Congestive Heart Failure Rats Research Articles

Role of ERK and NF-KB pathway in neurally mediated enhanced expression and traffcking of SGLT2 in congestive heart failure

Congestive heart failure (CHF) is characterized by the activation of neurohumoral systems concomitant with avid fluid retention. Recently we showed enhanced expression of sodium-glucose cotransporter 2 (SGLT2) in rats with CHF. However, the exact molecular mechanism linking enhanced sympathetic tone and enhanced expression and translocation of SGLT2 in CHF is not clear. The objective of this study was to investigate the role of enhanced sympathetic tone on the expression and traffcking of SGLT2 via activation of protein kinase A (PKA), extracellular signal-regulated kinases (ERK), and nuclear factor kappa B (NF-KB) in the renal cortex of CHF rats. Male Sprague Dawley rats were subjected to either the left coronary artery ligation for the CHF group or Sham surgery. Four weeks after surgery, expression of protein levels (PKA, ERK and NF-KB) were assessed by Western blotting, whereas the location of SGLT2 expression was determined by immunohistological and immunofluorescent staining in the cortical region of kidneys from Sham and CHF rats. Effect of exogenous norepinephrine (NE) (10μM for 24hrs) on expression and traffcking of SGLT2, phosphorylation of ERK and NF-KB in HK2 cells were examined in an in vitro model. Expression of SGLT2 was significantly enhanced in the renal cortex of rats with CHF versus Sham (0.83±0.06 vs. 0.58±0.02). Also, the translocation of SGLT2 was significantly enhanced towards the membrane in CHF rats (0.92±0.11 vs. 0.33±0.07). Phosphorylation of PKA (0.05±0.01 vs. 0.01±0.01), ERK (0.32±0.02 vs. 0.23±0.02) and NF-KB (0.71±0.14 vs. 0.08±0.06) were significantly enhanced in CHF compared to Sham. NE treatment significantly increased expression of SGLT2 (0.26±0.03 vs. 0.15±0.02), traffcking of SGLT2 (0.45 ± 0.09 vs. 0.15 ± 0.03) towards membrane, phosphorylation of ERK (0.38±0.05 vs. 0.14±0.02) and NF-KB (0.61±0.08 vs. 0.17±0.07) in HK2 cells. Thus, NE treatment enhanced the phosphorylation of ERK, NF-kB as well as traffcking of SGLT2. Immunohistological and immunofluorescent staining demonstrated increased expression of SGLT2 in the kidneys of rats with CHF. Similar results were observed in immunofluorescent staining of human kidney cells treated with NE. In conclusion, these findings indicate that NE activates ERK and NF-KB pathways which leads to enhanced traffcking and overexpression of SGLT2 in CHF. These results provide a molecular link between enhanced sympathetic tone, ERK and NF-KB pathway and the traffcking of SGLT2 to the luminal membrane of renal proximal tubular cells and consequent increase in sodium retention in rats with CHF. This study was funded by NIH R01-DK-129311. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of Angiotensin 1-7 and Mas Receptor Agonist on Renal System in a Rat Model of Heart Failure.

Congestive heart failure (CHF) is often associated with impaired kidney function. Over- activation of the renin-angiotensin-aldosterone system (RAAS) contributes to avid salt/water retention and cardiac hypertrophy in CHF. While the deleterious effects of angiotensin II (Ang II) in CHF are well established, the biological actions of angiotensin 1-7 (Ang 1-7) are not fully characterized. In this study, we assessed the acute effects of Ang 1-7 (0.3, 3, 30 and 300 ng/kg/min, IV) on urinary flow (UF), urinary Na+ excretion (UNaV), glomerular filtration rate (GFR) and renal plasma flow )RPF) in rats with CHF induced by the placement of aortocaval fistula. Additionally, the chronic effects of Ang 1-7 (24 µg/kg/h, via intra-peritoneally implanted osmotic minipumps) on kidney function, cardiac hypertrophy and neurohormonal status were studied. Acute infusion of either Ang 1-7 or its agonist, AVE 0991, into sham controls, but not CHF rats, increased UF, UNaV, GFR, RPF and urinary cGMP. In the chronic protocols, untreated CHF rats displayed lower cumulative UF and UNaV than their sham controls. Chronic administration of Ang 1-7 and AVE 0991 exerted significant diuretic, natriuretic and kaliuretic effects in CHF rats, but not in sham controls. Serum creatinine and aldosterone levels were significantly higher in vehicle-treated CHF rats as compared with controls. Treatment with Ang 1-7 and AVE 0991 reduced these parameters to comparable levels observed in sham controls. Notably, chronic administration of Ang 1-7 to CHF rats reduced cardiac hypertrophy. In conclusion, Ang 1-7 exerts beneficial renal and cardiac effects in rats with CHF. Thus, we postulate that ACE2/Ang 1-7 axis represents a compensatory response to over-activity of ACE/AngII/AT1R system characterizing CHF and suggest that Ang 1-7 may be a potential therapeutic agent in this disease state.

Quaternary amines exert anti-myocardial ischemia effects via regulation of energy metabolism and oxygen free radicals in myocardial cells in acute myocardial infarction rats

Purpose: To investigate the effect of quaternary amines on myocardial cells of a rat model of cardiac arrest, with respect to energy generation potential and oxygen free radicals.
 Methods: Forty-five Sprague-Dawley (SD) rats were assigned to sham, model and quaternary amine groups (each with 15 rats). After their corresponding treatments, lectrocardiogram (ECG) monitoring of the rats in the three groups at various time periods was carried out. Serum levels of myocardial enzymes, thromboxane B2 (TXB2), prostacyclin I2 (PGI2), serum carbon monoxide (CO), and changes in endothelial carbon monoxide synthase (eNOS) and endothelin (ET), were determined.
 Results: The levels of NO and eNOS were significantly reduced in model rats, relative to sham operation rats, while ET was significantly elevated in sham rats (p < 0.05). There were higher levels of NO and eNOS in the quaternary amine group than in model rats, but ET was higher in quaternary amine group than in model rats. Thromboxane B2 (TXB2) concentration was higher in model rats than in sham rats (p < 0.05). While PGI2 was markedly lower in quaternary group than in sham operation rats. TXB2 was lower in the quaternary amine group than in model rats, while PGI2 was significantly higher in quaternary amine group, relative to model rats (p < 0.05).
 Conclusion: Quaternary amines exert anti-myocardial effects by regulating energy metabolism and oxygen free radicals in myocardial cells of congestive heart failure rats, and thus are potentially useful for the management of acute myocardial infarction.
 Keywords: Quaternary amine; Acute myocardial infarction; Electrocardiogram; Serum myocardial enzymes; Myocardial cells

Intraventricular pressure gradient: a promising tool to predict the post-infarction chronic congestive heart failure in rats

Abstract Funding Acknowledgements Type of funding sources: None. Background/Introduction: Congestive heart failure (CHF), the main reason for morbidity and mortality, is considered a serious consequence of myocardial infarction (MI). The use of left ventricular end-diastolic pressure (LVEDP) as a chief indicator of CHF becomes limited because of the possible impairment of cardiac function and induced aortic valve damage during its recording. Echocardiography is the gold standard approach to diagnose structural myocardial dysfunction. However, its ability to predict chronic CHF following MI is still limited. Recently, intraventricular pressure gradient (IVPG) was presented as a non-invasive, highly sensitive preload-independent diastolic function parameter to assess cardiac function, especially during cardiomyopathy. However, there have not been any investigations demonstrating the feasibility of IVPG in the evaluation of post-infarction chronic CHF. Purpose This study aimed to investigate the utility of IVPG to assess the heart function in a rat model with chronic CHF following MI with evaluating its capacity to predict these changes. Methods Fifty male rats were included. MI was induced via ligation of the left anterior descending artery (LAD) at the level of the atrioventricular junction (MI animals, n = 35). Sham animals were subjected to the same left thoracotomy procedure without LAD ligation (Sham animals, n = 15). Transthoracic conventional echocardiography and colour M-mode echocardiography (CMME) for IVPG were performed in all animals 6 months post-surgery. The next day, animals were anesthetized, ventilated, and euthanized after the recording of hemodynamics. The heart weight, and lung and liver wet-to-dry weight ratios were recorded. J-tree cluster-analysis was performed based on ten echocardiographic variables indicative of CHF. Results Based on the cluster analysis, animals were joined into two clusters; CHF+ (n = 22) and named MI/HF+, and CHF- (n = 28) that was joined from sham (n = 15), and MI/HF- (n = 13). MI/HF+ presented the most severe anatomical and echocardiographic changes indicative of CHF with significant reduction of all IVPG indices and impairment of the hemodynamics. The IVPG indices were significantly (P< 0.0001) correlated with the anatomical and echocardiographic findings, LVDP, LVEDP, HR, -dP/dtmin, and Tau. Meanwhile, LVSP was only significantly correlated with apical IVPG (R = 0.677, P = 0.022). dP/dtmax was significantly correlated with total IVPG, basal IVPG, and apical IVPG (R = 0.797, P = 0.017, R = 0.724, P = 0.003, and R = 0.652, P = 0.026 ; respectively). Moreover, total, basal, mid-to-apical, mid-, and apical IVPG were significant (P< 0.0001) predictors of chronic CHF following MI. Conclusion Compared to the structural, and functional indices of conventional echocardiography, IVPG derived from CMME could provide a substantial non-invasive tool to diagnose and predict CHF after long-term MI.

Abstract 9961: Combination Therapy with Selective Endothelin Type A Receptor Blockade and Angiotensin-converting Enzyme Blockade Improves Survival of Congestive Heart Failure Similarly to Both Monotherapies: Study in Ren-2 Transgenic Hypertensive Rats with Aorto-Caval Fistula

Introduction: New therapeutic strategies for congestive heart failure (CHF) are needed, and the current knowledge, including our previous studies, suggests that targeting the endothelin (ET) system could be a promising approach. Hypothesis: Chronic selective blockade of ET type A (ETA) receptors combined with angiotensin-converting enzyme inhibitor (ACEi) would attenuate the course of CHF induced by volume overload achieved by the creation of the aorto-caval fistula (ACF). Methods: ACF was created in Ren-2 transgenic rats (TGR), a model of angiotensin II-dependent hypertension, at the animal age of 8 weeks. Two weeks later the animals were randomly divided into four groups and the therapy began: chronic selective blockade of ETA receptors with atrasentan (ETA block.) (5 mg.kg-1.day-1 in drinking water, n = 31), angiotensin-converting enzyme inhibitor (ACEi) (trandolapril, 2 mg.L-1 in drinking water, n = 32), a combination of atrasentan plus trandolapril (ETA block. + ACEi) ( 5 mg.kg-1.day-1 + 2 mg.L-1 in drinking water, n = 31) or placebo (n = 30). Sham-operated TGR represented a control group (n = 8). The follow-up period was 20 weeks. GraphPad Prism 7 was used for statistical analysis with a log-rank (Mantel-Cox) test to analyze survival data. Results: All sham-operated rats survived till the end of the study. Contrary, all untreated CHF rats died by week 12. The treatment with the ETA block. or with ACEi similarly improved the survival rate, and the final rate was 45 % in ETA block. group (p < 0,01) and 62 % in ACEi group (p < 0,01), the combinational therapy (ETA block. + ACEi) improved survival rate over placebo (52 %, p < 0,01) but not compared with both monotherapies. Conclusions: Our present results suggest that in ACF TGR, the combination treatment with ETA block. and ACEi did not markedly attenuate CHF-dependent mortality over both monotherapies. Thus, more preclinical research needs to be done to deeper understand the endothelin system in CHF.

Effect of Atractylodes macrocephala extract on chronic heart failure in rats

Purpose: To investigate the effect of Atractylodes macrocephala extract (AME) on oxidative stress and hemodynamics in chronic congestive heart failure (CHF) rats.
 Methods: After Sprague Dawley (SD) rats were successfully establised into CHF, they were randomly divided into normal control group, negative control group, captopril group, as well as 1.4, 2.8 and 5.6 g/kg of AME groups, and treated with drugs for 4 weeks. Hemodynamic function, whole heart weight index, blood creatinine kinase (CK), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), nitric oxide synthase (NOS) were measured.
 Results: Compared with the normal control group, arterial systolic pressure (SBP)(83.12 ± 16.21 mmHg), diastolic pressure (DBP, (75.16 ± 20.18 mmHg), mean arterial pressure (MAP 76.32 ± 13.43 mmHg), heart rate (HR 353.25 ± 36.34 beats/min), left ventricular systolic peak (LVSP 101.24 ± 16.13 mmHg), and left ventricular pressure change rate (dp/dt max) significantly decreased (p < 0.05), while left ventricular end diastolic pressure (LVEDP (22.13 ± 1.57 mmHg), whole heart weight index (2.74 ± 0.16 mg/g), blood CK (0.93 ± 0.14 U/mL), MDA (19.13 ± 2.26 nmol/mL), NO (34.21 ± 3.16 umol/L), and NOS (42.13 ± 3.24 U/mL) increased significantly increased in the negative control group (p < 0.05). High dose AME significantly improved hemodynamic function, lowered MDA (8.75 ± 2.09 nmol/mL) and NO (22.14 ± 3.27 umol/L) levels (p < 0.05), and also decreased CK (0.57 ± 0.31 U/mL) and NOS (24.24 ± 3.38 U/mL) in CHF rats (p < 0.05).
 Conclusion: AME significantly improve adriamycin-induced chronic congestive heart failure in rats, which could be used for the therapeutic management of chronic congestive heart failure in future.

Ophiopogon japonicas (Linn. f.) Ker-Gawl. extract ameliorates chronic heart failure in rats

Purpose: To investigate the effect of Ophiopogon japonicas (Linn. f.) Ker-Gawl. extract (OJKE) on oxidative stress and hemodynamics in chronic congestive heart failure (CHF) rats.
 Methods: The rats were modelled to congestive heart failure (except normal group) , and then randomly divided into normal control group, model (untreated) group, captopril group, high-dose, middle-dose and low-dose of OJKE groups. They were treated for 4 weeks as appropriate for each group. At the end of treatment, the hemodynamic function, whole heart weight index, and blood creatinine kinase (CK), as well as superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), nitricoxide synthase (NOS) were determined.
 Results: Compared with the normal control group, arterial systolic pressure (SBP), diastolic pressure (DBP), mean arterial pressure (MAP), heart rate (HR), left ventricular systolic peak (LVSP), and left ventricular pressure change rate (dp/dt max) significantly decreased (p < 0.05), while left ventricular end diastolic pressure (LVEDP), whole heart weight index, blood CK, MDA, NO, NOS significantly increased in the untreated group (p < 0.05). A high dose of OJKE significantly improved hemodynamic function, lowered MDA (8.33 ± 2.12 nmol/mL) and NO (20.58 ± 3.53 umol/L) levels (p < 0.05), and also decreased CK (0.53±0.37 U/mL) and NOS (22.46±3.29 U/mL) in CHF rats (p < 0.05).
 Conclusion: OJKE improved adriamycin-induced chronic congestive heart failure in rats significantly.

Identification, localization and expression of NHE isoforms in the alveolar epithelial cells.

Na+/H+ exchangers (NHEs), encoded by Solute Carrier 9A (SLC9A) genes in human, are ubiquitous integral membrane ion transporters that mediate the electroneutral exchange of H+ with Na+ or K+. NHEs, found in the kidney and intestine, play a major role in the process of fluid reabsorption together via Na+,K+-ATPase pump and Na+ channels. Nevertheless, the expression pattern of NHE in the lung and its role in alveolar fluid homeostasis has not been addressed. Therefore, we aimed to examine the expression of NHE specific isoforms in alveolar epithelial cells (AECs), and assess their role in congestive heart failure (CHF). Three NHE isoforms were identified in AEC and A549 cell line, at the level of protein and mRNA; NHE1, NHE2 and mainly NHE8, the latter was shown to be localized in the apical membrane of AEC. Treating A549 cells with angiotensin (Ang) II for 3, 5 and 24 hours displayed a significant reduction in NHE8 protein abundance. Moreover, the abundance of NHE8 protein was downregulated in A549 cells that were treated overnight with Ang II. NHE8 abundance in whole lung lysate was increased in rats with 1-week CHF compared to sham operated rats. However, lower abundance of NHE8 was observed in 4-week CHF group. In conclusion, we herein show for the first time, the expression of a novel NHE isoform in AEC, namely NHE8. Notably, Ang II decreased NHE8 protein levels. Moreover, NHE8 was distinctly affected in CHF rats, probably depending on the severity of the heart failure.

DIFFERENT FORMS OF AFFERENT NERVE INPUT IN CARDIAC AND RENAL DISEASE IN RATS?

Objective: Afferent nerve pathways form kidney and heart are said to control sympathetic renal nerve activity. In a renal disease model the responsiveness of afferent renal nerve units was shifted from units with highly active primary neurons (tonic response pattern) to units with neurons of very low activity upon stimulation (phasic response pattern). Afferent renal nerve activity was likely decreased. Likewise, afferent vagal nerve activity in congestive heart failure (CHF) had a lower frequency at saturation than controls. Hence we wanted to test the hypothesis that CHF the vagal afferent nerve pathway consists of a decreased number of highly active tonic sensory neurons in the nodose ganglion. Design and method: CHF was induced by coronary artery ligature, nephropathy by injections of an anti Thy1.1 antibody (OX7, 1.2 mg/kg). After a respective time (CHF 21 days, nephropathy 7 days after induction) nodose ganglion neurons with cardiac vagal afferents from CHF rats or neurons form dorsal root ganglia with renal afferents from rats with nephropathy were cultured. Current clamp was used to characterize neurons as tonic, i.e. sustained action potential (AP) firing or phasict, i.e. <5 APs upon current injection. More than 100 neurons were investigated. Results: In CHF rats, the number of neurons with a tonic response pattern did not differ from controls (64% vs. 70 %, ns). However, tonic cardiac neurons from CHF rats exhibited an increased production of action potentials compared (24.4+/-5.0 vs. 14.7+/-1.8 APs/10 s; p < 0.05; mean+/-SEM). In nephropathic rats, the number of neurons with a tonic response pattern decreased significantly (43% vs. 64 %, p < 0.05), but there was no difference in action potential production between groups. Conclusions: In congestive heart failure the number of afferent neurons with a tonic response pattern was not significantly altered. However, the action potential production of these neurons even significantly increased upon stimulation. Hence, in congestive heart failure vagal afferent neurons increase their sensitivity in the presence of impaired intracardiac receptors whereas in renal disease the responsiveness of the first part of the afferent pathway is impaired as a whole.

AT II Receptor Blockade and Renal Denervation: Different Interventions with Comparable Renal Effects?

Background: Angiotensin II (Ang II) and the renal sympathetic nervous system exert a strong influence on renal sodium and water excretion. We tested the hypothesis that already low doses of an Ang II inhibitor (candesartan) will result in similar effects on tubular sodium and water reabsorption in congestive heart failure (CHF) as seen after renal denervation (DNX). Methods: Measurement of arterial blood pressure, heart rate (HR), renal sympathetic nerve activity (RSNA), glomerular filtration rate (GFR), renal plasma flow (RPF), urine volume, and urinary sodium. To assess neural control of volume homeostasis, 21 days after the induction of CHF via myocardial infarction rats underwent volume expansion (0.9% NaCL; 10% body weight) to decrease RSNA. CHF rat and controls with or without DNX or pretreated with the Ang II type-1 receptor antagonist candesartan (0.5 ug i.v.) were studied. Results: CHF rats excreted only 68 + 10.2% of the volume load (10% body weight) in 90 min. CHF rats pretreated with candesartan or after DNX excreted from 92 to 103% like controls. Decreases of RSNA induced by volume expansion were impaired in CHF rats but unaffected by candesartan pointing to an intrarenal drug effect. GFR and RPF were not significantly different in controls or CHF. Conclusion: The prominent function of increased RSNA – retaining salt and water – could no longer be observed after renal Ang II receptor blockade in CHF rats.

Curative and Protective Effect of Salvia Officinalis Oil on Isoprenaline-Induced Congestive Heart Failure in Rats

Curative and Protective Effect of Salvia Officinalis Oil on Isoprenaline-Induced Congestive Heart Failure in Rats

Qiliqiangxin improves cardiac function and attenuates cardiac remodelling in doxorubicin-induced heart failure rats

Context Therapeutic doxorubicin administration is restricted as this anticancer drug may be cardiotoxic. The traditional Chinese medicine qiliqiangxin has been approved for clinical treatment of chronic heart failure. Objective To explore the protective effects and molecular mechanisms of qiliqiangxin on doxorubicin-induced congestive heart failure (CHF) in rats. Materials and methods A CHF rat model was established via intraperitoneal DOX injections (2.5 mg/kg/week) for 6 weeks. The rats were randomly assigned to control, CHF, CHF + QL (1.0 g/kg/d), or captopril (3.8 mg/kg/d) treatment groups (n = 10) for 4 weeks. MicroRNA sequencing elucidated the molecular mechanisms of qiliqiangxin on doxorubicin-induced CHF in rats. Results Unlike in the CHF group, QL significantly reduced Bax:Bcl-2 (2.05 ± 0.23 vs. 0.94 ± 0.09, p < 0.05) and the levels of collagen I (0.19 ± 0.02 vs. 0.15 ± 0.01, p < 0.05), collagen III (0.19 ± 0.02 vs. 0.14 ± 0.02, p < 0.05), TGF-β1 (5.28 ± 0.89 vs. 2.47 ± 0.51, p < 0.05), Smad3 (1.23 ± 0.12 vs. 0.78 ± 0.09, p < 0.05), MMP-2 (0.89 ± 0.01 vs. 0.53 ± 0.05, p < 0.05), and TIMP-2 (0.24 ± 0.03 vs. 0.44 ± 0.03, p < 0.05). QL also upregulated TGF-β3 (0.65 ± 0.06 vs. 0.96 ± 0.10, p < 0.05) and Smad7 (0.09 ± 0.01 vs. 0.19 ± 0.023, p < 0.05). Moreover, Smad3 was a target of miR-345-3p. Discussion and Conclusions The beneficial effects of QL on DOX-induced CHF in rats are mediated by reduction in myocardial fibrosis, promotion of TGF-β3/Smad7, and inhibition of TGF-β1/Smad3. QL may also modulate specific miRNAs. These results provide evidence that QL might be an effective treatment for DOX-induced CHF.

Augmented fear bradycardia in rats with heart failure.

In congestive heart failure (CHF), while resting parasympathetic activity becomes reduced, parasympathetically-mediated responses to stressors have not been described. This study aimed to (1) elucidate the effect of CHF on fear bradycardia, a parasympathetically-mediated response, and (2) examine if brain oxidative stress of CHF mediates fear bradycardia. White noise sound (WNS) exposure to conscious rats induced freezing behavior and elicited bradycardia. WNS exposure-elicited bradycardia was greater in rats with CHF than in controls. Superoxide dismutase mimetics administered in the lateral/ventrolateral midbrain periaqueductal gray (l/vlPAG), a region that contributes to the generation of fear bradycardia, had no effect on the bradycardia response in control and CHF rats. Dihydroethidium staining in situ showed that superoxide generation in the l/vlPAG of CHF rats was increased as compared to controls. These results demonstrate that CHF leads to the augmentation of fear bradycardia. Moreover, oxidative stress in the l/vlPAG of CHF unlikely mediates the augmented fear bradycardia.

Rosiglitazone treatment restores renal responsiveness to atrial natriuretic peptide in rats with congestive heart failure.

The thiazolidinedione (TZD) class of Peroxisome proliferator‐activated receptor gamma agonists has restricted clinical use for diabetes mellitus due to fluid retention and potential cardiovascular risks. These side effects are attributed in part to direct salt‐retaining effect of TZDs at the renal collecting duct. A recent study from our group revealed that prolonged rosiglitazone (RGZ) treatment caused no Na+/H2O retention or up‐regulation of Na+ transport‐linked channels/transporters in experimental congestive heart failure (CHF) induced by surgical aorto‐caval fistula (ACF). The present study examines the effects of RGZ on renal and cardiac responses to atrial natriuretic peptide (ANP), Acetylcholine (Ach) and S‐Nitroso‐N‐acetylpenicillamine (SNAP‐NO donor). Furthermore, we assessed the impact of RGZ on gene expression related to the ANP signalling pathway in animals with ACF. Rats subjected to ACF (or sham) were treated with either RGZ (30 mg/kg/day) or vehicle for 4 weeks. Cardiac chambers pressures and volumes were assessed invasively via Miller catheter. Kidney excretory and renal hemodynamic in response to ANP, Ach and SNAP were examined. Renal clearance along with cyclic guanosine monophosphate (cGMP), gene expression of renal CHF‐related genes and ANP signalling in the kidney were determined. RGZ‐treated CHF rats exhibited significant improvement in the natriuretic responses to ANP infusion. This ‘sensitization’ to ANP was not associated with increases in neither urinary cGMP nor in vitro cGMP production. However, RGZ caused down‐regulation of several genes in the renal cortex (Ace, Nos3 and Npr1) and up‐regulation of ACE2, Agtrla, Mme and Cftr along down‐regulation of Avpr2, Npr1,2, Nos3 and Pde3 in the medulla. In conclusion, CHF+RGZ rats exhibited significant enhancement in the natriuretic responses to ANP infusion, which are known to be blunted in CHF. This ‘sensitization’ to ANP is independent of cGMP signalling, yet may involve post‐cGMP signalling target genes such as ACE2, CFTR and V2 receptor. The possibility that TZD treatment in uncomplicated CHF may be less detrimental than thought before deserves additional investigations.

Animal model of left atrial thrombus in congestive heart failure in rats.

The aim of the present study was to develop and study a new model of left atrial thrombus (LAT) in rat with congestive heart failure (CHF). CHF was induced by aortic banding for 2 mo, followed by ischemia-reperfusion (I/R) and subsequent aortic debanding for 1 mo. Cardiac function and the presence of LAT were assessed by echocardiography. Masson's staining was performed for histological analysis. All CHF rats presented with significantly decreased cardiac function, fibrosis in remote myocardium, and pulmonary edema. The incidence rate of LAT was 18.8% in the rats. LAT was associated with severity of aortic constriction, aortic pressure gradient, aortic blood flow velocity, and pulmonary edema but not myocardial infarction or a degree of left ventricular depression. The progressive process of thrombogenesis was characterized by myocyte hypertrophy, fibrosis, and inflammation in the left atrial wall. Fibrin adhesion and clot formation were observed, whereas most LAT presented as a relatively hard "mass," likely attributable to significant fibrosis in the middle and outer layers. Some LAT mass showed focal necrosis as well as fibrin bulging. Most LAT occurred at the upper anterior wall of the left atrial appendage. Aortic debanding had no significant impact on large LATs (>5 mm2) that had formed, whereas small LATs (<5 mm2) regressed 1 mo after aortic release. LAT is found in a rat model of aortic banding plus I/R followed by aortic debanding. The model provides a platform to study molecular mechanisms and potential new pathways for LAT treatment. NEW & NOTEWORTHY It is critically important to have a rodent model to study the molecular mechanism of thrombogenesis in the left atrium. Left atrial thrombus (LAT) is not a simple fibrin clot like those seen in peripheral veins or arteries. Rather, LAT is a cellular mass that likely develops in conjunction with blood clotting. Studying this phenomenon will help us understand congestive heart failure and promote new therapies for LAT.

Increased Intra-abdominal Pressure Induces Acute Kidney Injury in an Experimental Model of Congestive Heart Failure

Congestive heart failure (CHF) entails a complex interaction between the heart and the kidney that represents a clinical entity called cardiorenal syndrome (CRS). One of the mechanisms underlying CRS includes increased intra-abdominal pressure (IAP). We examined the effect of elevated IAP on kidney function in rats with low- and high-output CHF. Rats with compensated and decompensated CHF induced by means of aortocaval fistula, rats with myocardial infraction (MI) induced by means of left anterior descending artery ligation, and sham control rats were subjected to either 10 or 14 mm Hg IAP. Urine flow (V), Na+ excretion (UNaV), glomerular filtration rate (GFR), and renal plasma flow (RPF) were determined. The effects of pretreatment with tadalafil (10 mg/kg orally for 4 days) on the adverse renal effects of IAP were examined in decompensated CHF and MI. Basal V and GFR were significantly lower in rats with decompensated CHF compared with sham control rats. Decompensated CHF rats and MI rats subjected to 10 and 14 mm Hg IAP exhibited more significant declines in V, UNaV, GFR and RPF than compensated and sham controls. Elevated IAP also induced tubular injury, as evidenced by significantly increased absolute urinary excretion of neutrophil gelatinase-associated lipocalin. In addition, in a nonquantitative histologic analysis, elevated IAP was associated with increase in necrosis and cell shedding to the tubule lumens, especially in the decompensated CHF subgroup. Pretreatment of decompensated CHF rats and MI rats with tadalafil ameliorated the adverse renal effects of high IAP. Elevated IAP contributes to kidney dysfunction in high- and low-cardiac output CHF. IAP induces both hemodynamic alterations and renal tubular dysfunction. These deleterious effects are potentially reversible and can be ameliorated with the use of phosphodiesterase-5 inhibition.

Eplerenone Reverses Cardiac Fibrosis via the Suppression of Tregs by Inhibition of Kv1.3 Channel.

Background: Fibroblast proliferation is a critical feature during heart failure development. Previous studies reported regulatory T-lymphocytes (Tregs)’ protective role against myocardial fibrosis. However, notably, Tregs also secrete fibrogenic cytokine TGF-β when activated. This study aimed to clarify the intriguing link between Tregs and fibrosis, the role of Tregs Kv1.3 potassium channel (regulating T-lymphocytes activation) in the fibrosis process, and how selective aldosterone receptor antagonist Eplerenone affects Tregs and fibrosis through its action on Kv1.3 channel.Methods and Results: After co-incubation with Tregs, cardiac fibroblast proliferation (CCK-8 assay) and levels of collagen I, III, and Matrix metalloproteinase2 (ELISA) significantly elevated. Cell viability assays, Kv1.3 channel mRNA (RT-qPCR), and protein expression (In-Cell Western Blotting) revealed Tregs were activated/proliferated when co-cultured with fibroblasts. Treg intracellular TGF-β level increased by 5.8-fold, far more than that of intracellular IL-10, extracellular TGF-β and IL-10 (ELISA). And 30 μM eplerenone suppressed Tregs proliferation by 82.77% and furthermore, suppressed intracellular TGF-β level to a significantly greater extent than that of intracellular IL-10, extracellular TGF-β and IL-10. Moreover, the Kv1.3 current (whole-cell patch clamp) of Tregs in congestive heart failure patients and rats (induced by coronary artery ligation and exhaustive exercise) elevated by >4-fold than that of healthy volunteers and control rats, whereas 30 μM eplerenone suppressed the current by >60% in control Tregs. In addition, docking calculations (AutoDock software 4.0 suite) showed eplerenone has higher H-bond energy with Kv1.3 channel than other selective blockers.Conclusion: Immuno-regulation in the late stage of CHF activates Tregs proliferation via the upregulation of Kv1.3 channels, which promotes cardiac fibrosis by primarily secreting TGF-β. Taken together, eplerenone’s high affinity to Kv1.3 channel enables it to antagonize the Kv1.3 channels directly to suppress Tregs proliferation, which in turn may play an immuno-regulatory role during CHF.

Abstract 373: An Animal Model of Left Atrial Thrombus

Left atrial thrombus (LAT) is a common funding of some cardiovascular diseases such as congestive heart failure (CHF), atrial fibrillation and myocardial injury. There is no proper animal model of LAT to date. The present study reports a model of congestive heart failure in rats that is characterized by LAT. Methods: LAT were induced by aortic banding 2 months plus 30 minutes ischemia and reperfusion 1 m followed with aortic de-banding 1 m in rats. Cardiac function and blood flow velocity were assessed by echocardiography. Masson’s stainings were conducted for histology. Results: congestive heart failure (CHF) in rats with LAT showed significant dilatation in left atrium (CHF = 56 ± 18 mm, N = 7, Control = 25 ± 6 mm, N = 10), significant decrease in left appendage blood flow velocity (CHF = 4.20 ± 0.09, Control = 0.21 ± 0.05 m/s) and mitral valve blood velocity (CHF = 0.76 ± 0.09 m/s, Control = 1.01 ± 0.04 m/s). Histology data showed that mature LAT had a complete membrane; the thrombus was characterized by significant fibrosis in middle and out layers. The outer layer of thrombus had microvessels and the cells were nucleated. The central part of the thrombus had very little fibrosis and showed necrosis. Small thrombus (0.05 - 0.1 mm) had a base from which the blood clot grew. Atrial neo-intimal fibrosis plays an important role in the formation of the base of microembolization. However, in some cases, micro-thrombi (&lt;0.01 mm) showed no fibrotic base. Conclusion: left atrial thrombus results from blood flow congestion. However, it is still not clear whether the thrombus is due to vascular proliferation from the atrial wall or through adhesion of coagulation fibers to the atrial wall. Figure. A. echocardiographic imaging. B. left atrial area . C. mitral valve blood velocity. D. echocardiography of left atrial blood velocity. E. left atrial blood flow velocity. F. regular imaging of LAT. G. cross sectional imaging. H. small LAT. I. endometrial fibrosis. J. micro thrombus. K. coagulation fiber.

Effect of Zhen-wu decoction on chronic heart failure in rats

Purpose: To investigate the effect of Zhen-wu decoction (ZWD) on oxidative stress and hemodynamics in chronic congestive heart failure (CHF) rats.Methods: After Sprague Dawley (SD) rats were successfully prepared into CHF, they were randomly divided into normal control group, model (untreated CHF) group, captopril group, high-dose, middledose and low-dose of ZWD groups, and were treated with drugs for 4 weeks respectively. At the end of the experiment, hemodynamic function, whole heart weight index, blood creatinine kinase (CK), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO) and nitric oxide synthase (NOS) were determined.Results: Compared with normal control group, ZWD group showed decreased arterial systolic pressure (SBP, 89.16 ± 17.27 mmHg), diastolic pressure (DBP, 72.54 ± 22.36 mmHg), mean arterial pressure (MAP, 72.64 ± 11.87 mmHg), heart rate (HR, 368.25 ± 39.12 beats/min), left ventricular systolic peak (LVSP, 105.27 ± 15.23 mmHg), and left ventricular pressure change rate (dp/dt max) (p &lt; 0.05), while left ventricular end diastolic pressure (LVEDP) (19.52 ± 1.89 mmHg), whole heart weight index (2.74 ± 0.16 mg/g), blood CK (0.98 ± 0.16 U/mL), MDA (17.28 ± 2.94 nmol/mL), NO (36.35 ± 3.27 umol/L), NOS (39.89 ± 3.56 U/mL) significantly increased (p &lt; 0.05). High dose of ZWD significantly improved hemodynamic function, lowered MDA (8.85 ± 2.14 nmol/mL) and NO (24.25 ± 3.21 umol/L) levels (p &lt; 0.05), and also decreased CK (0.58 ± 0.37 U/mL) and NOS (26.12 ± 3.87 U/mL) in CHF rats (p &lt; 0.05).Conclusion: ZWD improves adriamycin-induced chronic congestive heart failure in rats significantly, and therefore has potential to be developed for the management of chronic congestive heart failure.Keywords: Zhen-wu decoction, Chronic heart failure, Hemodynamic function, Oxidative stress

Coronary capillary blood flow in a rat model of congestive heart failure.

The morphology of CHF capillaries is significantly disordered and tortuous compared with control (CSI: 0.35 ± 0.02 for 61 images from 7 CHF rats; 0.58 ± 0.02 for 32 images from 7 control rats; P < 0.01). Estimated capillary resistance in CHF is elevated by 173% relative to control, while blood flow rate and blood velocity are 56 and 43% slower than control. Capillary resistance increased 67% due to the significantly narrower capillary diameter in CHF, while it increased an additional 105% due to tortuosity. The significant structural abnormalities of CHF coronary capillaries may drastically stagnate hemodynamics in myocardium and increase resistance to blood flow. This could play a role in the development of CHF. NEW & NOTEWORTHY In the present study, coronary capillary tortuosity was measured by applying Matrix Laboratory software to scanning electron microscope images of capillaries in a rat model of congestive heart failure. Stagnant blood flow in coronary capillaries may play a role in the development of congestive heart failure. The application of computer modeling to histological and physiological data to characterize the hemodynamics of coronary microcirculation is a new area of study.