Hypertensive Heart Failure Rats Research Articles

The redox-active defensive Selenoprotein T as a novel stress sensor protein playing a key role in the pathophysiology of heart failure

Maladaptive cardiac hypertrophy contributes to the development of heart failure (HF). The oxidoreductase Selenoprotein T (SELENOT) emerged as a key regulator during rat cardiogenesis and acute cardiac protection. However, its action in chronic settings of cardiac dysfunction is not understood. Here, we investigated the role of SELENOT in the pathophysiology of HF: (i) by designing a small peptide (PSELT), recapitulating SELENOT activity via the redox site, and assessed its beneficial action in a preclinical model of HF [aged spontaneously hypertensive heart failure (SHHF) rats] and against isoproterenol (ISO)-induced hypertrophy in rat ventricular H9c2 and adult human AC16 cardiomyocytes; (ii) by evaluating the SELENOT intra-cardiomyocyte production and secretion under hypertrophied stimulation. Results showed that PSELT attenuated systemic inflammation, lipopolysaccharide (LPS)-induced macrophage M1 polarization, myocardial injury, and the severe ultrastructural alterations, while counteracting key mediators of cardiac fibrosis, aging, and DNA damage and restoring desmin downregulation and SELENOT upregulation in the failing hearts. In the hemodynamic assessment, PSELT improved the contractile impairment at baseline and following ischemia/reperfusion injury, and reduced infarct size in normal and failing hearts. At cellular level, PSELT counteracted ISO-mediated hypertrophy and ultrastructural alterations through its redox motif, while mitigating ISO-triggered SELENOT intracellular production and secretion, a phenomenon that presumably reflects the extent of cell damage. Altogether, these results indicate that SELENOT could represent a novel sensor of hypertrophied cardiomyocytes and a potential PSELT-based new therapeutic approach in myocardial hypertrophy and HF.Graphical

Analysis of the gut microbiota profile targeted to multiple hypervariable regions of 16S rRNA in a hypertensive heart failure rat model.

The gut microbiota, comprising a diverse community of microorganisms, significantly influences various aspects of health. Changes in the composition of the gut microbiota are implicated in adverse effects on host physiology, contributing to the pathogenesis of cardiovascular diseases, among others pathological conditions. Understanding the role of the gut microbiota in the context of heart failure is particularly important. In this regard, the spontaneously hypertensive heart failure (SHHF) rat is an adequate experimental model since exhibits many features in common with heart failure (HF) in humans. Recent advancements in next-generation sequencing (NGS) have greatly improved microbiome analysis. However, standardization and the adoption of best practices are essential to mitigate experimental variations across studies. This manuscript outlines a straightforward methodology for analyzing gut microbiota composition in SHHF rat fecal samples using 16S rRNA sequencing, emphasizing the relevance of gut microbiota in heart failure.

VEGF-B hypertrophy predisposes to transition from diastolic to systolic heart failure in hypertensive rats.

Cardiac energy metabolism is centrally involved in heart failure (HF), although the direction of the metabolic alterations is complex and likely dependent on the particular stage of HF progression. Vascular endothelial growth factor B (VEGF-B) has been shown to modulate metabolic processes and to induce physiological cardiac hypertrophy; thus, it could be cardioprotective in the failing myocardium. This study investigates the role of VEGF-B in cardiac proteomic and metabolic adaptation in HF during aldosterone and high-salt hypertensive challenges. Male rats overexpressing the cardiac-specific VEGF-B transgene (VEGF-B TG) were treated for 3 or 6 weeks with deoxycorticosterone-acetate combined with a high-salt (HS) diet (DOCA + HS) to induce hypertension and cardiac damage. Extensive longitudinal echocardiographic studies of HF progression were conducted, starting at baseline. Sham-treated rats served as controls. To evaluate the metabolic alterations associated with HF, cardiac proteomics by mass spectrometry was performed. Hypertrophic non-treated VEGF-B TG hearts demonstrated high oxygen and adenosine triphosphate (ATP) demand with early onset of diastolic dysfunction. Administration of DOCA + HS to VEGF-B TG rats for 6 weeks amplified the progression from cardiac hypertrophy to HF, with a drastic drop in heart ATP concentration. Dobutamine stress echocardiographic analyses uncovered a significantly impaired systolic reserve. Mechanistically, the hallmark of the failing TG heart was an abnormal energy metabolism with decreased mitochondrial ATP, preceding the attenuated cardiac performance and leading to systolic HF. This study shows that the VEGF-B TG accelerates metabolic maladaptation which precedes structural cardiomyopathy in experimental hypertension and ultimately leads to systolic HF.

The Protective Role of the Long Pentraxin PTX3 in Spontaneously Hypertensive Rats with Heart Failure.

Pentraxin 3 (PTX3) is synthesized locally and released into the circulation, reflecting local inflammation in the cardiovascular system. Therefore, we conducted a study to explore the effect of PTX3 in spontaneously hypertensive heart failure (SHHF) rats. Sprague Dawley (SD) and SHHF rats were treated with recombinant PTX3 protein, and the blood pressure (BP) and echocardiographic parameters were collected. Radioimmunoassay, enzyme immunoassay and enzyme-linked immunosorbent assay (ELISA) were applied to detect plasma levels of atrial/B-type natriuretic peptide (ANP/BNP) and PTX3. The pathological changes in the myocardial tissues were observed by hematoxylin and eosin (HE) and Masson stainings. The mRNA and protein expressions were detected by quantitative real-time reverse-transcription polymerase chain reaction (qPCR) and western blotting. Cardiomyocyte apoptosis was evaluated by TUNEL staining and DNA fragmentation test. Increased plasma concentrations of PTX3 were found in SHHF rats compared with SD rats, which was further enhanced by recombinant PTX3 protein. After injection with recombinant PTX3 protein, the heart function was improved in SHHF rats with the decreased systolic and diastolic BP, and the reduced plasma levels of ANP and BNP. Moreover, PTX3 improved the myocardial damage and interstitial fibrosis in SHHF rats with reduced cardiomyocyte apoptosis and decreased mRNA expressions of pro-inflammatory factors in myocardial tissues. PTX3 could decrease the BP and plasma levels of ANP and BNP in SHHF rats, as well as improve the inflammation, cardiomyocyte apoptosis, and pathological changes of myocardial tissues, suggesting it may be a useful intervention in the treatment of SHHF.

Changes of gut microbiome composition and metabolites associated with hypertensive heart failure rats

BackgroundThe potential role of the gut microbiome (GM) in heart failure (HF) had recently been revealed. However, the underlying mechanisms of the GM and fecal metabolome in HF have not been characterized. The Dahl salt-sensitive rat model of hypertensive heart failure (H-HF) was used to study the clinical symptoms and characteristics. To elucidate the pathogenesis of HF, we combined 16S rRNA gene sequencing and metabolomics to analyze gut microbial compositions and fecal metabolomic profiles of rats with H-HF.ResultsPCoA of beta diversity shown that the gut microbiome composition profiles among the three groups were separated. Gut microbial composition was significantly altered in H-HF rats, the ratio of Firmicutes to Bacteroidetes(F/B) increased and the abundance of Muribaculaceae, Lachnospiraceae, and Lactobacillaceae decreased. Significantly altered levels of 17 genera and 35 metabolites were identified as the potential biomarker of H-HF. Correlation analysis revealed that specific altered genera were strongly correlated with changed fecal metabolites. The reduction in short-chain fatty acids (SCFA)-producing bacteria and trimethylamine N-oxide (TMAO) might be a notable characteristic for H-HF.ConclusionsThis is the first study to characterize the fecal microbiome of hypertensive heart failure by integrating 16S rRNA gene sequencing and LC–MS-based metabolomics approaches. Collectively, the results suggesting changes of gut microbiome composition and metabolites are associated with hypertensive heart failure rats.

Long‐Term Dipeptidyl Peptidase 4 Inhibition Worsens Hypertension and Renal and Cardiac Abnormalities in Obese Spontaneously Hypertensive Heart Failure Rats

BackgroundThe long‐term effects of dipeptidyl peptidase 4 (DPP4) inhibitors on blood pressure and cardiovascular and renal health remain controversial. Herein, we investigated the extended (>182 days) effects of DPP4 inhibition in a model of spontaneous hypertension, heart failure, diabetes mellitus, obesity and hyperlipidemia.Methods and ResultsAdult obese spontaneously hypertensive heart failure rats (SHHF) were implanted with radio transmitters for measurement of arterial blood pressures. Two weeks later, SHHF were randomized to receive either a DPP4 inhibitor (sitagliptin, 80 mg/kg per day in drinking water) or placebo. At the end of the radiotelemetry measurements, renal and cardiac function and histology, as well as other relevant biochemical parameters, were assessed. For the first 25 days, mean arterial blood pressures were similar in sitagliptin‐treated versus control SHHF; afterwards, mean arterial blood pressures increased more in sitagliptin‐treated SHHF (P<0.000001). The time‐averaged mean arterial blood pressures from day 26 through 182 were 7.2 mm Hg higher in sitagliptin‐treated SHHF. Similar changes were observed for systolic (8.6 mm Hg) and diastolic (6.1 mm Hg) blood pressures, and sitagliptin augmented hypertension throughout the light‐dark cycle. Long‐term sitagliptin treatment also increased kidney weights, renal vascular resistances, the excretion of kidney injury molecule‐1 (indicates injury to proximal tubules), renal interstitial fibrosis, glomerulosclerosis, renal vascular hypertrophy, left ventricular dysfunction, right ventricular degeneration, and the ratios of collagen IV/collagen III and collagen IV/laminin in the right ventricle.ConclusionsThese findings indicate that, in some genetic backgrounds, long‐term DPP4 inhibitor treatment is harmful and identify an animal model to study mechanisms of, and test ways to prevent, DPP4 inhibitor–induced pathological conditions.

Effects of empagliflozin and target-organ damage in a novel rodent model of heart failure induced by combined hypertension and diabetes

Type 2 diabetes mellitus and hypertension are two major risk factors leading to heart failure and cardiovascular damage. Lowering blood sugar by the sodium-glucose co-transporter 2 inhibitor empagliflozin provides cardiac protection. We established a new rat model that develops both inducible diabetes and genetic hypertension and investigated the effect of empagliflozin treatment to test the hypothesis if empagliflozin will be protective in a heart failure model which is not based on a primary vascular event. The transgenic Tet29 rat model for inducible diabetes was crossed with the mRen27 hypertensive rat to create a novel model for heart failure with two stressors. The diabetic, hypertensive heart failure rat (mRen27/tetO-shIR) were treated with empagliflozin (10 mg/kg/d) or vehicle for 4 weeks. Cardiovascular alterations were monitored by advanced speckle tracking echocardiography, gene expression analysis and immunohistological staining. The novel model with increased blood pressure und higher blood sugar levels had a reduced survival compared to controls. The rats develop heart failure with reduced ejection fraction. Empagliflozin lowered blood sugar levels compared to vehicle treated animals (182.3 ± 10.4 mg/dl vs. 359.4 ± 35.8 mg/dl) but not blood pressure (135.7 ± 10.3 mmHg vs. 128.2 ± 3.8 mmHg). The cardiac function was improved in all three global strains (global longitudinal strain − 8.5 ± 0.5% vs. − 5.5 ± 0.6%, global radial strain 20.4 ± 2.7% vs. 8.8 ± 1.1%, global circumferential strain − 11.0 ± 0.7% vs. − 7.6 ± 0.8%) and by increased ejection fraction (42.8 ± 4.0% vs. 28.2 ± 3.0%). In addition, infiltration of macrophages was decreased by treatment (22.4 ± 1.7 vs. 32.3 ± 2.3 per field of view), despite mortality was not improved. Empagliflozin showed beneficial effects on cardiovascular dysfunction. In this novel rat model of combined hypertension and diabetes, the improvement in systolic and diastolic function was not secondary to a reduction in left ventricular mass or through modulation of the afterload, since blood pressure was not changed. The mRen27/tetO-shIR strain should provide utility in separating blood sugar from blood pressure-related treatment effects.

Beneficial Effect of TMAO in Spontaneously Hypertensive Heart Failure Rats is Associated with Diuretic and Hypotensive Actions.

There is an ongoing debate weather trimethylamine‐oxide (TMAO), a molecule present in seafood and a derivate of microbiota metabolism, is beneficial or harmful for the circulatory system. Numerous biophysical studies show that TMAO protects proteins exposed to osmotic and hydrostatic stress (HS). We hypothesized that TMAO may benefit the circulatory system by protecting cardiac proteins exposed to HS produced by the contracting heart.Male, 6‐week‐old, Sprague‐Dawley (SD, n=40) and Spontaneously‐Hypertensive‐Heart‐Failure (SHHF, n=18) rats were randomly divided into either control (Water) or TMAO treatment. After 50 weeks, half of SD were given Isoprenaline (s.c.) to increase arterial blood pressure (BP) and produce a mild, Takotsubo‐like cardiomyopathy (ISO). In vitro, cardiac lactic dehydrogenase (LDH) with or without TMAO was exposed to HS (changes in hydrostatic pressure similar, and higher than those present in the heart) for up to 24hrs and was evaluated using fluorescence correlation spectroscopy.After 58 weeks of the treatment survival was 100% in SD‐Water, SD‐TMAO, ISO‐TMAO and 90% in ISO‐WATER. In SHHF‐Water survival was 66% vs 100% in SHHF‐TMAO (p=0.065). In general, TMAO‐treated rats showed higher natriuresis and diuresis. In comparison to SHHF‐Water, SHHF‐TMAO showed significantly lower plasma NT‐proBNP, lower diastolic BP, lower liver angiotensinogen expression and a trend towards lower cardiac fibrosis. In vitro, exposure of LDH to HS with or without TMAO did not affect the protein structure. TMAO does not exert negative effects. In contrast, TMAO reduces mortality in HF rats that is associated with natriuretic, diuretic and hypotensive effects. HS produced by the contracting heart is neutral for cardiac LDH protein structure.Support or Funding InformationSupported by National Science Centre, Poland grant no 2018/31/B/NZ5/00038.

Abstract P3021: Trimethylamine but Not Trimethylamine N-Oxide Increases Blood Pressure in Rats, Affects Viability of Vascular Smooth Muscle Cells and Degrades Protein Structure

Increased plasma level of trimethylamine N-oxide (TMAO), a liver metabolite of gut bacteria-produced trimethylamine (TMA), has been suggested to increase cardiovascular risk. Mechanisms of TMAO increase in plasma and biological effects of TMAO are obscure. We evaluated the impact of heart failure (HF) on plasma levels of TMA and TMAO, and biological effects of the molecules. Gut permeability was evaluated in male, 58-week-old Spontaneously Hypertensive Heart Failure (SHHF) and Wistar-Kyoto (WKY) rats. TMA and TMAO levels were assessed using LC-MS. Mean arterial blood pressure (MABP) was measured in anaesthetized, male, 16-week-old WKY treated intravenously with either 0.9% NaCl (vehicle), TMA or TMAO. The cytotoxicity of TMA and TMAO in human vascular smooth muscle cells (hVSMCs) was evaluated using MTT assay. The effect of TMA and TMAO on protein structure of bovine albumin was assessed by fluorescence correlation spectroscopy. WKY showed no pathological changes in the circulatory system. SHHF showed HF with reduced ejection fraction. In comparison to WKY, SHHF had a significantly higher plasma level (μM) of TMA (99.05±6.40 vs 149.30±21.87) and TMAO (5.22±0.61 vs 6.69±0.67). SHHF had a significantly higher plasma-to-stool ratio of TMA, decreased intestinal blood flow and morphological alterations in the colon indicating the increased gut-to-blood penetration of TMA due to HF-induced leaky gut. In WKY treatment with the vehicle and TMAO did not affect MABP. In contrast, TMA (at equimolar doses to TMAO) significantly increased MABP by 5-40 mmHg in a dose dependent manner. In vitro, TMA at a concentration of 500μM reduced hVSMCs viability. TMAO at a concentration of 100mM was not cytotoxic whereas TMA at the same concentration killed cells within 24h. Finally, the incubation of albumin with TMA but not with TMAO resulted in the degradation of the protein structure. In conclusion, HF rats show increased plasma TMA and TMAO, which results from increased gut-to-blood penetration of TMA, a TMAO precursor. TMA but not TMAO affects hemodynamics in rats, reduces viability of cells and degrades protein structure. Therefore, TMA but not TMAO may exert deleterious effects on the circulatory system. Further clinical studies should evaluate not only TMAO but also TMA.

Guizhi Decoction () Inhibits Cholinergic Transdifferentiation by Regulating Imbalance of NGF and LIF in Salt-Sensitive Hypertensive Heart Failure Rats.

To observe the imbalance of anatomical and functional innervation factors of sympathetic nerves, nerve growth factor (NGF) and leukemia inhibitory factor (LIF), in salt-sensitive hypertensive heart failure rats and to explore the effects of treatment with Guizhi Decoction () on sympathetic remodeling by inhibiting cholinergic transdifferentiation. SS-13BN and Dahl salt-sensitive (DS) rats were divided into 3 groups: SS-13BN group (control group, n=9), DS group (model group, n=9) and GS group (Guizhi Decoction, n=9). After 10 weeks of a high-salt diet, the GS group rats were given Guizhi Decoction and other two groups were given saline at an equal volume as a vehicle. After 4 weeks' intragastric administration, rats were executed to detect the relevant indicators. Echocardiography and plasma n-terminal pro-B type natriuretic peptide (NT-proBNP) levels were used to assess cardiac function. Noradrenaline (NA) levels in the plasma and myocardium were detected to evaluate the sympathetic function. NGF and LIF expression were detected in the myocardium by Western blot or quantitative real-time PCR. Double immunofluorescence or Western blot was used to detect tyrosine hydroxylase (TH), choline acetyltransferase (CHAT) and growth associated protein 43 (GAP43) in order to reflect anatomical and functional changes of sympathetic nerves. DS group had anatomical and functional deterioration of sympathetic nerves in the decompensation period of heart failure compared with SS-13BN group. Compared with the DS group, Guizhi Decoction significantly decreased the expression of LIF mRNA/protein (P<0.01), increased the expression of NGF (P<0.05 or P<0.01), enhanced the levels of TH+/GAP43+ and TH+/CHAT+ positive nerve fibers (P<0.01), and improved the protein expression of TH and GAP43 in left ventricle, but had no effect on CHAT (P>0.05). Guizhi Decoction inhibited inflammatory infiltration and collagen deposition of myocardial injury, increased the content of myocardial NA (P<0.05), reduced the plasma NA level (P<0.01), improved cardiac function (P<0.01), and improved weight and blood pressure to some extent (P<0.05), compared with DS group. Guizhi Decoction could inhibit cholinergic transdifferentiation of sympathetic nerves, improve the anatomical and functional denervation of sympathetic nerves, and delay the progression of decompensated heart failure. The mechanism may be associated with the correction of the imbalance of NGF and LIF.

The sodium\u2013glucose co-transporter 2 inhibitor empagliflozin attenuates cardiac fibrosis and improves ventricular hemodynamics in hypertensive heart failure rats

BackgroundSodium glucose co-transporter 2 inhibitor (SGLT2i), a new class of anti-diabetic drugs acting on inhibiting glucose resorption by kidneys, is shown beneficial in reduction of heart failure hospitalization and cardiovascular mortality. The mechanisms remain unclear. We hypothesized that SGLT2i, empagliflozin can improve cardiac hemodynamics in non-diabetic hypertensive heart failure.Methods and resultsThe hypertensive heart failure model had been created by feeding spontaneous hypertensive rats (SHR) with high fat diet for 32 weeks (total n = 13). Half SHRs were randomized to be administered with SGLT2i, empagliflozin at 20 mg/kg/day for 12 weeks. After evaluation of electrocardiography and echocardiography, invasive hemodynamic study was performed and followed by blood sample collection and tissue analyses. Empagliflozin exhibited cardiac (improved atrial and ventricular remodeling) and renal protection, while plasma glucose level was not affected. Empagliflozin normalized both end-systolic and end-diastolic volume in SHR, in parallel with parameters in echocardiographic evaluation. Empagliflozin also normalized systolic dysfunction, in terms of the reduced maximal velocity of pressure incline and the slope of end-systolic pressure volume relationship in SHR. In histological analysis, empagliflozin significantly attenuated cardiac fibrosis in both atrial and ventricular tissues. The upregulation of atrial and ventricular expression of PPARα, ACADM, natriuretic peptides (NPPA and NPPB), and TNF-α in SHR, was all restored by treatment of empagliflozin.ConclusionsEmpagliflozin improves hemodynamics in our hypertensive heart failure rat model, associated with renal protection, attenuated cardiac fibrosis, and normalization of HF genes. Our results contribute some understanding of the pleiotropic effects of empagliflozin on improving heart function.

Renoprotective effects of tolvaptan in hypertensive heart failure rats depend on renal decongestion.

The vasopressin type 2 receptor antagonist tolvaptan may have renoprotective effects in patients with heart failure (HF). This study aimed to reveal the renoprotective effect of tolvaptan from the viewpoint of hemodynamic combined with catheter and ultrasound examinations in a hypertensive HF model. Dahl salt-sensitive rats (n = 24) were fed an 8% high-salt diet after the age of 6 weeks and were treated with tolvaptan (n = 16) or vehicle (control group; n = 8). The tolvaptan-treated rats were divided into two groups: a low-dose group (0.01% tolvaptan diet; Low-Tol) and a high-dose group (0.05% tolvaptan diet; High-Tol). At 24 weeks, catheterizations to measure central venous pressure (CVP) and renal medullary pressure (RMP) were performed, followed by intrarenal Doppler (IRD) studies and contrast-enhanced ultrasonography (CEUS) to evaluate renal medullary perfusion. The tolvaptan diet reduced CVP (7.7 ± 1.5, 9.0 ± 1.1, and 12.2 ± 0.8 mmHg in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001) and RMP (7.7 ± 0.8, 9.4 ± 1.3, and 13.7 ± 1.2 mmHg in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001). Tolvaptan also reduced the venous impedance index (VII) in the IRD analysis (0.18 ± 0.03, 0.26 ± 0.04, and 0.40 ± 0.08 in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001), and the time to peak intensity in CEUS (6.0 ± 0.5, 7.3 ± 1.3, 9.8 ± 1.8 s in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001). Creatinine clearance (Ccr) was preserved in both the High-Tol and Low-Tol groups compared to the control group (4.80 ± 1.9, 4.24 ± 0.8, and 1.35 ± 0.3 mg/min, respectively; p = 0.001). Ccr was negatively correlated with RMP (R = -0.76, P < 0.001), the venous impedance index (R = -0.70, p < 0.001), time to peak intensity (R = -0.75, P < 0.001), and renal fibrosis (R = -0.70, p < 0.001). In contrast, Ccr had modest correlations with systolic blood pressure (R = -0.50, P = 0.02) and left ventricular ejection fraction (R = 0.48, P = 0.03). This study revealed that the renoprotective effects of tolvaptan in a hypertensive HF model depended on renal decongestion.

Cardiac myofibrillar contractile properties during the progression from hypertension to decompensated heart failure.

Heart failure arises, in part, from a constellation of changes in cardiac myocytes including remodeling, energetics, Ca2+ handling, and myofibrillar function. However, little is known about the changes in myofibrillar contractile properties during the progression from hypertension to decompensated heart failure. The aim of the present study was to provide a comprehensive assessment of myofibrillar functional properties from health to heart disease. A rodent model of uncontrolled hypertension was used to test the hypothesis that myocytes in compensated hearts exhibit increased force, higher rates of force development, faster loaded shortening, and greater power output; however, with progression to overt heart failure, we predicted marked depression in these contractile properties. We assessed contractile properties in skinned cardiac myocyte preparations from left ventricles of Wistar-Kyoto control rats and spontaneous hypertensive heart failure (SHHF) rats at ~3, ~12, and >20 mo of age to evaluate the time course of myofilament properties associated with normal aging processes compared with myofilaments from rats with a predisposition to heart failure. In control rats, the myofilament contractile properties were virtually unchanged throughout the aging process. Conversely, in SHHF rats, the rate of force development, loaded shortening velocity, and power all increased at ~12 mo and then significantly fell at the >20-mo time point, which coincided with a decrease in left ventricular fractional shortening. Furthermore, these changes occurred independent of changes in β-myosin heavy chain but were associated with depressed phosphorylation of myofibrillar proteins, and the fall in loaded shortening and peak power output corresponded with the onset of clinical signs of heart failure.NEW & NOTEWORTHY This novel study systematically examined the power-generating capacity of cardiac myofilaments during the progression from hypertension to heart disease. Previously undiscovered changes in myofibrillar power output were found and were associated with alterations in myofilament proteins, providing potential new targets to exploit for improved ventricular pump function in heart failure.

Peripheral and Cerebral Resistance Arteries in the Spontaneously Hypertensive Heart Failure Rat: Effects of Stilbenoid Polyphenols

Hypertension is associated with aberrant structure and mechanical properties of resistance arteries. We determined the effects of resveratrol, a non-flavonoid polyphenol found in foods such as red grapes, and structurally-similar analogues (pterostilbene and gnetol) on systolic blood pressure (SBP) and resistance arteries from the spontaneously hypertensive heart failure (SHHF) rat. SBP was elevated in 17-week-old SHHF vs. Sprague-Dawley rats (normotensive control; 194 ± 3 vs. 142 ± 6 mmHg, p < 0.01) and was unaffected by resveratrol, pterostilbene, or gnetol (2.5 mg/kg/d). Geometry and mechanical properties of pressurized mesenteric resistance arteries and middle cerebral arteries were calculated from media and lumen dimensions measured at incremental intraluminal pressures. SHHF arteries exhibited remodeling which consisted of augmented media-to-lumen ratios, and this was attenuated by stilbenoid treatment. Compliance was significantly reduced in SHHF middle cerebral arteries but not mesenteric arteries vis-à-vis increased wall component stiffness; stilbenoid treatment failed to normalize compliance and wall component stiffness. Our data suggest that neither AMPK nor ERK mediate stilbenoid effects. In conclusion, we observed arterial bed-specific abnormalities, where mesenteric resistance arteries exhibited remodeling and cerebral arteries exhibited remodeling and stiffening. Resveratrol, pterostilbene, and gnetol exhibited similar abilities to attenuate vascular alterations.

Disparate Effects of Stilbenoid Polyphenols on Hypertrophic Cardiomyocytes In Vitro vs. in the Spontaneously Hypertensive Heart Failure Rat.

Stilbenoids are bioactive polyphenols, and resveratrol (trans-3,5,4′-trihydroxystilbene) is a representative stilbenoid that reportedly exerts cardioprotective actions. As resveratrol exhibits low oral bioavailability, we turned our attention to other stilbenoid compounds with a history of medicinal use and/or improved bioavailability. We determined the effects of gnetol (trans-3,5,2′,6′-tetrahydroxystilbene) and pterostilbene (trans-3,5-dimethoxy-4′-hydroxystilbene) on cardiac hypertrophy. In vitro, gnetol and pterostilbene prevented endothelin-1-induced indicators of cardiomyocyte hypertrophy including cell enlargement and protein synthesis. Gnetol and pterostilbene stimulated AMP-activated protein kinase (AMPK), and inhibition of AMPK, using compound C or shRNA knockdown, abolished these anti-hypertrophic effects. In contrast, resveratrol, gnetol, nor pterostilbene reduced blood pressure or hypertrophy in the spontaneously hypertensive heart failure (SHHF) rat. In fact, AMPK levels were similar between Sprague-Dawley and SHHF rats whether treated by stilbenoids or not. These data suggest that the anti-hypertrophic actions of resveratrol (and other stilbenoids?) do not extend to the SHHF rat, which models heart failure superimposed on hypertension. Notably, SHHF rat hearts exhibited prolonged isovolumic relaxation time (an indicator of diastolic dysfunction), and this was improved by stilbenoid treatment. In conclusion, stilbenoid-based treatment as a viable strategy to prevent pathological cardiac hypertrophy, a major risk factor for heart failure, may be context-dependent and requires further study.

Global comparison of phosphoproteins in human and rodent hearts: implications for translational studies of myosin light chain and troponin phosphorylations.

Cardiac remodeling and failure are regulated by a myriad of cardiac protein phosphorylations. In the present study, cardiac phosphoprotein patterns were examined in rodent and human hearts Left ventricular tissue samples were obtained from human systolic failing (n = 5) and control (n = 5) hearts and from two rat models of hypertensive heart failure, i.e., spontaneously hypertensive heart failure and Dahl salt-sensitive rats and corresponding controls. Phosphoproteins were separated by 2D-DIGE with Cydye staining, phosphoprotein patterns were analyzed using pixel intensity in rectified images. Specific phosphoproteins which were different in human versus rodent hearts were identified by MALDI-TOF/TOF Mass Spectrometry. Targeted pair-wise analyses showed differences (p < 0.05) in 26 % of the pixels, which included pixels containing phosphorylated troponin T, myosin light chain, peroxiredoxin, and haptoglobin. These results show differences in rodent versus human cardiac remodeling which will influence the translation rodent studies to humans in this area.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-2469-x) contains supplementary material, which is available to authorized users.

The interplay between genetic background and sexual dimorphism of doxorubicin-induced cardiotoxicity.

BackgroundDoxorubicin (DOX) is a very effective anticancer medication that is commonly used to treat hematological malignancies and solid tumors. Nevertheless, DOX is known to have cardiotoxic effects that may lead to cardiac dysfunction and failure. In experimental studies, female animals have been shown to be protected against DOX-induced cardiotoxicity; however, the evidence of this sexual dimorphism is inconclusive in clinical studies. Therefore, we sought to investigate whether genetic background could influence the sexual dimorphism of DOX-induced cardiotoxicity.MethodsMale and female Wistar Kyoto (WKY) and Spontaneous Hypertensive Heart Failure (SHHF) rats were used. DOX was administered in eight doses of 2 mg/kg/week and the rats were followed for an additional 12 weeks. Cardiac function was assessed by trans-thoracic echocardiography, systolic blood pressure was measured by the tail cuff method, and heart and kidney tissues were collected for histopathology.ResultsFemale sex protected against DOX-induced weight loss and increase in blood pressure in the WKY rats, whereas it protected against DOX-induced cardiac dysfunction and the elevation of cardiac troponin in SHHF rats. In both strains, female sex was protective against DOX-induced nephrotoxicity. There was a strong correlation between DOX-induced renal pathology and DOX-induced cardiac dysfunction.ConclusionsThis study highlights the importance of studying the interaction between sex and genetic background to determine the risk of DOX-induced cardiotoxicity. In addition, our findings suggest that DOX-induced nephrotoxicity may play a role in DOX-induced cardiac dysfunction in rodent models.

Long-term physiological T3 supplementation in hypertensive heart disease in rats.

Animal studies suggest that hypertension leads to cardiac tissue hypothyroidism, a condition that can by itself lead to heart failure. We have previously shown that short-term thyroid hormone treatment in Spontaneously Hypertensive Heart Failure (SHHF) rats near heart failure is beneficial. This study tested the hypothesis that therapeutic, long-term T3 treatment in SHHF rats can prevent or attenuate cardiac dysfunction. Female SHHF rats were treated orally with a physiological T3 dose (0.04 μg/ml) from 12 to 24 mo of age. Age-matched female SHHF and Wistar-Kyoto rats served as hypertensive and normotensive controls, respectively. SHHF rats had reduced serum free thyroid hormone levels and cardiac tissue T3 levels, LV dysfunction, and elevated LV collagen content compared with normotensive controls. Restoration of serum and cardiac tissue thyroid hormone levels in T3-treated rats was associated with no change in heart rate, but strong trends for improvement in LV systolic function and collagen levels. For instance, end-systolic diameter, fractional shortening, systolic wall stress, and LV collagen levels were no longer significantly different from controls. In conclusion, longstanding hypertension in rats led to chronic low serum and cardiac tissue thyroid hormone levels. Long-term treatment with low-dose T3 was safe. While cardiac dysfunction could not be completely prevented in the absence of antihypertensive treatment, T3 may offer additional benefits as an adjunct therapy with possible improvement in diastolic function.

Variability in ozone-induced pulmonary injury and inflammation in healthy and cardiovascular-compromised rat models

The molecular bases for variability in air pollutant-induced pulmonary injury due to underlying cardiovascular (CVD) and/or metabolic diseases are unknown. We hypothesized that healthy and genetic CVD-prone rat models will exhibit exacerbated response to acute ozone exposure dependent on the type and severity of disease. Healthy male 12–14-week-old Wistar Kyoto (WKY), Wistar (WS) and Sprague Dawley (SD); and CVD-compromised spontaneously hypertensive (SH), Fawn-Hooded hypertensive (FHH), stroke-prone spontaneously hypertensive (SHSP), obese spontaneously hypertensive heart failure (SHHF) and obese JCR (JCR) rats were exposed to 0.0, 0.25, 0.5, or 1.0 ppm ozone for 4 h; pulmonary injury and inflammation were analyzed immediately following (0-h) or 20-h later. Baseline bronchoalveolar lavage fluid (BALF) protein was higher in CVD strains except for FHH when compared to healthy. Ozone-induced increases in protein and inflammation were concentration-dependent within each strain but the degree of response varied from strain to strain and with time. Among healthy rats, SD were least affected. Among CVD strains, lean rats were more susceptible to protein leakage from ozone than obese rats. Ozone caused least neutrophilic inflammation in SH and SHHF while SHSP and FHH were most affected. BALF neutrophils and protein were poorly correlated when considering the entire dataset (r = 0.55). The baseline and ozone-induced increases in cytokine mRNA varied markedly between strains and did not correlate with inflammation. These data illustrate that the degree of ozone-induced lung injury/inflammation response is likely influenced by both genetic and physiological factors that govern the nature of cardiovascular compromise in CVD models.

Assessment of the early stage of cardiac remodeling of spontaneously hypertensive heart failure rats using the quantitative 3-dimensional analysis provided by acipimox-enhanced FDG-PET

Spontaneously hypertensive heart failure rats (SHHF) appear to constitute an original model for analyzing the evolution of the metabolic syndrome towards heart failure. This study aimed to characterize early cardiac dysfunction and remodeling in SHHF rats: (1) as compared with spontaneously hypertensive rats (SHR) and with a control group of Kyoto rats (WKY), and (2) by using the 3-dimensional quantitative analysis provided by acipimox-enhanced positron emission tomography (PET) with (18)F-fluorodesoxyglucose (FDG). Left ventricular (LV) ejection fraction (EF) and volume were quantified by automatic software on the FDG-PET images recorded in SHR (n = 20), SHHF (n = 18) and WKY-rats (n = 19) at ages 3 or 10 months old. Arterial blood pressure was determined by cardiac catheterization and cardiac fibrosis was quantified after sacrifice. Blood pressure was similarly elevated in SHR and SHHF rats (respective systolic blood pressures at 10-months: 199 ± 39 vs. 205 ± 2 mmHg), but SHHF rats had higher body mass than SHR rats (at 10-months, 630 ± 36 vs. 413 ± 27 g, p < 0.05) and higher blood levels of cholesterol and of triglycerides. At 3 months, cardiac parameters did not show significant differences between groups but at 10-months, SHHF and SHR rats exhibited an enhancement in myocardial mass and fibrosis associated with a clear decline in LV-EF (SHHF: 46 ± 6 %; SHR: 47 ± 5 %) as compared with WKY (56 ± 6 %, p < 0.01 for both comparisons). Cardiac remodeling of SHHF rats was clearly observable by FDG-PET from the age of 10-months, but in a similar way to that observed for SHR rats, suggesting a predominant role of hypertension.