Left Coronary Artery Ligation Research Articles

The Different Therapeutic Effects of Traditional Chinese Medicine Shensong Yangxin Capsule and Salubrinal in High-intensity Exercise-induced Heart Failure in Rats with Acute Myocardial Infarction.

Currently, endoplasmic reticulum stress is studied utilizing a dephosphorylation inhibitor (Sal). The traditional Chinese patent medicine and simple formulation Shensong Yangxin Capsule is a commonly used medication for the treatment of arrhythmia. However, the efficacy and underlying mechanism of the capsule in treating post-ischemic heart failure in myocardial tissue have not yet been investigated. The therapeutic effects and the underlying mechanism of the Shensong Yangxin Capsule (SSYX) and the dephosphorylation inhibitor Salubrinal (Sal) on heart failure (HF) induced by high-intensity exercise in rats with acute myocardial infarction (AMI) were investigated. Male infants of 8 weeks Spragge-Dawley (SD) rats were randomly assigned to one of four groups: sham surgery group, AMI+placebo group, AMI+Shensong Yangxin Capsule group (AMI+SSYX), and AMI+Sal administration group. Rats' myocardial infarction was induced by left coronary artery ligation. Rats were subjected to a 3-week high-intensity exercise program to simulate heart failure after 7 days of postoperative rest. After the fourth postoperative week, echocardiography was applied to determine the left ventricular ejection fraction (LVEF), left ventricular fractional shortening (LVFS), and left ventricular systolic volume (LVESV) in each group. HE and TUNEL labeling were employed to examine the morphology of cardiac cells and measure the percentage of apoptosis in each group; Western blotting was applied to detect the cardiomyocyte apoptosis-related proteins p-JNK, p-P38, and NOX2, while ELISA was used to detect glutathione(GSH), malondialdehyde (MDA), and superoxide dismutase SOD in serum. Following a 4-week drug intervention:(1)LVFS and LVEF in the AMI+placebo group were statistically significantly reduced, while LVESV were significantly higher, compared to those in the sham surgery group (P<0.05); The AMI+SSYX group performed statistically significantly better than the AMI+placebo group(P<0.05). (2) The myocardial cells in the AMI+placebo group exhibited significant swelling and inflammatory cell infiltration; the myocardial cells in the AMI+SSYX group and AMI+Sal group displayed mild swelling and minimal inflammatory cell infiltration; the AMI+SSYX group's myocardial cell morphology was superior to that of the AMI+Sal group; (3) The apoptosis rate of the AMI+placebo group was around 95%, greater than that of the sham surgery group (2.55%). The apoptosis rate of the AMI+SSYX group is approximately 21%, while the apoptosis rate of the AMI+Sal group is about 43%. (4) In the AMI+placebo group, p-JNK, p-P38, and NOX2 protein expression dramatically increased compared to the sham surgery group. The expression of p-P38, NOX2, and p-JNK/t-JNK was considerably reduced in the AMI+Shensong group and AMI+Sal group， compared to the AMI+placebo group. (P<0.01)The AMI+SSYX group's result is superior to that of the AMI+Sal group. (5) Compared to the sham surgery group, the serum levels of SOD and GSH were significantly lower, and MDA was significantly higher in the AMI+placebo group. Compared to the AMI+placebo group, the serum levels of SOD and GSH were significantly higher, and MDA was significantly lower in the AMI+SSYX group and the AMI+Sal group. (P<0.05) Conclusion: In rats with acute myocardial infarction in high-intensity exercise-induced heart failure, Shensong Yangxin Capsule dramatically reduces myocardial cell death and cardiac dysfunction. SSYX has a shorter course of treatment and a better therapeutic effect than Sal.

Cardiomyocyte-specific overexpression of GPR22 ameliorates cardiac injury in mice with acute myocardial infarction

BackgroundThe activation of G protein-coupled receptors (GPCR) signaling by external stimuli has been implicated in inducing cardiac stress and stress responses. GPR22 is an orphan GPCR expressed in brains and hearts, while its expression level is associated with cardiovascular damage in diabetes. Previous studies have suggested a protective role of GPR22 in mechanical cardiac stress, as loss of its expression increases susceptibility to heart failure post-ventricular pressure overload. However, the involvement and underlying signaling of GPR22 in cardiac stress response to ischemic stress remains unexplored.MethodsIn this study, we used cultured cells and a transgenic mouse model with cardiomyocyte-specific GPR22 overexpression to investigate the impact of ischemic stress on GPR22 expression and to elucidate its role in myocardial ischemic injury. Acute myocardial infarction (AMI) was induced by left coronary artery ligation in eight-week-old male GPR22 transgenic mice, followed by histopathological and biochemical examination four weeks post-AMI induction.ResultsGPR22 expression in H9C2 and RL-14 cells, two cardiomyocyte cell lines, was decreased by cobalt chloride (CoCl2) treatment. Similarly, reduced expression of myocardial GPR22 was observed in mice with AMI. Histopathological examinations revealed a protective effect of GPR22 overexpression in attenuating myocardial infarction in mice with AMI. Furthermore, myocardial levels of Bcl-2 and activation of PI3K-Akt signaling were downregulated by ischemic stress and upregulated by GPR22 overexpression. Conversely, the expression levels of caspase-3 and phosphorylated ERK1/2 in the infarcted myocardium were downregulated with GPR22 overexpression.ConclusionMyocardial ischemic stress downregulates cardiac expression of GPR22, whereas overexpression of GPR22 in cardiomyocytes upregulates Akt signaling, downregulates ERK activation, and mitigates ischemia-induced myocardial injury.

Dan-Lou tablets reduce inflammatory response by inhibiting the activation of NLRP3 inflammasome for coronary heart disease

BackgroundThe activation of the NLRP3 inflammasome has recently been revealed as a novel pathological mechanism of coronary heart disease (CHD). The Dan-Lou tablets (DLT) is widely used in the clinical treatment of CHD and prescription characterized by multi-component and multi-target regulation. However, the anti-inflammatory mechanism of DLT in the treatment of CHD remains unclear. PurposeThis study aimed to evaluate the effect of DLT in the treatment of CHD on the priming and activation of the NLRP3 inflammasome and to investigate the underlying anti-inflammatory mechanisms. MethodsFirst, CHD rats model were established by a high-fat diet combined with left anterior coronary artery ligation (LADCA) followed by DLT intervention. The therapeutic effect of DLT was evaluated according to cardiac function, lipid level, and cardiac histopathology. Next, data-independent acquisition (DIA) proteomics was used to identify the key differential proteins of DLT intervention in CHD rats, and bioinformatics analysis was performed. Finally, the differentially expressed proteins in the NOD-like signaling pathway were verified based on bioinformatics results, and the priming and activation steps of the NLRP3 inflammasome were detected. ResultsIn this study, a high-fat diet combined with LADCA was utilized to generate a CHD model, and DLT alleviated myocardial ischemia injury by inhibiting lipid deposition and inflammatory response. Proteomic studies observed that the RNF31, TXN2, and GBP2 of the NOD-like receptor signaling pathway were verified as the key targets of DLT in inhibiting myocardial injury in CHD rats. Furthermore, DLT in the treatment of CHD rats may function through the downregulation of P2X7R expression, thereby interfering with the priming (TLR4/MyD88/NF-κB) and activation (NLRP3/ASC/Caspase-1) of the NLRP3 inflammasome regulated by HSP90, and may then reduce the release of the IL-1β and IL-18 inflammatory factors to play an anti-myocardial injury effect. ConclusionOur findings elucidate a novel mechanism of DLT and provide some new drug evaluation targets and therapeutic strategies for CHD. This study innovatively proposed that DLT further exerts an anti-myocardial injury effect by inhibiting P2X7R expression, thereby interfering with the priming (TLR4/MyD88/NF-κB) and activation (NLRP3/ASC/Caspase-1) of the NLRP3 inflammasome regulated by HSP90, and then downregulates the release of the IL-1β and IL-18 inflammatory factors.

Physiopathological Mechanisms of Type 1 Cardiorenal Syndrome Induced by Acute Myocardial Infarction

Objectives: Cardiovascular diseases are the leading global cause of mortality. Approximately 20 to 31% of acute myocardial infarction (AMI) cases progress to renal dysfunction, indicating concurrent cardiac and renal alterations, characterizing Cardiorenal Syndrome Type 1 (CS1). Therefore, this study evaluates the CS1 onset and progression three days after AMI by examining renal and cardiac function and their inflammatory responses. The study hypothesizes that inflammatory mediators are a key component contributing significantly to the onset and progression of CS1 pathophysiology. Methods: Male Sprague-Dawley rats (250-300g) were divided into AMI-SHAM (undergoing sham surgery for AMI) and AMI (left coronary artery ligation) groups. Samples were collected three days post-AMI from blood, urine, heart, and renal tissues. Assessments included osmolality (plasma and urine), creatinine (plasma and urine), glomerular filtration rate (GFR), and tissue cytokine levels. Left ventricular end-diastolic pressure (LVEDP) represented cardiac function. Results are presented as mean ± standard error. Results: LVEDP measurements (mmHg) demonstrated similar results from SHAM (5.89 ± 0.61, n=14) and AMI groups (6.38 ± 0.43, n=6). Tumor Necrosis Factor-Alpha (TNF-α) levels (pg/mg of tissue) from the heart [SHAM (2.74 ± 0.50, n=10) vs AMI (5.05 ± 0.83, n=8)] and renal tissue [SHAM (2.37 ± 0.69, n=7) vs AMI (5.53 ± 0.41, n=5)] were significantly different (p&lt;0.05) concerning their respective groups. Of note, molecular biochemical analyses revealed similar results. Plasma Osmolality (kgH2O): SHAM (310.8 ± 5, n=13) vs AMI (310.4 ± 2.57, n=10); Urinary Osmolality: SHAM (1653 ± 140, n=14) vs AMI (2054 ± 166.9, n=9); Plasma Creatinine (mg/dL): SHAM (0.35 ± 0.21, n=14) vs AMI (0.39 ± 0.25, n=10); Urinary Creatinine: SHAM (118.9 ± 12.35, n=14) vs AMI (126.5 ± 18.90, n=10). GFR (mL/min/100g) was also similar: SHAM (1.22 ± 0.18, n=14) vs AMI (1.22 ± 0.12, n=9). Conclusions: The study shows that the increase of TNF-α is contributing to the onset and progression of the pathophysiology of CS1, in line with the original hypothesis. On the other hand, because the three-day post-surgery timeframe addressed the primary mechanisms triggering the CS1, it seems that the functional impairment of the heart and kidneys was not manifest yet. Support or Funding Information: FAPESP Process 2020/06043-7. CNPq Processes 306994/21-6 and 423999/21-4; FAEPA; CAPES/PROEX. 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.

Sex Differences in Autoimmune Signatures After Myocardial Infarction in Mice

Myocardial infarction (MI) is caused by ischemic injury to the left ventricle (LV), leading to an acute inflammatory response, scar formation, and loss of LV function. The role of the antibody-mediated response and autoimmune (AI) development during MI is not well understood. AI disease is highly prevalent in females, which increases risk of MI and worsens MI outcomes. Thus, we hypothesized that females would exhibit increased susceptibility to MI-induced development of AI signatures, including B cell activation and autoantibody (AAB) production. Permanent MI was induced by left coronary artery ligation in adult male and female C57BL/6J mice, which were followed for 7, 28, or 56 days, using no MI (D0) as controls. LV function was tracked using echocardiography (VEVO 3100). LV infarct cytokines were measured by qPCR. LV infarct and blood leukocytes were measured by flow cytometry. LV IgG and IgM antibody deposition was measured by immunofluorescence. Plasma AABs (IgG and IgM subclasses) were measured with an autoantigen (AAN) microarray (128 AANs). In both sexes, MI led to progressive LV hypertrophy, increased end-diastolic diameter and volume, anterior/posterior wall thinning, and decreased ejection fraction. Survival was significantly higher in females for each time point (100% vs 50% at D7, 83% vs 57% at D28, 94% vs 39% at D56). MI increased spleen mass/tibia length in D7, 28, and 56 females, but decreased spleen mass in D28 and 56 males. LV inflammatory cytokines (IL-1β, IL-6, IL-18, IFN-γ, TNF, CCL2, IL-10) were increased at D7. In both sexes, IL-6 and IL-18 remained elevated at D28 and 56. Blood and LV myeloid cells were increased at D7 in both sexes, while B and T cells were decreased. At D28, myeloid cells returned to D0 levels; LV activated B cells (CD80+) and T cells (CD3+) were increased. At D56, only B cells remained elevated in the LV. IgG deposition was increased in the female LV at D7 (14.1±1.2% area fraction vs 6.3±1.5% D0) and further at D28 (40.4±3.6%), but only at D28 in males (20.4±4.0% vs 3.1±0.7% D0). Both sexes exhibited increased LV IgM at D7 and 28, however, the IgM response at D7 was higher in females (21.1±2.8% vs 8.3±1.6% in males). In plasma, MI increased AABs against several AANs (p&lt;0.05 vs D0). Compared to D0, D7 females had elevated IgG AABs 1 AAN (dsDNA, a classical AI marker) vs 0 for males, and elevated IgM AABs against 4 different AANs versus 1 for males. D28 females had elevated IgG AABs against 1 AAN vs 4 for males, and elevated IgM AABs against 5 AANs vs 0 in males. D56 females had elevated IgG AABs against 34 AANs vs 9 in males, and elevated IgM AABs against 30 AANs versus 1 for males. For both IgG and IgM AABs in D56 females, several were against AANs highly expressed in the heart, including ACE2, mitochondrion, and myosin. Furthermore, D56 female IgM AABs were increased against IL-6 (9.8±0.8 fold change), which as mentioned earlier, remained elevated in the LV at all post-MI time points. In summary, MI promotes development of AI signatures, including LV B and T cell activation, IgG and IgM antibody deposition, and increased circulating AABs, which is exacerbated in females. NHLBI R01 HL166737 (Mouton), AHA Career Development Award CDA856365 (Mouton), NIH/NHLBI R00 HL146888 (Taylor), U54 HL169191 (Taylor), NIGMS P20 GM104357 (Hall), P30 GM149404 (Hall), U54 GM115428 (Hall), NHLBI R01 HL1630376 (da Silva), NIDDK R01 DK121411 (do Carmo), AHA Postdoctoral Fellowship 835218 (Omoto). 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.

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.

Notum protects against myocardial infarction-induced heart dysfunction by alleviating cardiac fibrosis

Abstract Background and Objective Cardiac fibrosis is a pathological reparative process that follows myocardial infarctionand is associated with compromised cardiac systolic and reduced cardiac compliance. The Wnt signaling pathway is closely implicated in organ fibrosis, and Notum, a highly conserved secreted inhibitor, modulates Wnt signaling. The objective of this study was to explore the role and mechanism of Notum in cardiac fibrosis. Methods A mouse model of cardiac remodeling was established through left coronary artery ligation surgery, with the addition of Notum injection following myocardial infarction surgery. The protective effect of Notum on myocardial infarction was assessed by evaluating cardiac function, including survival rate, echocardiographic assessment, and cardiac contraction analyses. Inflammatory cell necrosis and infiltration were confirmed through H&amp;E and Masson staining. The expression of fibrosis-related genes and β-catenin pathway markers was detected using Western blot quantificational RT-PCR (qRT-PCR). Additionally, EdU, wound healing, and immunofluorescence staining analyses were performed to detect the effect of Notum’s in transforming growth factor beta-1 (TGF-β1) induced myofibroblast transformation. Results The administration of Notum treatment resulted in enhanced survival rates, improved cardiac function, and decreased necrosis and infiltration of inflammatory cells in mice subjected to left coronary artery ligation. Furthermore, Notum effectively impeded the senescence of cardiac fibroblasts and hindered their pathological transformation into cardiac fibroblasts. Additionally, it significantly reduced collagen production and attenuated the activation of the Wnt/β-catenin pathway. Our preliminary investigations successfully demonstrated the therapeutic potential of Notum in both fibroblasts in vitro and in a mouse model of myocardial infarction-induced cardiac fibrosis in vivo. Conclusion Notum inhibition of the Wnt/β-catenin signaling pathway and cardiac fibroblast senescence ultimately hampers the onset of cardiac fibrosis. Our findings suggest that Notum could represent a new therapeutic strategy for the treatment of cardiac fibrosis.

Effects of Electronic Cigarette Vaping on Cardiac and Vascular Function, and Post-myocardial Infarction Remodeling in Rats

The effect of electronic cigarette (E-cig) vaping on cardiac and vascular function during the healing phase of myocardial infarction (MI), and post-MI remodeling was investigated. Sprague Dawley rats were subjected to left coronary artery ligation to induce MI. One week later, rats were randomized to receive either 12 weeks of exposure to purified air (n = 37) or E-cig vapor (15 mg/ml of nicotine) (n = 32). At 12 weeks, cardiac and vascular function, and post-MI remodeling were assessed. Baseline blood flow in the femoral artery did not differ between groups, but peak reperfusion blood flow was blunted in the E-cig group (1.59 ± 0.15 ml/min) vs. the air group (2.11 ± 0.18 ml/min; p = 0.034). Femoral artery diameter after reperfusion was narrower in the E-cig group (0.54 ± 0.02 mm) compared to the air group (0.60 ± 0.02 mm; p = 0.023). Postmortem left ventricular (LV) volumes were similar in the E-cig (0.69 ± 0.04 ml) and air groups (0.73 ± 0.04 ml; p = NS); and myocardial infarct expansion index did not differ between groups (1.4 ± 0.1 in E-cig group versus 1.3 ± 0.1 in air group; p = NS). LV fractional shortening by echo did not differ between groups at 12 weeks (E-cig at 29 ± 2% and air at 27 ± 1%; p = NS). Exposure to E-cig during the healing phase of MI was associated with altered vascular function with reduced femoral artery blood flow and diameter at reperfusion, but not with worsened LV dilation or worsened cardiac function.

Natural shear wave measurements detect changes in operational stiffness induced by mechanical ventilation in sheep

Abstract Shear wave elastography (SWE) has the potential to non-invasively measure myocardial stiffness, based on the propagation speed of shear waves traveling through the myocardium after valve closure. However, shear wave propagation speed (SWS) is related to the operational stiffness of the heart, which is defined by the slope of the end-diastolic stress-strain relationship at the operating volume/pressure. Therefore, operational stiffness can be altered by both changes in intrinsic myocardial stiffness and myocardial loading conditions. We aimed to investigate whether SWE can detect differences in operational stiffness induced by loading changes during mechanical ventilation, and whether SWE combined with respiratory hold manoeuvres could detect an evolution in stiffness during the course of ischemic cardiomyopathy (ICM). We assessed SWS in 8 sedated and mechanically ventilated sheep: 1 healthy control, 3 within 8 weeks, and 4 after at least 16 weeks following left coronary artery ligation (early vs. late ICM). Left ventricular parasternal long-axis views were acquired with a state-of-the-art ultrasound scanner with high frame rate technology (&amp;gt; 1100 Hz). Shear waves after mitral valve closure were considered during an inspiratory hold at 30 cmH2O and 15 cmH2O and expiratory hold at 0 cmH2O (atmospheric pressure). We used linear regression to assess the trend of the SWS during ventilation manoeuvres per animal and a two-tailed Student’s T-test to assess changes between ICM stages and their respective response to ventilation manoeuvres. In all but one sheep, SWS declined with higher inspiratory pressures (see fig. 1), possibly due to a reduction in preload at higher inspiratory pressures resulting in a shift towards a reduced slope on the myocardial stress-strain relation. The sheep with a positive slope was excluded from further analyses. SWS during expiratory hold at atmospheric pressure was 3.4 m/s in the healthy control and was significantly lower in early vs. late ICM (mean±SD 4.0±0.6 vs. 9.0±1.7 m/s; p=0.007). Furthermore, the change in SWS was larger in late vs. early ICM (slope of regression line -0.16 vs. -0.05 m/s/cmH2O; p=0.03). These observations suggest loading on a steeper part of the end-diastolic stress strain relationship in late ICM. In conclusion, our results suggest that SWE is able to detect differences in operational stiffness induced by mechanical ventilation. Secondly, SWE appears to distinguish between different time points in the course of ICM based on the magnitude of the SWS during expiratory hold at atmospheric pressure, but also on the magnitude of the SWS change during loading alterations induced by mechanical ventilation. Further work should assess whether SWE combined with respiratory hold manoeuvres could contribute to differentiate intrinsic from hemodynamic stiffening, and to exploit its full potential as a non-invasive bedside method for the assessment of operational stiffness.

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.

Abstract 17810: Sustained Natural Heart Regeneration After Myocardial Infarction in One-Week-Old Rats Without Significant Cardiomyocyte Proliferation

Introduction: Newborn mammals are capable of natural heart regeneration after cardiac injury during the first week of life, but whether a decline in cardiomyocyte (CM) proliferation directly leads to the loss of regenerative potential is unknown. We hypothesized that, after myocardial infarction (MI) in neonatal rats, the extent of regeneration is directly correlated with the degree of CM proliferation. Methods: Neonatal Wistar rats, including both males and females, underwent left coronary artery ligation to induce MI on postnatal day 1 (P1, n=12), day 7 (P7, n=14), day 8 (P8, n=14), or day 9 (P9, n=15). Sham surgery was performed at each age (n=14, 13, 12, 16, respectively). CM proliferation was assessed using Ki67 staining in a subset of each age group, sacrificed 1 week after MI (n=4, 3, 5, 4) or sham surgery (n=4, 3, 3, 5). At 9 weeks post-MI, echocardiography was performed, and the hearts were explanted for Masson’s trichome staining. Results: At 9 weeks after surgery, left ventricular (LV) end-diastolic diameter (Fig 1A) and ejection fraction (EF, Fig 1B) were similar for P1 MI vs P1 sham (EF 62.5±5.2% vs 62.4±3.3%, p=0.941), as well as for P7 MI vs P7 sham (EF 61.4±3.3% vs 63.3±3.3%, p=0.210), consistent with robust natural regeneration. Progressive LV remodeling, dysfunction, and scar formation were observed after P8 MI (EF 50.1±2.6% vs 63.5±3.6%, p&lt;0.001) and P9 MI (EF 39.4±3.4% vs 63.1±3.9%, p&lt;0.001), but minimal scar was observed after P1 MI and P7 MI (Fig 1C). While the proportion of Ki67-positive CM was increased after P1 MI vs P1 Sham (4.0±2.0% vs 0.5±0.5%, p=0.013), CM proliferation was not significantly increased after P7 MI (1.0±0.4% vs 0.3±0.4%, p=0.105), or after P8 or P9 MI (Fig 1D). Conclusions: In rats, CM proliferation is not significantly stimulated after P7 MI, but the hearts develop with preserved geometry, normal function, and minimal infarct. Further studies are needed to examine non-CM-related mechanisms influencing the extent of natural heart regeneration.

Myocardial infarction elevates endoplasmic reticulum stress and protein aggregation in heart as well as brain.

Cardiovascular diseases, including myocardial infarction (MI), constitute the leading cause of morbidity and mortality worldwide. Protein-aggregate deposition is a hallmark of aging and neurodegeneration. Our previous study reported that aggregation is strikingly elevated in hearts of hypertensive and aged mice; however, no prior study has addressed MI effects on aggregation in heart or brain. Here, we present novel data on heart and brain aggregation in mice following experimental MI, induced by left coronary artery (LCA) ligation. Infarcted and peri-infarcted heart tissue, and whole cerebra, were isolated from mice at sacrifice, 7 days following LCA ligation. Sham-MI mice (identical surgery without ligation) served as controls. We purified detergent-insoluble aggregates from these tissues, and quantified key protein constituents by high-resolution mass spectrometry (LC-MS/MS). Infarct heart tissue had 2.5- to 10-fold more aggregates than non-infarct or sham-MI heart tissue (each P = 0.001). Protein constituents from MI cerebral aggregates overlapped substantially with those from human Alzheimer's disease brain. Prior injection of mice with mesenchymal stem cell (MSC) exosomes, shown to limit infarct size after LCA ligation, reduced cardiac aggregation ~ 60%, and attenuated markers of endoplasmic reticulum (ER) stress in heart and brain (GRP78, ATF6, P-PERK) by 50-75%. MI also elevated aggregate constituents enriched in Alzheimer's disease (AD) aggregates, such as proteasomal subunits, heat-shock proteins, complement C3, clusterin/ApoJ, and other apolipoproteins. These data provide novel evidence that aggregation is elevated in mouse hearts and brains after myocardial ischemia, leading to cognitive impairment resembling AD, but can be attenuated by exosomes or drug (CDN1163) interventions that oppose ER stress.

Anomalous origin of left coronary artery from the pulmonary artery: Our 30 years of surgical experience and outcomes.

Background: The aim of this study was to evaluate our 30 years of surgical experience and outcomes in management of anomalous origin of left coronary artery from the pulmonary artery with various age groups. Methods: Between March 1992 and August 2022, a total of 21 patients (10 males, 11 females; mean age: 16.3±15.9 years; range, 1 to 64 years) diagnosed with anomalous origin of left coronary artery from the pulmonary artery who underwent successful surgical repair were retrospectively analyzed. An initial diagnosis was made with two-dimensional echocardiography. Cardiac catheterization and angiography were performed in all our patients. Results: The median follow-up was five (range, 1 to 14) years. The mean left ventricular ejection fraction was 43.47±14.30% with associated moderate-to-severe mitral regurgitation in seven (33.33%) patients. Coronary button transfer was performed in 15 (71.42%) patients, Takeuchi repair in four (19.04%) patients, and ligation of anomalous left main coronary artery and ligation with great saphenous venous graft in one (4.76%) patient. There was no mortality. However, two (9.52%) patients had prolonged intensive care unit stay (>7 days). At the final follow-up, the mean left ventricular ejection fraction improved to 57.47±4.97%. Regression of moderate mitral regurgitation was observed in four (66.6%) patients. Conclusion: Preoperative left ventricular function is a major risk factor of perioperative mortality and morbidity. Mitral valve intervention is not warranted concomitantly in patients with moderate mitral regurgitation, if there are no structural lesions. Early diagnosis and meticulous surgical technique can yield excellent results and good long-term outcomes.

Abstract P3150: Extracellular Vesicles From Endothelial Progenitor Cells Limit The Development Of Ventricular Dysfunction In A Mouse Model Of Myocardial Infarction

After myocardial infarction (MI), angiogenesis in the ischemic myocardium is essential for an optimal reparative process to limit the development of ventricular dysfunction. Cell-derived extracellular vehicles (EVs) are emerging as the next-generation strategy in tissue engineering. In this study, we aimed to determine the role of EVs derived from endothelial progenitor cells (EPC) in cardiac function post-MI. EVs were purified from the supernatant of EPC by density gradient centrifugation. MI was induced in C57BL/6 mice (n=23) by left coronary artery ligation and confirmed by EKG. Mice were randomized to receive purified EVs (n=10) or saline (n=10) in two zones of the myocardium, peri-ischemic and central ischemia zones, followed by weekly I.P. injection of EVs or saline for six weeks. Three mice underwent sham surgical procedures without coronary artery ligation. Cardiac magnetic resonance at the end of the follow-up showed significant impairment of left ventricle (LV) performance in the saline group, which was better preserved in mice treated with EVs (Fig 1) . Histological analysis in the LV showed increased collagen deposition in both MI groups (Fig 2A) . However, capillary density decreased more pronouncedly in the saline than in the EV group (Fig 2B) . Quantitative mRNA array revealed a differential relative mRNA expression in the EV group compared to saline (Fig 3) . The administration of EPC-derived EVs has a modest effect on preventing the development of LV adverse remodeling after ischemia, as it limits LV dilation at the long term in a mouse model of chronic MI.Funding: ISCIII (PI19/00264, SEC/FECINV- BAS 20/012)

Abstract P2153: A Long Noncoding RNA Plentiful In Cardiosphere-derived Cell Extracellular Vesicles (CDC-EVs), BCYRN1, And Its Short Synthetic Derivatives Enhance Regulatory T Cell (Treg) Proliferation, Migration, And Activation

Background: By modulating inflammation, Treg cells influence outcomes in myocardial infarction (MI). Here, we test the hypothesis that BCYRN1 (Brain Cytoplasmic RNA 1) and BCYRN1-derived binding small sequences (BDSSs) are cardioprotective by activating Tregs. Methods: RNA sequencing identified BCYRN1 as plentiful in cardiosphere-derived cell extracellular vesicles (CDC-EVs), validated by qPCR. RNA pulldown and luciferase assays probed BCYRN1's potential function as a miRNA sponge. We assessed BCYRN1 and BDSS effects on Treg proliferation (Cell Counting Kit-8), migration (trans-well migration), and IL-10 (qPCR and ELISA). In vivo , MI was induced in C57BL/6 mouse by left coronary artery ligation for 45 minutes followed by 15 minutes reperfusion. Afterwards, mice received (via tail vein) CDC-EV-BCYRN1 (CDC-EVs overexpressing BCYRN1), BDSSs, mut-BDSSs (scrambled inactive versions of BDSS) or vehicle (PBS). MI size (by TTC staining) and infiltrating Treg (by flow cytometry) were assessed 72 hrs post-MI. Findings: BCYRN1 was found to contain putative binding sites for miR-138, miR-150 and miR-98; these miRs target ATG7, CCR6 and IL-10 mRNAs, respectively. BCYRN1 serves as a miRNA sponge, leading to Treg cell ATG7/autophagy dependent proliferation (3.0± 0.1 fold increase, N=5), CCR-6 dependent migration (1.8 ± 0.1 fold increase, N=5) and increased IL-10 production (fold increase, qPCR: 2.6 ± 0.4, N=6 and ELISA: 6.1 ± 0.8, N=5). Lipid nanoparticles containing a cocktail of 3BDSSs likewise induce Treg cell proliferation (1.9± 0.6 fold increase, N=6), migration (1.3± 0.2 fold increase, N=6), and IL-10 induction (6.8± 0.5 fold increase, N=6). In vivo (N=5/group), CDC-EV-BCYRN1 (but not vehicle) and BDSS cocktail (but not mut-BDSS) induced Treg infiltration, proliferation and IL10 production in the heart with a concomitant decrease of infarct size. Conclusions: A single LncRNA (BCYRN1) and shorter synthetic derivatives mimic the effects of CDC-EV on Treg in vitro and in vivo . Our study provides a novel approach, targeting Treg, to treat MI. This approach could be useful for other diseases where increased Treg activity is a therapeutic goal (e.g. autoimmune disorders).

Qishen granules regulate intestinal microecology to improve cardiac function in rats with heart failure.

Qishen Granule (QSG), a clinically approved traditional Chinese medicine, has been researched for treating heart failure (HF) for many years. However, the effect of QSG on intestinal microecology remains unconfirmed. Therefore, this study aimed to elucidate the possible mechanism of QSG regulating HF in rats based on intestinal microecological changes. A rat model with HF induced by myocardial infarction was prepared by left coronary artery ligation. Cardiac functions were assessed by echocardiography, pathological changes in the heart and ileum by hematoxylin-eosin (HE) and Masson staining, mitochondrial ultrastructure by transmission electron microscope, and gut microbiota by 16S rRNA sequencing. QSG administration improved cardiac function, tightened cardiomyocytes alignment, decreased fibrous tissue and collagen deposition, and reduced inflammatory cell infiltration. Electron microscopic observation of mitochondria revealed that QSG could arrange mitochondria neatly, reduce swelling, and improve the structural integrity of the crest. Firmicutes were the dominant component in the model group, and QSG could significantly increase the abundance of Bacteroidetes and Prevotellaceae_NK3B31_group. Furthermore, QSG significantly reduced plasma lipopolysaccharide (LPS), improved intestinal structure, and recovered barrier protection function in rats with HF. These results demonstrated that QSG was able to improve cardiac function by regulating intestinal microecology in rats with HF, suggesting promising therapeutic targets for HF.

Activating transcription factor 4 drives the progression of diabetic cardiac fibrosis.

Diabetic cardiomyopathy (DC) is one of serious complications of diabetic patients. This study investigated the biological function of activating transcription factor 4 (ATF4) in DC. Streptozotocin-treated mice and high glucose (HG)-exposed HL-1 cells were used as the in vivo and in vitro models of DC. Myocardial infarction (MI) was induced by left coronary artery ligation in mice. Cardiac functional parameters were detected by echocardiography. Target molecule expression was determined by real time quantitative PCR and western blotting. Cardiac fibrosis was observed by haematoxylin and eosin and Masson's staining. Cardiac apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labelling. Activities of superoxide dismutase, glutathione peroxidase, and levels of malonic dialdehyde and reactive oxygen species were used to assess oxidative stress damage. Molecular mechanisms were evaluated by chromatin immunoprecipitation, dual luciferase assay, and co-immunoprecipitation. ATF4 was up-regulated in the DC and MI mice (P<0.01). Down-regulation of ATF4 improved cardiac function as evidenced by changes in cardiac functional parameters (P<0.01), inhibited myocardial collagen I (P<0.001) and collagen III (P<0.001) expression, apoptosis (P<0.001), and oxidative stress (P<0.001) in diabetic mice. Collagen I (P<0.01) and collagen III (P<0.01) expression was increased in MI mice, which was reversed by ATF4 silencing (P<0.05). ATF4 depletion enhanced viability (P<0.01), repressed apoptosis (P<0.001), oxidative damage (P<0.001), and collagen I (P<0.001), and collagen III (P<0.001) expression of HG-stimulated HL-1 cells. ATF4 transcriptionally activated Smad ubiquitin regulatory factor 2 (Smurf2, P<0.001) to promote ubiquitination and degradation of homeodomain interacting protein kinase-2 (P<0.001) and subsequently caused inactivation of nuclear factor erythroid 2-related factor 2/heme oxygenase 1 pathway (P<0.001). The inhibitory effects of ATF4 silencing on HG-induced apoptosis (P<0.01), oxidative injury (P<0.01), collagen I (P<0.001), and collagen III (P<0.001) expression were reversed by Smurf2 overexpression. ATF4 facilitates diabetic cardiac fibrosis and oxidative stress by promoting Smurf2-mediated ubiquitination and degradation of homeodomain interacting protein kinase-2 and then inactivation of nuclear factor erythroid 2-related factor 2/heme oxygenase 1 pathway, suggesting ATF4 as a treatment target for DC.

RyR2 inhibition with dantrolene is antiarrhythmic, prevents further pathological remodeling, and improves cardiac function in chronic ischemic heart disease

Diastolic Ca2+ leak due to cardiac ryanodine receptor (RyR2) hyperactivity has been widely documented in chronic ischemic heart disease (CIHD) and may contribute to ventricular tachycardia (VT) risk and progressive left-ventricular (LV) remodeling. Here we test the hypothesis that targeting RyR2 hyperactivity can suppress VT inducibility and progressive heart failure in CIHD by the RyR2 inhibitor dantrolene. Methods and resultsCIHD was induced in C57BL/6 J mice by left coronary artery ligation. Four weeks later, mice were randomized to either acute or chronic (6 weeks via implanted osmotic pump) treatment with dantrolene or vehicle. VT inducibility was assessed by programmed stimulation in vivo and in isolated hearts. Electrical substrate remodeling was assessed by optical mapping. Ca2+ sparks and spontaneous Ca2+ releases were measured in isolated cardiomyocytes. Cardiac remodeling was quantified by histology and qRT-PCR. Cardiac function and contractility were measured using echocardiography. Compared to vehicle, acute dantrolene treatment reduced VT inducibility. Optical mapping demonstrated reentrant VT prevention by dantrolene, which normalized the shortened refractory period (VERP) and prolonged action potential duration (APD), preventing APD alternans. In single CIHD cardiomyocytes, dantrolene normalized RyR2 hyperactivity and prevented spontaneous intracellular Ca2+ release. Chronic dantrolene treatment not only reduced VT inducibility but also reduced peri-infarct fibrosis and prevented further progression of LV dysfunction in CIHD mice. ConclusionsRyR2 hyperactivity plays a mechanistic role for VT risk, post-infarct remodeling, and contractile dysfunction in CIHD mice. Our data provide proof of concept for the anti-arrhythmic and anti-remodeling efficacy of dantrolene in CIHD.

Bufalin reduces myocardial infarction-induced myocardial fibrosis and improves cardiac function by inhibiting the NLRP3/IL-1β signalling pathway.

Early inflammatory responses post myocardial infarction (MI) is associated with increased myocardial fibrosis and cardiac remodelling. The NLRP3 inflammasome, a key factor in this response, regulates the expression of interleukins (IL)-1β and IL-18. Inhibiting the inflammatory process may be beneficial for post-MI recovery. Bufalin effectively inhibits inflammation and fibrosis. The aim of this study was to evaluate the effects of bufalin and MCC950, an NLRP3 inflammasome inhibitor, as potential treatment agents for MI using an experimental mouse model. Male C57BL/6 mice were subjected to left coronary artery ligation to induce MI and subsequently treated with bufalin (0.5 mg/kg), MCC950 (10 mg/kg) or saline thrice a week for 2 weeks. After 4 weeks, cardiac function and myocardial fibrosis were evaluated. Myocardial levels of fibrotic markers and inflammatory factors were analysed using western blotting, enzyme-linked immunosorbent assay, real-time quantitative polymerase chain reaction and immunofluorescence. In mice with MI, cardiac ultrasonography showed decreased cardiac function and myocardial fibrosis. Bufalin treatment restored left ventricular ejection fraction and fractional shortening and decreased the myocardial infarct size. Moreover, both bufalin and MCC950 preserved cardiac function and relieved myocardial fibrosis, with no significant difference. Hence, the present study findings suggest that bufalin can alleviate fibrosis and improve cardiac function in a mouse model by suppressing NLRP3/IL-1β signalling post-MI.

Cardiomyocyte-specific GPR22 overexpression ameliorates cardiac injury in mice with acute myocardial infarction

The activation of G protein-coupled receptors (GPCR) signaling by external stimuli has been thought to play roles in inducing cardiac stress and stress responses. GPR22 is an orphan GPCR expressed in brains and hearts, while its expression level is associated with cardiovascular damages in diabetes. Previous studies indicated that loss of GPR22 expression increases the susceptibility to heart failure-post ventricular pressure overload, suggesting a protective role of GPR22 in mechanical cardiac stress. However, the participation and underlying signaling of GPR22 in cardiac stress response to ischemic stress remain unknown. In this study, we applied cultured cells and a transgenic mouse model with cardiomyocyte-specific GPR22 overexpression to examine the influence of ischemic stress on GPR22 expression as well as to determine the role of GPR22 in myocardial ischemic injury. To induce acute myocardial infarction (AMI), left coronary artery ligation was performed on eight-week-old male GPR22 transgenic mice, followed by histopathological and biochemical examination four weeks post-induction of AMI. Results showed that GPR22 expressions in H9C2 and RL-14 cells, two cardiomyocyte cell lines, were reduced by cobalt chloride (CoCl 2 ) treatment. Reduced expression of myocardial GPR22 was also observed in mice with acute myocardial infraction (AMI). Histopathological examinations demonstrated the protective role of GPR22 overexpression in ameliorating myocardial infarction in mice with AMI. Furthermore, the myocardial level of Bcl-2 and activation of PI3K-Akt signaling were reduced by ischemic stress and increased by GPR22 over-expression. In conclusion, myocardial ischemic stress reduced the cardiac expression of GPR22, while overexpression of GPR22 in cardiomyocytes upregulated Akt signaling and ameliorated myocardial injury induced by ischemic stress. This research was funded by the Chang Gung Medical Foundation (CMRPG 8K0321) and the National Science and Technology Council, Taiwan (NSC 111-2320-B-182A-005-MY2) This is the full abstract presented at the American Physiology Summit 2023 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.