blood pressure-independent manner. OCT also suppressed the activity of calcineurin in the left ventricle of model rats. Specifically, OCT reduced the protein levels of calcineurin A, but not the mRNA levels of Ppp3ca (calcineurin Aα). Luciferase assays showed that OCT increased the promoter activity of Fbxo32 (atrogin1), an E3 ubiquitin ligase targeting calcineurin A. Finally, OCT promoted ubiquitination and degradation of calcineurin A. Our works indicated that OCT retards progression of LVH through calcineurin-NFAT pathway, which reveal a novel aspect of OCT in attenuating pathological LVH.

From ARB to ARNI in Cardiovascular Control.

Coexistence of hypertension, diabetes mellitus and chronic kidney disease synergistically aggravates the risk of cardiovascular and renal morbidity and mortality. These high-risk, multi-morbid patient populations benefit less from currently available anti-hypertensive treatment. Simultaneous angiotensin II type 1 receptor blockade and neprilysin inhibition (‘ARNI’) with valsartan/sacubitril (LCZ696) might potentiate the beneficial effects of renin-angiotensin-aldosterone inhibition by reinforcing its endogenous counterbalance, the natriuretic peptide system. This review discusses effects obtained with this approach in animals and humans. In animal models of hypertension, either alone or in combination with myocardial infarction or diabetes, ARNI consistently reduced heart weight and cardiac fibrosis in a blood pressure-independent manner. Additionally, LCZ696 treatment reduced proteinuria, focal segmental glomerulosclerosis and retinopathy, thus simultaneously demonstrating favourable effects on microvascular complications. These results were confirmed in patient populations. Besides blood pressure reductions in hypertensive patients and greatly improved (cardiovascular) mortality in heart failure patients, ventricular wall stress and albuminuria were reduced particularly in diabetic patients. The exact underlying mechanism remains unknown, but may involve improved renal haemodynamics and reduced glomerulosclerosis, e.g. related to a rise in natriuretic peptide levels. However, the assays of these peptides are hampered by methodological artefacts. Moreover, since sacubitrilat is largely renally cleared, drug accumulation may occur in patients with impaired renal function and thus hypotension is a potential side effect in patients with chronic kidney disease. Further caution is warranted since neprilysin also degrades endothelin-1 and amyloid beta in animal models. Accumulation of the latter may increase the risk of Alzheimer’s disease.

PP.30.09] DOSE SALT INTAKE PREDICT THE NEW ONSET OF CHRONIC KIDNEY DISEASE?

Objective: Dietary salt, which is one of the most important modifiable factors in our life style, is associated not only with blood pressure but also with several cardiovascular diseases in a blood pressure–independent manner. We investigated if salt intake predicts new onset of chronic kidney disease (CKD) in the general population. Design and method: Consecutive 8,161 participants (male = 5,168, 55.8 ± 11.3 year-old) with normal estimated glomerular filtration rate (eGFR;> = 60 ml/min/1.73 m2) in our physical health check-up program were enrolled in this study. After baseline examination, participants were followed up (median 1,098 day) with the endpoint being the development of CKD (eGFR<60 ml/min/1.73 m2). Individual salt intake was estimated using spot urine by a previously reported method and GFR was estimated using the Japanese Society of Nephrology formula. Results: Salt intake was 8.9 ± 2.0 g/day in male and 8.6 ± 1.9 g/day in female subjects. eGFR was 80.1 ± 12.7 ml/min/1.73 m2 at baseline, and during the follow-up period, CKD developed in 706 subjects (29.9 per 1000 person-year), with the incidence being more frequent in male than female subjects (31.1 vs. 27.8 per 1000 person-year). Non-adjusted hazard ratio (HR) (95% confidence interval [CI]) of salt intake for the new CKD was 1.071 (1.034–1.109). Multivariate Cox-hazard analysis adjusted for body mass index, systolic blood pressure, heart rate, uric acid, fasting plasma glucose, low-density lipoprotein cholesterol, triglyceride, hemoglobin, smoking status and eGFR at baseline demonstrated that salt intake was a significant predictor of new onset CKD (HR = 1.077, 95%CI = 1.037–1.119). Univariate and adjusted multivariate liner regression analyses indicated the significant correlation between salt intake at baseline and yearly changes in eGFR (r = -0.081, p < 0.001 and r = -0.069, p < 0.001, respectively). Similar results were obtained in a sub-analysis performed in subjects with normal blood pressure (n = 5,863). Conclusions: Dietary salt intake is significantly associated with the development of CKD and decrease in eGFR in the general population, even in normotensive subjects. These results suggest that salt restriction is beneficial for the prevention of the impairment of kidney function and the development of CKD.

The role of fibroblast growth factor 23 and Klotho in uremic cardiomyopathy.

In chronic kidney disease (CKD), multiple factors contribute to the development of cardiac hypertrophy by directly targeting the heart or indirectly by inducing systemic changes such as hypertension, anemia, and inflammation. Furthermore, disturbances in phosphate metabolism have been identified as nonclassical risk factors for cardiovascular mortality in these patients. With declining kidney function, the physiologic regulators of phosphate homeostasis undergo changes in their activity as well as their circulating levels, thus potentially contributing to cardiac hypertrophy once they are out of balance. Recently, two of these phosphate regulators, fibroblast growth factor 23 (FGF23) and Klotho, have been shown to affect cardiac remodeling, thereby unveiling a novel pathomechanism of cardiac hypertrophy in CKD. Here we discuss the potential direct versus indirect effects of FGF23 and the soluble form of Klotho on the heart, and their crosstalk in the regulation of cardiac hypertrophy. In models of CKD, FGF23 can directly target cardiac myocytes via FGF receptor 4 and induce cardiac hypertrophy in a blood pressure-independent manner. Soluble Klotho may directly target the heart via an unknown receptor thereby protecting the myocardium from pathologic stress stimuli that are associated with CKD, such as uremic toxins or FGF23. Elevated serum levels of FGF23 and reduced serum levels of soluble Klotho contribute to uremic cardiomyopathy in a synergistic manner.

Activation of the Renin-Angiotensin System Promotes Colitis Development.

The renin-angiotensin system (RAS) plays pathogenic roles in renal and cardiovascular disorders, but whether it is involved in colitis is unclear. Here we show that RenTgMK mice that overexpress active renin from the liver developed more severe colitis than wild-type controls. More than 50% RenTgMK mice died whereas all wild-type mice recovered. RenTgMK mice exhibited more robust mucosal TH17 and TH1/TH17 responses and more profound colonic epithelial cell apoptosis compared to wild-type controls. Treatment with aliskiren (a renin inhibitor), but not hydralazine (a smooth muscle relaxant), ameliorated colitis in RenTgMK mice, although both drugs normalized blood pressure. Chronic infusion of angiotensin II into wild-type mice mimicked the severe colitic phenotype of RenTgMK mice, and treatment with losartan [an angiotensin type 1 receptor blocker (ARB)] ameliorated colitis in wild-type mice, confirming a colitogenic role for the endogenous RAS. In human biopsies, pro-inflammatory cytokines were suppressed in patients with inflammatory bowel disease who were on ARB therapy compared to patients not receiving ARB therapy. These observations demonstrate that activation of the RAS promotes colitis in a blood pressure independent manner. Angiotensin II appears to drive colonic mucosal inflammation by promoting intestinal epithelial cell apoptosis and mucosal TH17 responses in colitis development.

Effects of omega-3 fatty acids on arterial stiffness in patients with hypertension: a randomized pilot study

BackgroundOmega–3 fatty acids prevent cardiovascular disease (CVD) events in patients with myocardial infarction or heart failure. Benefits in patients without overt CVD have not been demonstrated, though most studies did not use treatment doses (3.36 g) of omega-3 fatty acids. Arterial stiffness measured by pulse wave velocity (PWV) predicts CVD events independent of standard risk factors. However, no therapy has been shown to reduce PWV in a blood pressure-independent manner. We assessed the effects of esterified omega–3 fatty acids on PWV and serum markers of inflammation among patients with hypertension.Design and methodsWe performed a prospective, randomized; double-blinded pilot study of omega-3 fatty acids among 62 patients in an urban, safety net hospital. Patients received 3.36 g of omega–3 fatty acids vs. matched placebo daily for 3-months. The principal outcome measure was change in brachial-ankle PWV. Serum inflammatory markers associated with CVD risk were also assessed.ResultsThe majority (71 %) were of Latino ethnicity. After 3-months, mean change in arterial PWV among omega-3 and placebo groups was −97 cm/s vs. −33 cm/s respectively (p = 0.36 for difference, after multivariate adjustment for baseline age, systolic blood pressure, and serum adiponectin). Non-significant reductions in lipoprotein-associated phospholipase A2 (LpPLA2) mass and high sensitivity C-reactive protein (hsCRP) relative to placebo were also observed (p = 0.08, and 0.21, respectively).ConclusionHigh-dose omega-3 fatty acids did not reduce arterial PWV or markers of inflammation among patients within a Latino-predominant population with hypertension.Clinical trial registrationNCT00935766, registered July 8 2009.

Soluble guanylate cyclase stimulator BAY 41-8543 and female sex ameliorate uremic aortic remodeling in a rat model of mild uremia.

Cardiovascular disease is the leading comorbidity in renal patients and has been related to impaired nitric oxide signaling. Estrogens exert protective effects on the vascular system. This study investigates the effects of biological sex and nitric oxide-independent soluble guanylate cyclase (sGC) stimulator BAY 41-8543 on aortic remodeling in experimental mild uremia. Age-matched male and female Wistar rats were assigned for 18 weeks into sham-operated, subtotally nephrectomized (SNX), SNX + BAY 41-8543 and SNX + hydralazine. Analysis involved functional, histological, and molecular kidney and thoracic aorta parameters. SNX significantly increased SBP, which was comparably reduced to control levels by BAY 41-8543 and hydralazine. In SNX males, uremic aortic remodeling was characterized by marked media thickening and increased media-to-lumen ratio (P < 0.01), vascular smooth muscle cell (VSMC) proliferation, macrophage infiltration, extracellular matrix turnover, decreased aortic elastin-to-collagen ratio (P < 0.01) and endothelial nitric oxide-synthase (eNOS) mRNA expression (P < 0.05). No significant alterations of aortic media-to-lumen ratio, VSMC proliferation, macrophage infiltration, matrix metalloproteinase-2, and eNOS mRNA expressions were seen in female uremic animals. BAY 41-8543 significantly ameliorated uremic aortic remodeling and stiffening involving reduced VSMC proliferation, collagen I-deposition, extracellular matrix turnover, and increased elastin content and eNOS mRNA expression. Hydralazine treatment did not substantially alter aortic remodeling. Experimental mild uremia leads to pronounced aortic hypertrophic remodeling and stiffening with sex-dependent alternations, and these are more severe in male rats. BAY 41-8543 ameliorates uremic aortic remodeling in a blood pressure-independent manner. The results suggest that sGC-stimulators may offer a novel treatment mode for pathological arterial wall remodeling in patients with impaired renal function.

CXCR4 Antagonism Attenuates the Development of Diabetic Cardiac Fibrosis.

Heart failure (HF) is an increasingly recognized complication of diabetes. Cardiac fibrosis is an important causative mechanism of HF associated with diabetes. Recent data indicate that inflammation may be particularly important in the pathogenesis of cardiovascular fibrosis. We sought to determine the mechanism by which cardiac fibrosis develops and to specifically investigate the role of the CXCR4 axis in this process. Animals with type I diabetes (streptozotocin treated mice) or type II diabetes (Israeli Sand-rats) and controls were randomized to treatment with a CXCR4 antagonist, candesartan or vehicle control. Additional groups of mice also underwent bone marrow transplantation (GFP+ donor marrow) to investigate the potential role of bone marrow derived cell mobilization in the pathogenesis of cardiac fibrosis. Both type I and II models of diabetes were accompanied by the development of significant cardiac fibrosis. CXCR4 antagonism markedly reduced cardiac fibrosis in both models of diabetes, similar in magnitude to that seen with candesartan. In contrast to candesartan, the anti-fibrotic actions of CXCR4 antagonism occurred in a blood pressure independent manner. Whilst the induction of diabetes did not increase the overall myocardial burden of GFP+ cells, it was accompanied by an increase in GFP+ cells expressing the fibroblast marker alpha-smooth muscle actin and this was attenuated by CXCR4 antagonism. CXCR4 antagonism was also accompanied by increased levels of circulating regulatory T cells. Taken together the current data indicate that pharmacological inhibition of CXCR4 significantly reduces diabetes induced cardiac fibrosis, providing a potentially important therapeutic approach.

Renoprotective Effects of Direct Renin Inhibition in Glomerulonephritis

The development of glomerulonephritis causes glomerular injury and renal dysfunction and is thought to increase renin release, thus activating the renin-angiotensin system (RAS). The aims of this study were to demonstrate activation of the intrarenal RAs and determine the effects of direct renin inhibition (DRi) on the progression of glomerulonephritis. Rats were treated with anti-Thy1.1 antibody with or without DRI, aliskiren (30 mg/kg/d). In the glomerulonephritic rats, protein, microalbumin excretion levels, urinary angiotensinogen excretion, glomerular expansion score and intrarenal transforming growth factor-β and plasminogen activator inhibitor-1 mRNA levels were augmented compared with control rats; however, hypertension was not observed in the glomerulonephritic rats, and aliskiren treatment did not modify their blood pressure. The increases in urinary protein (94.7 ± 13.0 mg/d) and microalbumin (7.52 ± 2.6 mg/d) excretion were reduced by aliskiren (43.6 ± 4.5 mg/d of protein and 2.57 ± 0.7 mg/d of microalbumin). Furthermore, the progression of glomerular expansion and elevation of intrarenal transforming growth factor-β and plasminogen activator inhibitor-1 levels were prevented by aliskiren. Importantly, aliskiren suppressed the augmentation of urinary angiotensinogen levels, the increased angiotensinogen expression in the kidneys and the increases in Ang II levels in renal medulla induced by the anti-Thy1.1 antibody. These results suggest that DRI with aliskiren prevents intrarenal RAS activation leading to mitigation of the development of glomerulonephritis. In addition, the renoprotective effects of DRI on glomerulonephritis occur in a blood pressure-independent manner. Accordingly, treatment with aliskiren may be an effective approach to treat glomerulonephritis and other intrarenal RAS-associated kidney diseases.

Abstract 659: Curcumin Ameliorates Cardiac Dysfunction in the Ovariectomized Diabetic mRen2.Lewis Rat by Inhibiting Renin Angiotensin System

Diabetes is a well-recognized independent risk factor for the development of cardiovascular disease in women. Moreover, hypertension and loss of estrogen are additional complicating factors to diabetic heart disease. Curcumin, an active compound in the widely used spice turmeric, exerts therapeutic potential in diabetes mellitus; however, the underlying mechanisms are not fully understood. The present study was designed to investigate the potential of curcumin to ameliorate early cardiac dysfunction in insulin- and estrogen-depleted hypertensive mRen2.Lewis rats by altering the renin angiotensin system as one of the major contributors to the development of diabetic cardiomyopathy. Ovariectomy (OVX) was performed at 10 weeks of age and diabetes (D) subsequently induced at 11 weeks with streptozotocin (65 mg/kg). Only animals that showed hyperglycemia greater than 200 mg/dl were considered diabetic. OVX-D rats were given curcumin at a dose of 200 mg/kg/day (OVX-D &amp; CUR; n=7) or vehicle (OVX-D &amp; VEH; n=8) by gastric gavage starting two days after streptozotocin injection. Intact non-diabetic mRen2.Lewis rats served as controls (C; n=9). After four weeks, concomitant insulin and estrogen depletion induced systolic and diastolic dysfunction, indicated by decreased fractional shortening (FS; C: 60.0 ± 1.5 vs OVX-D &amp; VEH: 43.7 ± 2.2 %; p&lt;0.05) and Tissue Doppler velocity at the level of mitral annulus (e’; C: 75.0 ± 3.4 vs OVX-D &amp; VEH: 58.6 ± 5.6 mm/s; p&lt;0.05) that was associated with increased blood pressure (BP; C: 131 ± 3 vs 179 ± 2 mmHg; p&lt;0.05), elevated plasma angiotensin II (Ang II; C: 20 ± 4 vs 32 ± 2 pg/ml; p&lt;0.05), and cardiac expression of Ang II type 1 receptor (AT1; C: 100 ± 12 vs 206 ± 33 %; p&lt;0.05). Curcumin treatment did not affect BP (164 ± 6 mmHg; p&gt;0.05) but attenuated cardiac systolic (FS: 53 ± 3%, p&lt;0.05) and diastolic dysfunction (e’: 74 ± 3 mm/s; p&lt;0.05) while reducing AT1 expression (120 ± 12 %; p&lt;0.05) in the diabetic heart. It also decreased plasma Ang II to the levels not different from the controls (21.6 ± 3 pg/ml; p&gt;0.05). In conclusion, the present study suggests that curcumin treatment, in a blood pressure independent manner, may ameliorate early cardiac dysfunction in estrogen- and insulin-depleted mRen2.Lewis rats by reducing Ang II signaling pathway.

Abstract 456: Role of Signal Transducer and Activator of Transcription protein (STAT)-1 in the Angiotensin II-induced Cardiovascular Damage

Background: Inflammation participates importantly in hypertensive organ damage. Angiotensin II (Ang II) plays a crucial role in hypertension and induces inflammation. An essential mediator of inflammation is the transcription factor STAT1 which is activated by interferon but also by Ang II. We hypothesized that activation of STAT1 during Ang II infusion upregulates chemokines, enhances chemotaxis and consequently results in heart fibrosis and vessel dysfunction independent on blood pressure and hypertrophy Methods: C57BL/6, C57BL/6 receiving candesartan (5mg/kg) and STAT1-/- mice received infusion of Ang II 1.5 μg/g/day or placebo for 4 weeks (n=9/group). Blood pressure was measured using tail cuff pletysmography. Expression of chemokines Cxcl10, Cxcl9 and MCP-1 as well as Nos2 were investigated. Small mesenteric arteries (SMA) were mounted in a wire myograph to assess their function. Cardiac hypertrophy and inflammation (CD45 staining) and fibrosis (hydroxyproline assay) were determined. Results: Ang II caused expression of IFNg in C57BL/6 and STAT1-/- in vitro and in vivo. Blood pressure and cardiac hypertrophy did not differ between angiotensin treated C57BL/6 and STAT1-/- mice. Ang II increased in C57BL/6 expression of STAT1 dependent genes of chemokines and Nos2 (Cxcl10: 4.8-fold, Cxcl9: 3.4-fold, MCP-1: 6.6-fold, Nos2: 2.6-fold; all P&lt;0.05) whereas this remained abolished in STAT1-/- mice. Ang II lead in STAT1-/- mice as compared to C57BL/6 to decreased cardiac CD45 number/view (C57BL/6-AngII: 27±4 STAT1-/--AngII: 11±5; P&lt;0.05) and reduced cardiac fibrosis (hydroxyproline assay: C57BL/6-AngII: 80.6±11.8μmol/l versus STAT1-/- -AngII: 55.0±8.4μmol/l; P&lt;0.05). Mesenteric arteries of STAT1-/- mice were fully protected against angiotensin induced endothelial dysfunction. Candesartan (AT1 receptor antagonist) inhibited action of Ang II in C57BL/6 and reduced but not reversed expression of chemokines in the heart. Conclusions: Lack of STAT1 revealed protection against Ang II-induced cardiac fibrosis and endothelial dysfunction. We suggest that STAT1-induced chemokine activation induces chemotaxis into hypertensive target organs and modifies cardiac fibrosis and vascular dysfunction in a blood pressure-independent manner.

Valsartan regulates myocardial autophagy and mitochondrial turnover in experimental hypertension.

Renovascular hypertension alters cardiac structure and function. Autophagy is activated during left ventricular hypertrophy and linked to adverse cardiac function. The angiotensin II receptor blocker, valsartan, lowers blood pressure and is cardioprotective, but whether it modulates autophagy in the myocardium is unclear. We hypothesized that valsartan would alleviate autophagy and improve left ventricular myocardial mitochondrial turnover in swine renovascular hypertension. Domestic pigs were randomized to control, unilateral renovascular hypertension, and renovascular hypertension treated with valsartan (320 mg/d) or conventional triple therapy (reserpine+hydralazine+hydrochlorothiazide) for 4 weeks after 6 weeks of renovascular hypertension (n=7 each group). Left ventricular remodeling, function, and myocardial oxygenation and microcirculation were assessed by multidetector computer tomography, blood oxygen level-dependent MRI, and microcomputer tomography. Myocardial autophagy, markers for mitochondrial degradation and biogenesis, and mitochondrial respiratory-chain proteins were examined ex vivo. Renovascular hypertension induced left ventricular hypertrophy and myocardial hypoxia, enhanced cellular autophagy and mitochondrial degradation, and suppressed mitochondrial biogenesis. Valsartan and triple therapy similarly decreased blood pressure, but valsartan solely alleviated left ventricular hypertrophy, ameliorated myocardial autophagy and mitophagy, and increased mitochondrial biogenesis. In contrast, triple therapy only slightly attenuated autophagy and preserved mitochondrial proteins, but elicited no improvement in mitophagy. These data suggest a novel potential role of valsartan in modulating myocardial autophagy and mitochondrial turnover in renovascular hypertension-induced hypertensive heart disease, which may possibly bolster cardiac repair via a blood pressure-independent manner.

Late dual endothelin receptor blockade with bosentan restores impaired cerebrovascular function in diabetes

AimsUp-regulation of the endothelin (ET) system in type-2 diabetes increases contraction and decreases relaxation in basilar artery. We showed that 1) ET-receptor antagonism prevents diabetes-mediated cerebrovascular dysfunction; and 2) glycemic control prevents activation of the ET-system in diabetes. Here, our goal is to determine whether and to what extent glycemic control or ET-receptor antagonism reverses established cerebrovascular dysfunction in diabetes. Main methodsNon-obese type-2 diabetic Goto–Kakizaki rats were administered either vehicle, metformin (300mg/kg/day) or dual ET-receptor antagonist bosentan (100mg/kg) for 4-weeks starting at 18-weeks after established cerebrovascular dysfunction (n=5–6/group). Control group included vehicle-treated aged-matched Wistar rats. Blood glucose and pressure were monitored weekly. At termination, basilar arteries were collected and cumulative dose–response curves to ET-1 (0.1–500nM), 5-HT (1–1000nM) and acetylcholine (Ach, 0.1nM–5μM) were studied by wire myograph. Middle cerebral artery (MCA) myogenic reactivity and tone were measured using pressurized arteriograph. Key findingsThere was no difference in ET-1 and 5-HT-mediated constrictions. Endothelium-dependent relaxation was impaired in diabetes. Bosentan improved sensitivity to Ach as well as the maximum relaxation. Myogenic-tone is decreased over the course of the disease. Both treatments improved the ability of MCAs to develop tone at 80mmHg and only bosentan improved the tone at higher pressures. SignificanceThese results suggest that contractile response is not affected by glycemic control or ET-receptor antagonism. Meanwhile, dual ET-receptor blockade is effective in partially improving endothelium-dependent relaxation and myogenic response in a blood pressure-independent manner even after established cerebrovascular dysfunction and offers therapeutic potential.

Sympathoinhibitory Effect of Diltiazem and Prevention of Aneurysm Formation

We read with great interest the article by Mieth and colleagues1 dealing with the effect of the benzothiazepine-type calcium channel blocker, diltiazem, on aortic aneurysm formation in a mouse model. The results of their study demonstrated that diltiazem significantly prevented abdominal aneurysm formation in a blood pressure–independent manner in male apolipoprotein E–deficient mice infused with angiotensin II. In addition, the authors showed that diltiazem inhibited the interleukin-6 (IL-6)–induced mRNA expression of IL-1β and the monocyte chemoattractant protein …

Triptolide protects rat heart against pressure overload-induced cardiac fibrosis

Emerging evidence underlines the role of inflammation activation in the process of cardiac fibrosis. Triptolide has potent anti-inflammatory and anti-proliferative properties, and extensively used in the treatment of chronic inflammatory disorders. In the current study, we test the hypothesis that triptolide treatment facilitates to attenuate chronic pressure overload-induced cardiac fibrosis in a model of rat. Adult male Sprague-Dawley rats were subjected to a suprarenal abdominal aorta constriction (AC) or sham (as control) to induce sustained pressure overload. Eight weeks later, rats were randomly assigned to receive triptolide (9 μg/kg.d, i.p) or vehicle (0.1% dimethyl sulfoxide, 0.2 ml/d, i.p) treatment for an additional 8 weeks. AC caused significant pathological hypertrophy, cardiac fibrosis and reduced cardiac diastolic function. Triptolide treatment markedly inhibited AC-induced increases in myocardial collagen volume fraction, collagen type I/III deposition, left ventricular end-diastolic pressure, expressions of pro-fibrogenic factors (transforming growth factor-β and angiotensin II) and pro-inflammatory cytokines (IL-1β and IL-6), NF-κB activation and inflammatory cell infiltration in left ventricles compared with vehicle, without affecting cardiac hypertrophy. However, triptolide had no effects on systemic blood pressure and circulating angiotensin II level. Collectively, the findings suggested that triptolide treatment elicits favorable anti-fibrogenic effect in a blood pressure-independent manner, at least in part, through inhibiting myocardial pro-fibrogenic factor production and inflammatory activation in the pressure overloaded heart.