Coronary Artery Ligation In Rats Research Articles

Long-acting CRF2 peptide agonist improves cardiac function in a rat heart failure model

Abstract Introduction Corticotropin-releasing factor receptor type 2 (CRF2) is a G protein-coupled receptor largely expressed in the cardiorenal system. Upon CRF2 activation, endogenous ligands such as urocortin-2 (UCN-2) or urocortin-3 (UCN-3) have been reported to increase cardiac function, decrease vascular resistance and improve natriuresis and diuresis in heart failure (HF) patients and in various experimental heart failure settings. However UCN-2 or -3 suffer from a very short half-life which markedly limit further clinical investigations in HF patients. For this purpose, a very long acting CRF2 peptide agonist has been developed. Objectives The aim of this study is to determine the acute effect on cardiac hemodynamic of a long acting CRF2 peptide agonist, COR-1167, in a rat model of chronic heart failure. Methods In 10-week-old Wistar rats, a total occlusion of the left anterior descending coronary artery was performed to induce myocardial infarction. Twelve weeks after myocardial infarction, rats had developed heart failure and received COR-1167 at the dose of 0.3 µg/kg or 1 µg/kg, or placebo, administered SC. Left ventricular dimensions and function were then assessed by echocardiography and left ventricular pressure-volume analysis. Results Three months after left coronary artery ligation rats displayed the classical features of heart failure as illustrated by an increase in left ventricular diastolic diameter and reduced ejection fraction, and decreases in LV end-systolic pressure, dP/dtmax and LV end-systolic pressure volume relationship. Major LV diastolic dysfunction developed, as shown by the increases in LV end-diastolic pressure, and LV end-diastolic pressure volume relationship and the decrease in dP/dtmin. Echocardiography and left ventricular pressure-volume analysis showed that COR-1167 at 0.3 and 1 µg/kg SC improved in a dose-dependent manner cardiac contractility and relaxation as assessed by LVESPVR and LVEDPVR, respectively. In addition, stroke volume and cardiac output were significantly ameliorated by COR-1167 at 1.0 µg/kg SC, with no change in heart rate. Conclusion Single acute administration of COR-1167 improved cardiac function in a rat model of heart failure with reduced ejection fraction. Altogether these results confirm that CRF2 agonism is an attractive therapeutic target for the treatment of heart failure.

S-51-4: RENAL DENERVATION IMPROVES FLUID RETENTION BY MODULATING RENAL SGLT2 FUNCTION IN RATS WITH HEART FAILURE

Objective: Renal denervation (RDN) has been developed as a neuromodulation therapy for patients with treatment-resistant hypertension. RDN is expected to prevent not only hypertension but also heart failure (HF). Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been shown to ameliorate HF and widely used for HF patients. The present study was conducted to assess the effect of RDN on HF and the interaction between renal sympathetic nerves and SGLT2 function in HF. Design and method: HF was induced by coronary artery ligation in rats. Four weeks after coronary artery ligation surgery, surgical bilateral RDN was performed. Western blot analysis was performed to assess the expression levels of SGLT2. One week after RDN surgery, as a functional test for SGLT2 activation, natriuretic response to intravenous injection of SGLT2 inhibitor dapagliflozin (0.5 mg/kg, i.v.) was investigated. Furthermore, the changes in expression and localization of SGLT2 were assessed in human embryonic kidney cells treated with norepinephrine directly, in vitro. Results: Western blot analysis indicated that renal SGLT2 expression is increased in rats with HF. RDN significantly reduced enhanced renal SGLT2 expression in HF. Natriuretic response to dapagliflozin were greater in HF than Sham (Cumulative sodium excretion at 120 min, 227 ± 35 vs. 133 ± 13 μEq/gkw, P < 0.05, n = 6). RDN significantly attenuated natriuretic response to dapagliflozin in HF (Cumulative sodium excretion at 120 min, 138 ± 19 vs. 227 ± 35 μEq/gkw, P < 0.05, n = 6). Direct application of norepinephrine on human embryonic kidney cells, in vitro, resulted in an increased expression of SGLT2 and specifically promoted the translocation of SGLT2 from the cytosol to the cell surface (Cytosolic SGLT2/GAPDH 0.51 ± 0.05 vs. 0.86 ± 0.08, Membranous SGLT2/Na-K-ATPase 1.06 ± 0.10 vs. 0.54 ± 0.03, P < 0.01, n = 6). Moreover, RDN increased the cytosolic SGLT2 while decreasing membranous SGLT2 in the kidneys of rats with HF (Cytosolic SGLT2/GAPDH 1.30 ± 0.11 vs. 0.58 ± 0.09, Membranous SGLT2/Na-K-ATPase 0.51 ± 0.10 vs. 2.08 ± 0.08, P < 0.01, n = 6). Conclusions: These findings suggest that the excessive activation of renal sympathetic nerves in HF increases the expression of SGLT2 protein trafficked by norepinephrine to cell membrane in proximal tubules resulting in greater sodium retention associated with HF condition. RDN mitigates the enhanced expression and activity of SGLT2 and ameliorates the subsequent sodium and water retention associated with HF, suggesting the potential therapeutic use of RDN for HF.

Olive oil protects against progression of heart failure by inhibiting remodeling of heart subsequent to myocardial infarction in rats

We examined the beneficial effects of olive oil against heart failure post‐myocardial infarction (PMI), induced by coronary artery ligation in rats. Animals were divided into sham and ligated groups and fed either regular chow, olive oil (10% wt/wt), or corn oil (10% wt/wt) and were followed up to 16 weeks. On the echocardiography at 3 days (PMI), in the ligated regular chow (LRC), ligated olive oil (LOO), and ligated corn oil (LCO) left ventricular ejection fraction (LVEF) decrease was 12.14%, 16.42%, and 17.53% from the baseline, respectively. However, only LOO group improved LVEF significantly at 16 weeks PMI and became comparable with all sham groups. Both scar formation and collagen deposition at 16 weeks PMI were less pronounced in the LOO group. Myocardial TNF‐α level at 4 weeks of PMI increased by 176%, 11%, and 181% in the LRC, LOO, and LCO groups, respectively. Plasma TNF‐α levels in LOO were significantly lower than LRC group after 4 weeks of PMI. Myocardial redox ratio (reduced glutathione/oxidized glutathione) decreased at 4 weeks PMI by 44.4%, 16.4%, and 36.9% in the LRC, LOO, and LCO groups, respectively, compared to the baseline. These changes in the redox ratio at 16 weeks PMI were further exacerbated in the LRC and LCO groups. Lipid hydroperoxides formation increased at 4 weeks PMI by 137.4%, 14.6%, and 97.1% in the LRC, LOO, and LCO groups, respectively. Since coronary artery ligation decreased left ventricular ejection fraction, increased myocardial TNF‐α and oxidative stress, and since olive oil was able to inhibit these effects, it is proposed that dietary olive oil modulates cardiac remodeling and heart failure subsequent to myocardial infarction.

Recombinant Klotho Protein Ameliorates Myocardial Ischemia/Reperfusion Injury by Attenuating Sterile Inflammation

Currently, no effective therapy and potential target have been elucidated for preventing myocardial ischemia and reperfusion injury (I/R). We hypothesized that the administration of recombinant klotho (rKL) protein could attenuate the sterile inflammation in peri-infarct regions by inhibiting the extracellular release of high mobility group box-1 (HMGB1). This hypothesis was examined using a rat coronary artery ligation model. Rats were divided into sham, sham+ rKL, I/R, and I/R+ rKL groups (n = 5/group). Administration of rKL protein reduced infarct volume and attenuated extracellular release of HMGB1 from peri-infarct tissue after myocardial I/R injury. The administration of rKL protein inhibited the expression of pro-inflammatory cytokines in the peri-infarct regions and significantly attenuated apoptosis and production of intracellular reactive oxygen species by myocardial I/R injury. Klotho treatment significantly reduced the increase in the levels of circulating HMGB1 in blood at 4 h after myocardial ischemia. rKL regulated the levels of inflammation-related proteins. This is the first study to suggest that exogenous administration of rKL exerts myocardial protection effects after I/R injury and provides new mechanistic insights into rKL that can provide the theoretical basis for clinical application of new adjunctive modality for critical care of acute myocardial infarction.

Evaluation of Cardiovascular Experiment Animal

Abstract: In vivo models of myocardial infarction induced by coronary artery ligation in rats usually suffer from high early mortality and a low rate of induction. This study investigated the time course initiation of chronic myocardial infarction in albino rats and the possibility of reducing early mortality rate due to myocardial infarction by modification of the surgical technique. CAL was carried out by passing the suture through the pericardial layer around the midway of the left anterior descending coronary artery including a small area of the myocardium to avoid mechanical damage to the heart geometry. In addition, the role of endothelin-1 in rat heart with congestive heart failure was critically assessed. Time course initiation experiments were designed by sacrificing the animals at different time intervals and by carrying out physiological, biochemical, histopathological, electron microscopical and immunohistochemical studies. Specific markers of myocardial injury, viz. cardiac troponin-T, high sensitivity C-reactive protein, lactate dehydrogenase and fibrinogen were measured at different time points. Serum marker enzymes and activities of lysosomal hydrolases were found to be elevated on the eighth day post-ligation. Histopathological studies demonstrated focal areas showing fibrovascular tissue containing fibroblasts, collagenous ground substance and numerous small capillaries replacing cardiac muscle fibers. Transmission electron micrographs exhibited mitochondrial changes of well-developed irreversible cardiac injury, viz. swelling, disorganization of cristae, appearance of mitochondrial amorphous matrix densities, and significant distortion of muscle fibers and distinct disruption of the intercalated discs. Immune blotting studies confirmed the presence of alpha 2-macroglobulin which supported the inflammatory response. The severity of the CMI was inferred by the measurement of the level of ET-1 in plasma and left ventricle which was significantly higher in the CMI rats than in the sham-operated rats. Immunohistochemical studies at different time intervals showed that there was a significant immunoexpression of ET-1 on the eighth day post-ligation. This study conclusively showed that ligation of left anterior descending artery minimised mortality and ET-1 was expressed during CMI.

Spatio-temporal regulation of calpain activity after experimental myocardial infarction in vivo

BackgroundCalpains are calcium activated cysteine proteases that play a pivotal role in the pathophysiology of cardiac remodeling. MethodsHere, we performed left anterior descending coronary artery ligation in rats as a model for ischemic systolic heart failure and examined the time- and region-specific regulation of calpain-1 and calpain-2 in the left ventricular myocardium. ResultsFollowing anterior wall myocardial infarction, calpain activity was significantly increased restricted to the ischemic anterior area at days 1, 5 and 14. No changes in calpain activity at neither time point were detected in the borderzone and remote posterior area of the left ventricle. Of note, calpain activity in the infarcted anterior myocardium was regulated differentially in the acute vs. subacute and chronic phase. In the acute phase, calpain translocation to the plasma membrane and attenuation of the expression of its endogenous inhibitor, calpastatin, were identified as the driving forces. In the subacute and chronic phase, calpain activity was regulated at the level of protein expression that was shown to be essentially independent of transcriptional activity. ConclusionsWe conclude that myocardial infarction leads to a distinct calpain regulation pattern in the left ventricular myocardium that is region specific and time dependent. Considering the results from our previous studies, a spatio-temporal interaction between calpains and calcium dependent natriuretic peptide production in the infarcted myocardium is possible. General significanceOur results shed more light in the differential regulation of calpain activity in the myocardium and might aid in the development of targeted post-infarct and/or heart failure therapeutics.

Carbonic anhydrase IX and hypoxia-inducible factor 1 attenuate cardiac dysfunction after myocardial infarction.

Myocardial infarction (MI) is one of the leading causes of death worldwide. Prognosis and mortality rate are directly related to infarct size and post-infarction pathological heart remodeling, which can lead to heart failure. Hypoxic MI-affected areas increase the expression of hypoxia-inducible factor (HIF-1), inducing infarct size reduction and improving cardiac function. Hypoxia translocates HIF-1 to the nucleus, activating carbonic anhydrase IX (CAIX) transcription. CAIX regulates myocardial intracellular pH, critical for heart performance. Our objective was to investigate CAIX participation and relation with sodium bicarbonate transporters 1 (NBC1) and HIF-1 in cardiac remodeling after MI. We analyzed this pathway in an "in vivo" rat coronary artery ligation model and isolated cardiomyocytes maintained under hypoxia. Immunohistochemical studies revealed an increase in HIF-1 levels after 2 h of infarction. Similar results were observed in 2-h infarcted cardiac tissue (immunoblotting) and in hypoxic cardiomyocytes with a nuclear distribution (confocal microscopy). Immunohistochemical studies showed an increase CAIX in the infarcted area at 2 h, mainly distributed throughout the cell and localized in the plasma membrane at 24 h. Similar results were observed in 2 h in infarcted cardiac tissue (immunoblotting) and in hypoxic cardiomyocytes (confocal microscopy). NBC1 expression increased in cardiac tissue after 2 h of infarction (immunoblotting). CAIX and NBC1 interaction increases in cardiac tissue subjected to MI for 2h when CAIX is present (immunoprecipitation). These results suggest that CAIX interacts with NBC1 in our infarct model as a mechanism to prevent acidic damage in hypoxic tissue, making it a promising therapeutic target.

AIM2-driven inflammasome activation in heart failure.

Interleukin-1β (IL-1β) is an important pathogenic factor in cardiovascular diseases including chronic heart failure (HF). The CANTOS trial highlighted that inflammasomes as primary sources of IL-1 β are promising new therapeutic targets in cardiovascular diseases. Therefore, we aimed to assess inflammasome activation in failing hearts to identify activation patterns of inflammasome subtypes as sources of IL-1β. Out of the four major inflammasome sensors tested, expression of the inflammasome protein absent in melanoma 2 (AIM2) and NLR family CARD domain-containing protein 4 (NLRC4) increased in human HF regardless of the aetiology (ischaemic or dilated cardiomyopathy), while the NLRP1/NALP1 and NLRP3 (NLR family, pyrin domain containing 1 and 3) inflammasome showed no change in HF samples. AIM2 expression was primarily detected in monocytes/macrophages of failing hearts. Translational animal models of HF (pressure or volume overload, and permanent coronary artery ligation in rat, as well as ischaemia/reperfusion-induced HF in pigs) demonstrated activation pattern of AIM2 similar to that of observed in end-stages of human HF. In vitro AIM2 inflammasome activation in human Tohoku Hospital Pediatrics-1 (THP-1) monocytic cells and human AC16 cells was significantly reduced by pharmacological blockade of pannexin-1 channels by the clinically used uricosuric drug probenecid. Probenecid was also able to reduce pressure overload-induced mortality and restore indices of disease severity in a rat chronic HF model in vivo. This is the first report showing that AIM2 and NLRC4 inflammasome activation contribute to chronic inflammation in HF and that probenecid alleviates chronic HF by reducing inflammasome activation. The present translational study suggests the possibility of repositioning probenecid for HF indications.

Renal denervation improves sodium excretion in rats with chronic heart failure: effects on expression of renal ENaC and AQP2.

Previously we have shown that increased expression of renal epithelial sodium channels (ENaC) may contribute to the renal sodium and water retention observed during chronic heart failure (CHF). The goal of this study was to examine whether renal denervation (RDN) changed the expressions of renal sodium transporters ENaC, sodium-hydrogen exchanger-3 proteins (NHE3), and water channel aquaporin 2 (AQP2) in rats with CHF. CHF was produced by left coronary artery ligation in rats. Four weeks after ligation surgery, surgical bilateral RDN was performed. The expression of ENaC, NHE3, and AQP2 in both renal cortex and medulla were measured. As a functional test for ENaC activation, diuretic and natriuretic responses to ENaC inhibitor benzamil were monitored in four groups of rats (Sham, Sham+RDN, CHF, CHF+RDN). Western blot analysis indicated that RDN (1 wk later) significantly reduced protein levels of α-ENaC, β-ENaC, γ-ENaC, and AQP2 in the renal cortex of CHF rats. RDN had no significant effects on the protein expression of kidney NHE3 in both Sham and CHF rats. Immunofluorescence studies of kidney sections confirmed the reduced signaling of ENaC and AQP2 in the CHF+RDN rats compared with the CHF rats. There were increases in diuretic and natriuretic responses to ENaC inhibitor benzamil in rats with CHF. RDN reduced the diuretic and natriuretic responses to benzamil in CHF rats. These findings suggest a critical role for renal nerves in the enhanced expression of ENaC and AQP2 and subsequent pathophysiology of renal sodium and water retention associated with CHF.NEW & NOTEWORTHY This is the first study to show in a comprehensive way that renal denervation initiated after a period of chronic heart failure reduces the expression of epithelial sodium channels and aquaporin 2 leading to reduced epithelial sodium channel function and sodium retention.

Development of a Novel Sodium-Hydrogen Exchanger Inhibitor for Heart Failure

This study was designed to determine the potential therapeutic effects of a new sodium-hydrogen exchanger (NHE-1) inhibitor in the rat coronary artery ligation model of chronic heart failure. After the induction of acute myocardial infarction, rats were entered into a randomly designed pilot dose study from 0.3 mg/kg, 1.0 mg/kg, and 3.0 mg/kg. Solid state micrometer hemodynamics, echocardiographic, and pressure-volume relationships were measured after 6 weeks of treatment. Treatment with this NHE-¬1 inhibitor at 3 mg/kg increased (P<0.05) ejection fraction from 23±3% (N=6) to 33±2% (N=13), while the 1 mg/kg dose decreased (P<0.05) the infarct size in CHF rats from 21.7±1.4% (N=7) to 15.9±0.7% (N=3) and prevented (P<0.05) dilata¬tion of the left ventricle in CHF rats in diastole (1.0±0.1 cm, N=6) to 0.9±0.1 cm, N=10) and in systole (0.9±0.1 cm, N=6) to 0.8±0.1, N=10). These study results suggest that this new NHE-1 inhibitor may be potentially useful in treating CHF with an improvement in maladaptive left ventricle remodeling. Because the mechanism of action of this agent is entirely different than the currently applied approach in treating CHF that focuses on aggressive neuro-hormonal blockade and because this agent does not adversely affect important hemodynamic variables, further investigations with this agent may be warranted.

Mangiferin Attenuates Myocardial Ischemia-Reperfusion Injury via MAPK/Nrf-2/HO-1/NF-κB In Vitro and In Vivo.

The aim of this study was to investigate the cardioprotective effect of mangiferin (MAF) in vitro and in vivo. Oxidative stress and inflammatory injury were detected in coronary artery ligation in rats and also in hypoxia-reoxygenation- (H/R-) induced H9c2 cells. MAF inhibited myocardial oxidative stress and proinflammatory cytokines in rats with coronary artery occlusion. The ST segment of MAF treatment groups also resumed. Triphenyltetrazolium chloride (TTC) staining and pathological analysis showed that MAF could significantly reduce myocardial injury. In vitro data showed that MAF could improve hypoxia/reoxygenation- (H/R-) induced H9c2 cell activity. In addition, MAF could significantly reduce oxidative stress and inflammatory pathway protein expression in H/R-induced H9c2 cells. This study has clarified the protective effects of MAF on myocardial injury and also confirmed that oxidative stress and inflammation were involved in the myocardial ischemia-reperfusion injury (I/R) model.

Heat-shock protein 90 modulates cardiac ventricular hypertrophy via activation of MAPK pathway

The Raf/MAPK/ERK kinase (Mek)/extracellular signal-regulated kinases (Erk) pathway is activated in cardiac hypertrophy after a myocardial infarction. Although heat-shock protein 90 (Hsp90) may regulate the Raf/Mek/Erk signal pathway, the role of Hsp90 in pathophysiological cardiac hypertrophy remains unclear. In this study, we examined the role of Hsp90 in this pathway in cardiac hypertrophy under in vivo and in vitro experimental conditions.Cultured rat cardiomyocytes were treated with the Hsp90 inhibitor 17-(allylamino)-17-dimethoxy-geldanamycin (17-AAG) and proteasome inhibitor MG-132, and then incubated with endothelin-1 (ET) to induce hypertrophy of the cells. The ET-induced increase in the cell size was attenuated by 17-AAG pretreatment. Immunoblot analysis revealed that the c-Raf content of ET-treated cardiomyocytes was decreased in the presence of 17-AAG. An increase in phosphorylation levels of Erk1/2 and GATA4 in ET-treated cardiomyocytes was also attenuated by the 17-AAG pretreatment.Myocardial infarction was produced by ligation of the left ventricular coronary artery in rats, and then 17-AAG was intraperitoneally administered to the animals starting from the 2ndweek after coronary artery ligation (CAL). CAL-induced increases in the heart weight and cross-sectional area were attenuated by 17-AAG treatment. CAL rats showed signs of chronic heart failure with cardiac hypertrophy, whereas cardiac function in CAL rats treated with 17-AAG was not reduced. Treatment of CAL rats with 17-AAG caused a decrease in the c-Raf content and Erk1/2 and GATA4 phosphorylation levels.These findings suggest that Hsp90 is involved in the activation of the Raf/Mek/Erk pathway via stabilization of c-Raf in cardiomyocytes, resulting in the development of cardiac hypertrophy following myocardial infarction.

3-Bromo-4,5-Dihydroxybenzaldehyde Protects Against Myocardial Ischemia and Reperfusion Injury Through the Akt-PGC1α-Sirt3 Pathway.

Natural marine products are useful candidates for the treatment of oxidative and inflammatory diseases, including myocardial ischemia. 3-bromo-4,5 - dihydroxybenzaldehyde (BDB), a natural bromophenol isolated from marine red algae, has been shown to display anti-microbial, anti-oxidative, anti-cancer, anti-inflammatory, and free radical scavenging activities. In this study, the potential protective effects of BDB against myocardial ischemia and reperfusion (IR) injury was investigated in an in vitro model mimicked by oxygen and glucose deprivation (OGD) in cardiomyocytes and in an in vivo model induced by coronary artery ligation in rats. The results showed that BDB attenuated the OGD-induced cytotoxicity in a dose-dependent manner, with no toxic effect when treated alone. BDB significantly decreased apoptosis and the cleavage of caspase-3 after OGD. We found that OGD-induced oxidative stress, as evidenced by increases of reactive oxygen species (ROS) and lipid peroxidation, as well as mitochondrial dysfunction, as measured by mitochondrial reporter gene, cytochrome c release and ATP synthesis, were markedly attenuated by BDB treatment. In addition, BDB increased the enzymatic activities of mitochondrial antioxidant enzymes, including IDH2, GSH-Px and SOD2. Western blot analysis showed that BDB increased Akt phosphorylation and upregulated the expression of Sirt3 and PGC1α after OGD. Furthermore, BDB-induced protection in cardiomyocytes was partially reversed by the Akt inhibitor and downregulation of PGC1α. BDB also attenuated myocardial contractile dysfunction and activated the Akt-PGC1α-Sirt3 pathway in vivo. All these data suggest that BDB protects against myocardial IR injury through activating the Akt-PGC1α-Sirt3 pathway.

Shenfu Formula reduces cardiomyocyte apoptosis in heart failure rats by regulating microRNAs

Ethnopharmacological relevanceShenfu decoction consists of the water extract from the dried root or rootstalk of Panax ginseng C. A. Mey (Asian ginseng) and the lateral root of Aconitum carmichaeli Debx (Fuzi, Heishunpian in Chinese). Shenfu Formula has been used as a folk Chinese medicine for thousands of years. Recent studies have shown that Shenfu injection can enhance cardiac function and regulate arrhythmia. Aim of the studyShenfu Formula plays an important role in the treatment of heart failure. However, its microRNA-mediated mechanisms are still not fully understood. Thus, we established a heart failure model in rats to investigate the microRNA mechanism of Shenfu Formula in cardiac function and apoptosis. Materials and methodsThe heart failure animal model was established via left-anterior descending coronary artery ligation in rats. Seven days after surgery, Shenfu Formula was given to the heart failure rats, which were selected by echocardiography with an LVEF< 45%. After Shenfu Formula was given intragastrically for 30 days, blood samples were drawn, the heart was excised after echocardiography, and echocardiographic parameters and apoptosis-related proteins were further examined. Fas/Fas-L and Bcl-2/Bax proteins were analyzed by Western blot, and microRNAs were evaluated using Affymetrix GeneChip miRNA arrays. ResultsShenfu Formula increased the left ventricular ejection fraction, improved the hemodynamic index of heart failure rats, and decreased serum brain natriuretic peptide (BNP) levels. Shenfu Formula also decreased the positive rate of myocardial cells as detected by the TUNEL method and significantly suppressed caspase 3 expression. Moreover, we found that Shenfu Formula can regulate the initiative factors Fas/Fas-L in the intrinsic pathway and Bcl-2/Bax in the extrinsic apoptosis pathway to suppress apoptosis in heart failure rats. Finally, Shenfu Formula potentially alters the balance of microRNAs involved in activating and inhibiting apoptosis, ultimately suppressing apoptosis; this leads to changes in the gene expression profiles of microRNAs targets. ConclusionShenfu Granule can effectively improve cardiac function in heart failure rats, and the anti-apoptosis effects of Shenfu Formula are potential mechanisms for inhibiting heart failure.

Abstract 12654: PBI-4050 Therapy Selectively Improves Pulmonary Hypertension, Lung Remodeling and Right Ventricular Function in Heart Failure With Reduced Ejection Fraction

Introduction: There is currently no approved treatment for the most prevalent form of PH that is associated with left heart disease (Group II PH). Heart failure with reduced ejection fraction (HFrEF) causes lung remodeling characterized by myofibroblasts proliferation and fibrosis leading to a restrictive lung syndrome contributing to PH and RV dysfunction. Hypothesis: We evaluated PBI-4050, a novel first-in-class agent with anti-fibrotic and anti-proliferative actions, for the treatment of PH in a model of HFrEF. Methods: HFrEF was induced by myocardial infarction (MI) after coronary artery ligation in rats. Two weeks after surgery, sham-operated and MI groups were treated with PBI-4050 (200 mg/kg/day by gavage) or with saline for 3 weeks. Animals were analyzed according to pathological infarct size into large MI (≥35% LV) and small to medium MI (&lt; 35%). Hemodynamic evaluation was performed with microtip cathethers and lung function testing evaluated with a Flexivent respirator. Cardiac ultrasound was performed at 2 weeks and at 5 weeks. Scar size and lung fibrosis were quantified by histology. Results: Pathological infarct size correlated with echocardiographic wall motion score index (r 2 =0.73, p&lt;0.001). Large MI (≥35% LV) resulted in PH and RVH with a restrictive lung syndrome. For a similar infarct size, PBI-4050 did not affect LV function but markedly reduced PH and RVH. The compensatory increase in RV contractility was normalized by PBI-4050. PBI-4050 reduced lung remodeling evidenced by a reduction in lung weight and improved respiratory compliance. Finally, lung fibrosis was reduced by PBI-4050 with histological evidence of reduced alveolar wall cellular proliferation. Conclusions: PBI-4050 effectively reduces PH and RVH in HFrEF by reducing lung fibrosis and remodeling. This novel agent decreases the associated restrictive lung syndrome and recovers RV function without affecting LV function. PBI-4050 is a promising therapy for group II PH.

Sleep-related changes in cardiovascular autonomic regulation in left coronary artery ligation rats: Neural mechanism facilitating arrhythmia after myocardial infarction

BackgroundAutonomic imbalance with increased sympathetic and decreased parasympathetic activities is observed in patients after myocardial infarction (MI). We aimed to investigate sleep-related changed in autonomic regulation in left coronary artery (LCA) ligation rats. MethodsWireless transmission of polysomnographic recording was performed in sham and LCA ligation male rats during normal daytime sleep with and without atenolol treatment. Spectral analyses of the electroencephalogram (EEG) and electromyogram (EMG) were evaluated to define active waking (AW), quiet and paradoxical sleeps (QS, PS). Cardiac autonomic activities were measured by analyzing the power spectrum of heart rate variability (HRV). EEG, EMG and HRV were recorded over 6h for consecutive 3days in all groups. ResultsIn LCA ligation group, there were higher LF and LF/HF ratio on QS phase, but not AW and PS phases, compared to atenolol treated sham and LCA ligation groups, respectively. The HF component was not significantly changed on all groups in both sleep and awake phases. Sleep interruption was more frequent in LCA ligation rats compared to sham, and it was not found in LCA ligation with atenolol treatment group. Increased AW, PS and decreased QS time were noted in LCA ligation group, compared to sham and it was restored to baseline in LCA ligation with atenolol treatment group. ConclusionsOur results demonstrate significant sleep fragmentations with sympathetic hyperactivity during QS stages after MI, and atenolol could restore the autonomic dysfunction and sleep disturbance. The finding explains the cause of sleep-related fetal arrhythmia and sudden cardiac death after MI.

Carbonic anhydrase inhibitors reduce cardiac dysfunction after sustained coronary artery ligation in rats.

Two potent carbonic anhydrase (CA) inhibitors with widely differing membrane permeability, poorly diffusible benzolamide (BZ), and highly diffusible ethoxzolamide (ETZ) were assessed to determine whether they can reduce cardiac dysfunction in rats subjected to coronary artery ligation (CAL)-induced myocardial infarction. Rats with evidence of heart failure (HF) at 32 weeks following a permanent left anterior coronary artery occlusion were treated with placebo, BZ, or ETZ (4 mg kgday-1) for 4 weeks at which time left ventricular function and structure were evaluated. Lung weight/body weight (LW/BW) ratio increased in CAL rats by 17±1% vs. control, suggesting pulmonary edema. There was a trend for BZ and ETZ to ameliorate the increase in LW/BW by almost 50% (9±5% and 9±8%, respectively, versus CAL) (P=.16, NS). Echocardiographic assessment showed decreased left ventricular midwall shortening in HF rats, 21±1% vs. control 32±1%, which was improved by BZ to 29±1% and ETZ to 27±1%, and reduced endocardial shortening in HF rats 38±3% vs. control 62±1%, partially restored by BZ and ETZ to ~50%. Expression of the hypoxia-inducible membrane-associated CAIX isoform increased by ~60% in HF rat hearts, and this effect was blocked by ETZ. We conclude that CAL-induced myocardial interstitial fibrosis and associated decline in left ventricular function were diminished with BZ or ETZ treatment. The reductions in cardiac remodeling in HF with both ETZ and BZ CA inhibitors suggest that inhibition of a membrane-bound CA appears to be the critical site for this protection.

Abstract 48: Differentiation of Moderate and Severe Ischemic Heart Failure by Invasive and Non-invasive Assessments of Diastolic Function in a Rat Model of Chronic Heart Failure

Background: This work is designed to determine if specific left ventricle (LV) pressure-volume relations, hemodynamic, and echo derived parameters of diastolic function are able to separate severe from moderate CHF in rats with left coronary artery occlusion. Hypothesis: Echocardiographic indices of diastolic function, end-diastolic pressure (EDP), dead volume, stiffness constants (k), and pressure volume relations predict the severity of CHF in infarcted rats. Methods: Male Sprague Dawley rats (N=14) were randomized to undergo left coronary artery ligation or sham operation. Echocardiography was performed at 3 and 6 weeks post coronary ligation. The rats were categorized into moderate or severe CHF according to their LVEDP at 6 weeks post ligation. Invasive hemodynamic measurements with solid state micro manometer pressure catheters as well as diastolic pressure-volume relation values were obtained at the 6 week end point. Results: Moderate and severe CHF rats had significantly (P&lt;0.05) elevated left ventricular (LV) end-diastolic pressure (LV EDPs), prolonged time constants of LV relaxation (tau), and decreased peak development pressures. When moderate versus severe CHF rats were separated based on LV EDP, early diastolic anterior wall radial relaxation velocity as well as e’, and E/e’ had strong correlations with invasive hemodynamic measurements of diastolic functions. There was a trend towards decreased compliance as measured by stiffness constants in severe heart failure group. Differences (P&lt;0.05) in dead volume, mean arterial pressure (MAP), tau, and ejection fraction (EF) were also displayed. End diastolic pressure-volume analyses illustrated significant differences in plot positioning and curvature. Conclusion: While it is possible to separate rats with moderate and severe CHF in the rat coronary artery ligation model, the separation is not simply based on a specific EF value. This work may be useful in deciding whether there is a differential effect of new treatments for severe versus moderate CHF.

Enhanced expression of renal AQP2 and ENaC in rats with chronic heart failure: a role for renal nerves

Previously we have shown that increased expression of renal epithelial sodium channels (ENaC) subunits may contribute to the renal sodium and water retention observed during chronic heart failure (CHF). The goal of this study was to examine whether renal denervation (RDN) changes the expression of aquaporin 2 (AQP2) and two major renal sodium transporters ENaC and sodium‐hydrogen exchanger‐3 proteins (NHE3)] in rats with CHF. CHF was produced by left coronary artery ligation in rats. Four weeks after ligation surgery, bilateral RDN were performed. Western blot analysis indicated that RDN (one week later) significantly reduced enhanced protein levels of AQP2 (1.30±0.20 vs. 0.33±0.09, P&lt;0.05), alpha‐ENaC (0.43±0.09 vs. 0.25±0.06, P&lt;0.05), beta‐ENaC (0.11±0.03 vs. 0.05 ± 0.01, P&lt;0.05) and gamma‐ENaC (0.89±0.15 vs. 0.44±0.09, P&lt;0.05) subunits in the renal cortex of CHF rats compared to the CHF non‐denervated group. RDN had no significant effects on the protein expression of kidney NHE3 in both sham and CHF rats. These findings suggest a critical role for renal nerves in the enhanced expression of AQP2 and ENaC and subsequent pathophysiology of renal water and sodium retention associated with CHF.Support or Funding InformationSupported by NIH grants HL124104 and HL62222

DONEPEZIL HYDROCHLORIDE MITIGATES CONSEQUENCES OF ACUTE MYOCARDIAL INFARCTION IN MALE ALBINO RATS

Background Cholinesterase inhibitors are used for symptomatic treatment of mild to moderate Alzheimer’s disease. These drugs have vagomimetic and anti-inflammatory properties that could be of interest also with respect to cardiovascular diseases. Aim The aim of the present work is to assess effects of pretreatment with donepezil hydrochloride, one of cholinesterase inhibitors, on acute myocardial infarction induced by coronary artery ligation in rats. Methods Rats were randomly divided into control, sham-operated, untreated-myocardial infarction, and donepezil hydrochloride-pretreated myocardial infarction groups. Donepezil hydrochloride was administered orally, 1mg/kg/day, for six days then acute myocardial infarction was induced in 6th day by ligation of the left anterior descending coronary artery. ECG and blood pressure were recorded. Triphenyltetrazolium chloride (TTC) stained ventricular slices were examined. The plasma levels of tumor necrosis factor-α (TNF-α) and cardiac troponin I (cTnI) were assessed. Catalase activity and glutathione levels in the myocardium were determined. Results Coronary artery ligation increased T-wave voltage with appearance of pathological Q-wave, tachycardia, decreased mean arterial pressure and pale areas (infarcts) in TTC-stained ventricular slices. The plasma levels of TNF-α and cTnI were increased while the myocardial catalase activity and glutathione levels were decreased. In donepezil hydrochloride-pretreated group T-wave voltage and heart rate were decreased and pathological Q-wave disappeared with decrements in infarct size and plasma levels of TNF-α as well as cTnI, while catalase activity and glutathione levels were increased in relation to untreated myocardial infarction group. Conclusion Pretreatment with donepezil hydrochloride decreased myocardial infarct size. This effect could be related to its negative chronotropic, anti-inflammatory, and antioxidant actions.