Left Ventricular Fractional Shortening Research Articles

A novel BAG5 variant impairs the ER stress response pathway, causing dilated cardiomyopathy and arrhythmia

Pathogenic BAG5 variants recently linked to dilated cardiomyopathy (DCM) prompt further investigation into phenotypic, mutational, and pathomechanistic aspects. We explored the clinical and molecular characteristics of DCM associated with BAG5 variants, uncovering the consistently severe manifestations of the disease and its impact on the endoplasmic reticulum (ER) stress response. The analysis involved three siblings affected by DCM and arrhythmia, along with their four unaffected siblings, their unaffected father, and their mother who exhibited arrhythmia. The parents were consanguineous. Exome and Sanger sequencing identified a novel BAG5 variant, c.444_445delGA (p.Lys149AsnfsTer6), homozygous in affected siblings and heterozygous in parents and unaffected siblings. We generated heterozygous and homozygous Bag5 point mutant knock-in (KI) mice and evaluated cardiac pathophysiology under stress conditions, including tunicamycin (TN) administration. Bag5−/− mice displayed no abnormalities up to 12 months old and showed no anomalies during an exercise stress test. However, following TN injection, Bag5−/− mice exhibited significantly reduced left ventricular fractional shortening (LVFS) and ejection fraction (LVEF). Their cardiac tissues exhibited a notable increase in apoptotic cells, despite non-distinctive changes in CHOP and GRP78 levels. Interestingly, only Bag5 KI male mice demonstrated arrhythmia, which was more pronounced in Bag5−/− than in Bag5+/−males. Here, our study reveals a novel BAG5 mutation causing DCM by impairing the ER stress response, with observed sex-specific arrhythmia differences.

#1755 Cardio-protective effect of soy proteins during long-term consumption of Cynomolgus Monkeys high-saline diet

Abstract Background and Aims High salt intake is accompanied by the development of cardiovascular disorders, not always associated with an increase in blood pressure (BP). Recently, it has been found that the introduction of soy protein into the diet can have some nephroprotective and cardioprotective effects in chronic kidney disease. Considering the cardioprotective effect of soy proteins in chronic kidney disease, the question arose about the possibility of using soy proteins to neutralize the damaging effect of a high-salt diet on the cardiovascular system. This work aims to study the effect of long-term use of a diet high in NaCl and soy protein on myocardial remodeling in monkeys. Method The study was performed on male Macaca fascicularis. The animals were divided into three groups (6 animals each), comparable in weight and age (6-8 years, body weight - 5.15-9.7 kg). The control group received a standard diet (2 g NaCl/kg feed). The second was a high salt diet (8 g NaCl/kg feed), and the third was a high salt diet and SUPRO760 soy protein (200 g/kg feed). Echocardiography (EchoCG), registration of BP and heart rate were performed at baseline, after 4 and 12 months. EchoCG was performed with a sector transducer with a frequency of 3–5 MHz on the Chison SonoTouch 60 ultrasound system (China). EchoCG was performed in B_mode (two-dimensional scanning), M_mode (one-dimensional scanning), as well as in pulse and tissue Doppler modes. Statistical analysis was performed using parametric statistics: mixed ANOVA in comparing data from 3 study groups (with post hoc analysis using Tukey criterion) and single factor variance analysis for related samples in studying the dynamics of one or another index in each group during the 12-month follow-up. Differences were considered significant at p < 0.05. Results In animals of all three groups for 12 months, blood pressure (BPsis-109±10.09, BPdias – 60 ± 7.42 mm Hg) and heart rate (77 ± 12.61 min-1) did not change significantly (p>0. 05). However, in macaques on a high-salt diet, deterioration in left ventricular (LV) systolic and diastolic function was noted by the end of the study. Macaques of this group had a decrease in the LV shortening fraction (27.9±2.69%) and an increase in the thickness of the posterior wall of the LV in systole (0.69±0.039 cm), LV mass (19.60±2.83 g), compared with animals additionally receiving soy proteins (34.9±6.57%; 0.57 0.0559 cm; 14.86±2.94 g, respectively; all p < 0.05). In addition, the monkeys receiving soy isolate did not differ from the control in these parameters. By the time the study was completed, the animals in this group had significantly increased the magnitude of systolic excursion of the mitral annulus plane, and signs of improvement in LV diastolic function appeared in the form of an increase in the maximum rate of excursion of the mitral valve fibrous annulus in early diastole, as well as a decrease in the E/e' ratio. The thickness of the interventricular septum also decreased (0.42±0.04 cm; in the high-salt group - 0.51±0.08 cm), which can be interpreted as a sign of positive myocardial remodeling. Conclusion Thus, high salt intake leads to adverse structural and functional disorders of the heart in cynomolgus monkeys, not associated with an increase in blood pressure. The inclusion of soy isolate in the diet reduces the negative effects of a high-salt diet on the cardiovascular system.

V-A ECMO for neonatal coxsackievirus B fulminant myocarditis: a case report and literature review

BackgroundNeonatal (enteroviral) myocarditis (NM/NEM) is rare but unpredictable and devastating, with high mortality and morbidity. We report a case of neonatal coxsackievirus B (CVB) fulminant myocarditis successfully treated with veno-arterial extracorporeal membrane oxygenation (V-A ECMO).Case presentationA previously healthy 7-day-old boy presented with fever for 4 days. Progressive cardiac dysfunction (weak heart sounds, hepatomegaly, pulmonary edema, ascites, and oliguria), decreased left ventricular ejection fraction (LVEF) and fractional shortening (FS), transient ventricular fibrillation, dramatically elevated creatine kinase-MB (405.8 U/L), cardiac troponin I (25.85 ng/ml), and N-terminal pro-brain natriuretic peptide (NT-proBNP > 35,000 ng/L), and positive blood CVB ribonucleic acid indicated neonatal CVB fulminating myocarditis. It was refractory to mechanical ventilation, fluid resuscitation, inotropes, corticosteroids, intravenous immunoglobulin, and diuretics during the first 4 days of hospitalization (DOH 1–4). The deterioration was suppressed by V-A ECMO in the next 5 days (DOH 5–9), despite the occurrence of bilateral grade III intraventricular hemorrhage on DOH 7. Within the first 4 days after ECMO decannulation (DOH 10–13), he continued to improve with withdrawal of mechanical ventilation, LVEF > 60%, and FS > 30%. In the subsequent 4 days (DOH 14–17), his LVEF and FS decreased to 52% and 25%, and further dropped to 37%–38% and 17% over the next 2 days (DOH 18–19), respectively. There was no other deterioration except for cardiomegaly and paroxysmal tachypnea. Through strengthening fluid restriction and diuresis, and improving cardiopulmonary function, he restabilized. Finally, notwithstanding NT-proBNP elevation (>35,000 ng/L), cardiomegaly, and low LVEF (40%–44%) and FS (18%–21%) levels, he was discharged on DOH 26 with oral medications discontinued within 3 weeks postdischarge. In nearly three years of follow-up, he was uneventful, with interventricular septum hyperechogenic foci and mild mitral/tricuspid regurgitation.ConclusionsDynamic cardiac function monitoring via real-time echocardiography is useful for the diagnosis and treatment of NM/NEM. As a lifesaving therapy, ECMO may improve the survival rate of patients with NM/NEM. However, the “honeymoon period” after ECMO may cause the illusion of recovery. Regardless of whether the survivors of NM/NEM have undergone ECMO, close long-term follow-up is paramount to the prompt identification and intervention of abnormalities.

Balloon Valvuloplasty in Congenital Critical Aortic Valve Stenosis in Neonates and Infants: A Rescue Procedure for the Left Ventricle.

Congenital critical aortic valve stenosis (CAVS) is a life-threatening disease requiring urgent treatment. First-line therapy is still controversial. The aim of our study was (1) to analyze retrospectively the patients of our institution who underwent balloon aortic valvuloplasty (BAV) due to CAVS and (2) describe the techniques for improved feasibility of intervention using microcatheters and retrieval loops. Twelve patients underwent 23 BAVs: 1 BAV was performed in 3 patients, 2 BAVs were performed in 7 patients, and 3 BAVs were performed in 2 patients. The peak trans-valvular pressure gradient (Δp) and left ventricular shortening fraction (LVSF) improved significantly in the first two interventions. In the first BAV, Δp decreased from 73.7 ± 34.5 mmHg to 39.8 ± 11.9 mmHg (p = 0.003), and the LVSF improved from 22.3 ± 13.5% to 31.6 ± 10.2% (p = 0.001). In the second BAV, Δp decreased from 73.2 ± 33.3 mmHg to 35.0 ± 20.2 mmHg (p < 0.001), and the LVSF increased from 26.7 ± 9.6% to 33.3 ± 7.4% (p = 0.004). Cardiac surgery during the neonatal period was avoided for all children. The median time to valve surgery was 5.75 years. Few complications occurred, namely mild-to-moderate aortic regurgitation, one remediable air embolism, and one intimal injury to the ascending aorta. We conclude that BAV is a successful emergency treatment for CAVS, resulting in left ventricular relief, clinical stabilization, and a time gain until cardiac surgery.

Shexiang Tongxin Dropping Pill Promotes Angiogenesis through VEGF/eNOS Signaling Pathway on Diabetic Coronary Microcirculation Dysfunction.

To study the effect of Shexiang Tongxin Dropping Pill (STDP) on angiogenesis in diabetic cardiomyopathy mice with coronary microcirculation dysfunction (CMD). According to a random number table, 6 of 36 SPF male C57BL/6 mice were randomly selected as the control group, and the remaining 30 mice were injected with streptozotocin intraperitoneally to replicate the type 1 diabetes model. Mice successfully copied the diabetes model were randomly divided into the model group, STDP low-dose group [15 mg/(kg·d)], medium-dose group [30 mg/(kg·d)], high-dose group [60 mg/(kg·d)], and nicorandil group [15 mg/(kg·d)], 6 in each group. The drug was given by continuous gavage for 12 weeks. The cardiac function of mice in each group was detected at the end of the experiment, and coronary flow reserve (CFR) was detected by chest Doppler technique. Pathological changes of myocardium were observed by hematoxylin-eosin staining, collagen fiber deposition was detected by masson staining, the number of myocardial capillaries was detected by platelet endothelial cell adhesion molecule-1 staining, and the degree of myocardial hypertrophy was detected by wheat germ agglutinin staining. The expression of the vascular endothlial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS) signaling pathway-related proteins in myocardial tissue was detected by Western blot. Compared with the model group, medium- and high-dose STDP significantly increased the left ventricular ejection fraction and left ventricular fraction shortening (P<0.01), obviously repaired the disordered cardiac muscle structure, reduced myocardial fibrosis, reduced myocardial cell area, increased capillary density, and increased CFR level (all P<0.01). Western blot showed that high-dose STDP could significantly increase the expression of VEGF and promote the phosphorylation of vascular endothelial growth factor receptor 2, phosphoinositide 3-kinase, protein kinase B, and eNOS (P<0.05 or P<0.01). STDP has a definite therapeutic effect on diabetic CMD, and its mechanism may be related to promoting angiogenesis through the VEGF/eNOS signaling pathway.

Exosomal let-7a-5p derived from human umbilical cord mesenchymal stem cells alleviates coxsackievirus B3-induced cardiomyocyte ferroptosis via the SMAD2/ZFP36 signal axis.

Viral myocarditis (VMC) is one of the most common acquired heart diseases in children and teenagers. However, its pathogenesis is still unclear, and effective treatments are lacking. This study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes (CMCs) induced by coxsackievirus B3 (CVB3). CVB3 was utilized for inducing the VMC mouse model and cellular model. Cardiac echocardiography, left ventricular ejection fraction (LVEF), and left ventricular fractional shortening (LVFS) were implemented to assess the cardiac function. In CVB3-induced VMC mice, cardiac insufficiency was observed, as well as the altered levels of ferroptosis-related indicators (glutathione peroxidase 4 (GPX4), glutathione (GSH), and malondialdehyde (MDA)). However, exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exo) could restore the changes caused by CVB3 stimulation. Let-7a-5p was enriched in hucMSCs-exo, and the inhibitory effect of hucMSCs-exolet-7a-5p mimic on CVB3-induced ferroptosis was higher than that of hucMSCs-exomimic NC (NC: negative control). Mothers against decapentaplegic homolog 2 (SMAD2) increased in the VMC group, while the expression of zinc-finger protein 36 (ZFP36) decreased. Let-7a-5p was confirmed to interact with SMAD2 messenger RNA (mRNA), and the SMAD2 protein interacted directly with the ZFP36 protein. Silencing SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related indicators. Meanwhile, the levels of GPX4, solute carrier family 7, member 11 (SLC7A11), and GSH were lower in the SMAD2 overexpression plasmid (oe-SMAD2)+let-7a-5p mimic group than in the oe-NC+let-7a-5p mimic group, while those of MDA, reactive oxygen species (ROS), and Fe2+ increased. In conclusion, these data showed that ferroptosis could be regulated by mediating SMAD2 expression. Exo-let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36, which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.

Interval training suppresses nod-like receptor protein 3 inflammasome activation to improve cardiac function in myocardial infarction rats by hindering the activation of the transforming growth factor-β1 pathway

ObjectiveMyocardial infarction (MI) -induced cardiac dysfunction can be attenuated by aerobic exercises. This study explored the mechanism of interval training (IT) regulating cardiac function in MI rats, providing some theoretical basis for clarifying MI pathogenesis and new ideas for clinically treating MI.MethodsRats were subjected to MI modeling, IT intervention, and treatments of the Transforming growth factor-β1 (TGF-β1) pathway or the nod-like receptor protein 3 (NLRP3) activators. Cardiac function and hemodynamic indicator alterations were observed. Myocardial pathological damage and fibrosis, reactive oxygen species (ROS) level, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities, MDA content, inflammasome-associated protein levels, and inflammatory factor levels were assessed. The binding between TGF-β1 and receptor was detected.ResultsMI rats exhibited decreased left ventricle ejection fraction (LVEF), left ventricle fractional shortening (LVFS), left ventricular systolic pressure (LVSP), positive and negative derivates max/min (dP/dt max/min) and increased left ventricular end-systolic pressure (LVEDP), a large number of scar areas in myocardium, disordered cell arrangement and extensive fibrotic lesions, increased TGF-β1 and receptor binding, elevated ROS level and MDA content and weakened SOD, CAT and GSH-Px activities, and up-regulated NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC) and cleaved-caspase-1 levels, while IT intervention caused ameliorated cardiac function. IT inactivated the TGF-β1 pathway to decrease oxidative stress in myocardial tissues of MI rats and inhibit NLRP3 inflammasome activation. Activating NLRP3 partially reversed IT-mediated improvement on cardiac function in MI rats.ConclusionIT diminished oxidative stress in myocardial tissues and suppressed NLRP3 inflammasome activation via inactivating the TGF-β1 pathway, thus improving the cardiac function of MI rats.

Cardiac function is regulated by the sodium-dependent inhibition of the sodium-calcium exchanger NCX1

The Na+-Ca2+ exchanger (NCX1) is the dominant Ca2+ extrusion mechanism in cardiac myocytes. NCX1 activity is inhibited by intracellular Na+ via a process known as Na+-dependent inactivation. A central question is whether this inactivation plays a physiological role in heart function. Using CRISPR/Cas9, we inserted the K229Q mutation in the gene (Slc8a1) encoding for NCX1. This mutation removes the Na+-dependent inactivation while preserving transport properties and other allosteric regulations. NCX1 mRNA levels, protein expression, and protein localization are unchanged in K229Q male mice. However, they exhibit reduced left ventricular ejection fraction and fractional shortening, while displaying a prolonged QT interval. K229Q ventricular myocytes show enhanced NCX1 activity, resulting in action potential prolongation, higher incidence of aberrant action potentials, a faster decline of Ca2+ transients, and depressed cell shortening. The results demonstrate that NCX1 Na+-dependent inactivation plays an essential role in heart function by affecting both cardiac excitability and contractility.

Potential clinical value of fibrinogen-like protein 1 as a serum biomarker for the identification of diabetic cardiomyopathy

Diabetic individuals with diabetic cardiomyopathy (DbCM) present with abnormal myocardial structure and function. DbCM cannot be accurately diagnosed due to the lack of suitable diagnostic biomarkers. In this study, 171 eligible participants were divided into a healthy control (HC), type 2 diabetes mellitus (T2DM) patients without DbCM (T2DM), or DbCM group. Serum fibrinogen-like protein 1 (FGL-1) and other biochemical parameters were determined for all participants. Serum FGL-1 levels were significantly higher in patients with DbCM compared with those in the T2DM group and HCs. Serum FGL-1 levels were negatively correlated with left ventricular fractional shortening and left ventricular ejection fraction (LVEF) and positively correlated with left ventricular mass index in patients with DbCM after adjusting for age, sex and body mass index. Interaction of serum FGL-1 and triglyceride levels on LVEF was noted in patients with DbCM. A composite marker including serum FGL-1 and triglycerides could differentiate patients with DbCM from those with T2DM and HCs with an area under the curve of 0.773 and 0.789, respectively. Composite marker levels were negatively correlated with N-terminal B-type natriuretic peptide levels in patients with DbCM. Circulating FGL-1 may therefore be a valuable index reflecting cardiac functions in DbCM and to diagnose DbCM.

A novel mechanism of major ginsenosides from Panax ginseng against multiple organ aging in middle-aged mice: Phosphatidylcholine-myo-inositol metabolism based on metabolomic analysis

Aging is a complex, degenerative process associated with various metabolic abnormalities. Ginsenosides (GS) is the main active components of Panax ginseng, which has anti-aging effects and improves metabolism. However, the anti-aging effect and the mechanism of GS in middle-aged mice has not been elucidated. In this study, GS after 3-month treatment significantly improved the grip strength, fatigue resistance, cognitive indices, and cardiac function of 15-month-old mice. Meanwhile, GS treatment reduced the fat content and obviously inhibited histone H2AX phosphorylation at Ser 139 (γ-H2AX), a marker of DNA damage in major organs, especially in the heart and liver. Further, the correlation analysis of serum metabolomics combined with aging phenotype suggested that myo-inositol (MI) upregulated by GS was positively correlated with left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), the main indicators of cardiac function. More importantly, liver tissue metabolomic analysis showed that GS increased MI content by promoting the synthesis pathway from phosphatidylcholine (PC) to MI for the inhibition of liver aging. Finally, we proved that MI reduced the percentage of senescence-associated β-galactosidase staining, γ-H2AX immunofluorescence staining, p21 expression, and the production of reactive oxygen species in H2O2-induced cardiomyocytes. These results suggest that GS can enhance multiple organ functions, especially cardiac function for promoting the healthspan of aging mice, which is mediated by the conversion of PC to MI in the liver and the increase of MI level in the serum. Our study might provide new insights into the potential mechanisms of ginsenosides for prolonging the healthspan of natural aging mice.

Baicalin alleviates angiotensin II-induced cardiomyocyte apoptosis and autophagy and modulates the AMPK/mTOR pathway.

As a main extraction compound from Scutellaria baicalensis Georgi, Baicalin exhibits various biological activities. However, the underlying mechanism of Baicalin on hypertension-induced heart injury remains unclear. Invivo, mice were infused with angiotensin II (Ang II; 500 ng/kg/min) or saline using osmotic pumps, followed by intragastrically administrated with Baicalin (5 mg/kg/day) for 4 weeks. Invitro, H9C2 cells were stimulated with Ang II (1 μM) and treated with Baicalin (12.5, 25 and 50 μM). Baicalin treatment significantly attenuated the decrease in left ventricular ejection fraction and left ventricular fractional shortening, increase in left ventricular mass, left ventricular systolic volume and left ventricular diastolic volume of Ang II infused mice. Moreover, Baicalin treatment reversed 314 differentially expressed transcripts in the cardiac tissues of Ang II infused mice, and enriched multiple enriched signalling pathways (including apoptosis, autophagy, AMPK/mTOR signalling pathway). Consistently, Baicalin treatment significantly alleviated Ang II-induced cell apoptosis invivo and invitro. Baicalin treatment reversed the up-regulation of Bax, cleaved-caspase 3, cleaved-caspase 9, and the down-regulation of Bcl-2. Meanwhile, Baicalin treatment alleviated Ang II-induced increase of autophagosomes, restored autophagic flux, and down-regulated LC3II, Beclin 1, as well as up-regulated SQSTM1/p62 expression. Furthermore, autophagy inhibitor 3-methyladenine treatment alleviated the increase of autophagosomes and the up-regulation of Beclin 1, LC3II, Bax, cleaved-caspase 3, cleaved-caspase 9, down-regulation of SQSTM1/p62 and Bcl-2 expression after Ang II treated, which similar to co-treatment with Baicalin. Baicalin treatment reduced the ratio of p-AMPK/AMPK, while increased the ratio of p-mTOR/mTOR. Baicalin alleviated Ang II-induced cardiomyocyte apoptosis and autophagy, which might be related to the inhibition of the AMPK/mTOR pathway.

CD8 Cell PHD2 Deficiency Amplifies Pressure Overload-Induced Cardiac Inflammation through Metabolic Reprogramming of CD8 Cells

Prolyl hydroxylase domain (PHD) proteins function as oxygen sensors and regulate various cellular metabolism. PHD2 is well-known for its role in oxygen sensing and has been implicated in cardiac hypertrophy and fibrosis through HIF-2α. However, the specific impact and the mechanism of CD8 cell PHD2 deficiency on cardiac inflammation and heart failure (HF) development remains unclear. Here, we explored the role of CD8 cell-specific PHD2 deficiency (CD8-PHD2 KO) in HF development by using transverse aortic constriction (TAC) mouse model. Our findings reveal that CD8 PHD2 knockout exacerbated TAC-induced left ventricular (LV) hypertrophy, as evidenced by increased LV weight relative to bodyweight or tibial length. CD8-PHD2 KO also leads to a significant increase in lung and right ventricular weight relative to bodyweight or tibial length following TAC. Furthermore, CD8-PHD2 KO worsens TAC-induced reductions in LV ejection fraction, LV fractional shortening, and LV dilatation. Additionally, CD8-PHD2 KO exacerbates TAC-induced LV cardiomyocyte hypertrophy, fibrosis, and immune cell infiltration. Moreover, our study demonstrated that CD8-PHD2 KO amplified the infiltration and activation of antigen-presenting cells, CD4 T cells, and CD8 T cells in the heart and lungs after TAC. At the molecular level, we characterized the PHD2-deficient CD8 cells showed typical features of anaerobic glycolysis, which were paralleled by augmented hypoxia-inducible factor 1α (HIF-1α) protein levels. Collectively, these results highlight the critical role of PHD2 in CD8 cells in regulating cardiac inflammation and HF development in response to systolic overload. National Institutes of Health Project Number 5R01HL161085-02. 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.

γδ T Cells Mediate Pressure Overload-Induced Cardiac Inflammation, Hypertrophy, Heart Failure Development, and Heart Failure Progression

Gamma delta T cells (γδ T cells) are T cells that have a γδ T-cell receptor (TCR) on their surface. γδ T cells display broad functional plasticity following recognition of infected or injured cells by production of cytokines and chemokines, and cytolysis of the infected or injured cells. However, the role of γδ T cells in heart failure (HF) development and HF progression is unknown. To investigate the role of γδ T cells in HF development and progression, we studied the effect of transverse aortic constriction (TAC) on cardiac inflammation, hypertrophy, and dysfunction in both wild type and TCRδ gene deficient (TCRδ−/−) mice, as TCRδ−/− mice have no γδ T cells. Interestingly, TCRδ−/− significantly attenuated TAC-induced left ventricular (LV) hypertrophy as evidenced by less increase of LV weight and its ratio to bodyweight or tibial length. TCRδ−/− also significantly attenuated TAC-induced increase of lung weight, right ventricular weight, and their ratio to bodyweight or tibial length. TCRδ−/− also significantly reduced TAC-induced decease of LV ejection fraction and LV fractional shortening, and LV dilatation. Furthermore, TCRδ−/− significantly attenuated TAC-induced LV cardiomyocyte hypertrophy, fibrosis, and immune cell infiltration. Moreover, we found that TCRδ−/− significantly reduced TAC-induced infiltration and activation of pulmonary antigen presenting cells, CD4 T cells and CD8 T cells. Together, these data indicate that γδ T cells exert an important role in promoting systolic overload-induced cardiac inflammation, HF development, and HF progression. This work was supported by NIH research grants R01HL161085, R01HL139797, P20GM104357, and P30GM149404. 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.

No sex differences in the cardiac responses during high altitude sojourn to 4300 m

Ascent to high altitude reduces oxygen availability and provokes compensatory cardiovascular responses. Females may exhibit attenuated hypoxic ventilatory responses compared to males, which could subsequently exaggerate the cardiovascular response to high altitude among females. The purpose of this study was to examine sex differences in cardiac responses during high altitude sojourn in young, healthy males and females. We hypothesized that females would exhibit a greater reduction in arterial oxygen saturation, and greater cardiac dysfunction compared to males. 17 healthy adults (8 males, 24±4 yrs, BMI 25.7±3.1 kg/m2; 9 females, 23±4 yrs, BMI 24.5±3.0 kg/m2) underwent cardiac assessment via echocardiography at 1400 m and after an 8-day ascent to 4300 m. Left ventricular (LV) systolic function was assessed via ejection fraction and fractional shortening. Diastolic function was assessed as the ratio between early and late mitral filling velocities (E:A ratio). The subendocardial viability ratio (SEVR) was derived from carotid tonometry, and carotid pressure waves were integrated with echocardiography derived measures of left ventricular ejection to estimate a left ventricular pressure-volume loop and calculate stroke work. Ascent from 1400 m to 4300 m resulted in reduced end-tidal CO2 (-Δ8±3 [males], -Δ8±2 mmHg [females], p&lt;0.001), oxygen saturation (-Δ11±3 [males], -Δ11±5 % [females], p&lt;0.001), and LV fractional shortening (-Δ7.9±7.5% [males] -Δ1.0±6.4 % [females], p=0.028) in both groups. Despite greater stroke work among males (p=0.002), high altitude-induced changes were not statistically different compared to females (+Δ35±184 [males], +Δ3±113 mL/mmHg [females]). Changes in LV ejection fraction (-Δ1.9±14.4 [males], -Δ1.5±18.7 % [females]) mitral E:A (-Δ0.33±0.53 [males], -Δ0.09±0.64 au [females]), and SEVR (-Δ0.06±0.33 [males], +Δ0.15±0.20 au [females]) from 1400 to 4300 m were not statistically different between sexes. Ascent from 1400 to 4300 m decreased end-tidal CO2, arterial oxygen saturation, and select metrics of LV systolic function (e.g., fractional shortening), but LV diastolic function, stroke work, and SEVR was preserved in both males and females. We observed no apparent sex differences in the effects of 8-day sojourn to 4300 m on arterial oxygen saturation, or cardiac systolic and diastolic function. Additional research is necessary to confirm these results in the context of longer-term altitude exposure and acclimatization, and in older populations (middle-aged and older adults). 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.

Cardiorenal Effects of Chronic High Phosphate Diet in Female Rats

Cardiorenal Syndrome Type 4 (CRS4) refers to the development of cardiovascular dysfunction as a result of chronic kidney disease. The accumulation of circulating phosphate in the later stages of chronic kidney disease (CKD) has been positively associated with cardiac hypertrophy and dysfunction. In our previous work, we found that male Sprague Dawley rats that underwent 5/6 nephrectomy (5/6Nx) to induce CKD phenotypes also developed cardiac pathology when serum phosphorus levels became elevated. Small RNA sequencing of left ventricle tissue revealed upregulated microRNA-21-5p and -3p expression in 5/6Nx rats, when compared to sham-operated controls, and suppression of miR-21-5p attenuated left ventricle pathology in male 5/6Nx rats. We hypothesize that hyperphosphatemia, independent of CKD, can impair cardiac function and that miR-21 may mediate these effects. It has been recently reported that females exhibit higher urinary phosphate excretion in response to high dietary phosphate intake than males. In this study, hyperphosphatemia was induced by placing 9-week old female wild-type (WT) Sprague Dawley and global miR-21 knockout (miR-21−/−; lacking both miR-21-5p and -3p rats) (n=4-9/group) on either high phosphate (2% Pi) or control diet (0.6% Pi) for 8 weeks. Echocardiography and renal ultrasound were performed under anesthesia to assess cardiac function and renal cross-sectional area, respectively, prior to tissue collection at endpoint. Rats of either genotype fed 2% Pi diet exhibited increased left kidney weight, left kidney/body weight, and left kidney cross-sectional area (2-way ANOVA, main effect of diet; p&lt;0.05). In animals fed 2% Pi, miR-21−/− rats had significantly higher left ventricle fractional shortening than WT rats (57.06 ± 3.32 vs. 43.96 ± 1.34; 2-way ANOVA with Tukey multiple comparisons; p&lt;0.05). This study allowed the cardiovascular effects of chronically elevated phosphate to be isolated from other uremic toxins elevated in CKD. We find that loss of miR-21 augments cardiac function, supporting a role for miR-21 in mediating phosphate-related pathology. Ongoing studies are focused on identifying specific molecular mechanisms driving these changes. This study was supported by T32HL007852 and R01HL128332. 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.

Effect of acute high-intensity interval exercise on a mouse model of doxorubicin-induced cardiotoxicity: a pilot study

BackgroundIt is unknown whether high-intensity interval exercise (HIIE) may potentiate or attenuate the cardiotoxic effect of chemotherapy agents such as doxorubicin (DOX) when performed shortly after treatment. The study aimed to investigate the effect of acute HIIE on cardiac function and structure performed either 1, 2 or 3 days after DOX injection in an animal model.MethodsFemale C57bl/6 mice (n = 28), 70 days old, received a bolus 20 mg/kg intravenous tail vein DOX injection. Three exercise groups performed 1 HIIE session (16 sets of 1 min at 85–90% of peak running speed) at 1 (n = 7), 2 (n = 7), and 3 days (n = 8) following the DOX injection. A sedentary (SED) group of mice (n = 6) did not exercise. Animals underwent echocardiography under light anesthesia (isoflurane 0.5-1%) before and 7 days after the DOX injection. Animals were sacrificed on day 9 and hearts were collected for morphometric and histological analysis.ResultsAnimals exercising on day 3 had the smallest pre-post reduction in left ventricular fractional shortening (LVFS) (MΔ= -1.7 ± 3.3; p = 0.406) and the SED group had the largest reduction (MΔ=-6.8 ± 7.5; p = 0.009). After reclassification of animals according to their exercise compliance (performing > 8/16 of high-intensity bouts), LVFS in compliant mice was unchanged over time (LVFS MΔ= -1.3 ± 5.6; p = 0.396) while non-compliant animals had a LVFS reduction similar to sedentary animals. There were no significant differences in myocardial histology between groups.ConclusionsIn this pilot murine study, one single HIIE session did not exacerbate acute doxorubicin-induced cardiotoxicity. The timing of the HIIE session following DOX injection and the level of compliance to exercise could influence the negative impact of DOX on cardiac function.

Fetal left and right ventricular strain parameters using speckle tracking in congenital heart diseases.

Assessment of fetal ventricular function is mostly subjective, and currently, for the objective assessment left ventricular shortening fraction is obtained. However, this by itself is not very reliable. Hence, more tools that can provide an objective assessment are needed to increase the confidence of functional assessment. Speckle tracking imaging can provide one such tool. In this study we sought to establish the normative value of global longitudinal and circumferential strain for our fetal patients and for two major forms of congenital heart diseases, namely atrioventricular canal defects (AVC) and uncorrected dextro-transposition of the great arteries (dTGA) to act as a benchmark. The study was completed via a single center retrospective analysis on 72 fetal echocardiograms (26 normal, 15 dTGA, and 31 AVC). Tomtec Arena™ echocardiography analysis software was used for analysis. In normal fetuses, mean left ventricular (LV) global longitudinal strain (GLS) was - 22.6% (95% CI -24, -21.1) and mean right ventricular (RV) GLS was - 22.1% (95% CI -23.6, -20.6). In AVC patients LV GLS was-26.6% (95% CI -28,-25.3) and mean RV GLS was - 26.5% (95% CI -27.9,-25.2). In dTGA patients LV GLS was - 22.9% (95% CI of -24.8, -21) and RV GLS was - 21.3% (95% CI was - 23.4, -20.8). There was good intra-rater reliability though poor to fair inter-rater reliability. Notwithstanding its current limitations, strain imaging can provide useful information that can increase confidence of cardiac functional assessment in fetal patients. However, to be reliable across the board, further automation and standardization is required.

HAPLN1 knockdown inhibits heart failure development via activating the PKA signaling pathway

BackgroundHeart failure (HF) is a heterogeneous syndrome that affects millions worldwide, resulting in substantial health and economic burdens. However, the molecular mechanism of HF pathogenesis remains unclear.MethodsHF-related key genes were screened by a bioinformatics approach.The impacts of HAPLN1 knockdown on Angiotensin II (Ang II)-induced AC16 cells were assessed through a series of cell function experiments. Enzyme-linked immunosorbent assay (ELISA) was used to measure levels of oxidative stress and apoptosis-related factors. The HF rat model was induced by subcutaneous injection isoprenaline and histopathologic changes in the cardiac tissue were assessed by hematoxylin and eosin (HE) staining and echocardiographic index. Downstream pathways regulated by HAPLN1 was predicted through bioinformatics and then confirmed in vivo and in vitro by western blot.ResultsSix hub genes were screened, of which HAPLN1, FMOD, NPPB, NPPA, and COMP were overexpressed, whereas NPPC was downregulated in HF. Further research found that silencing HAPLN1 promoted cell viability and reduced apoptosis in Ang II-induced AC16 cells. HAPLN1 knockdown promoted left ventricular ejection fraction (LVEF) and left ventricular fraction shortening (LVFS), while decreasing left ventricular end-systolic volume (LVESV) in the HF rat model. HAPLN1 knockdown promoted the levels of GSH and suppressed the levels of MDA, LDH, TNF-α, and IL-6. Mechanistically, silencing HAPLN1 activated the PKA pathway, which were confirmed both in vivo and in vitro.ConclusionHAPLN1 knockdown inhibited the progression of HF by activating the PKA pathway, which may provide novel perspectives on the management of HF.

Neuronal nitric oxide synthase required for erythropoietin modulation of heart function in mice.

Introduction: Erythropoietin (EPO) acts primarily in regulating red blood cell production mediated by high EPO receptor (EPOR) expression in erythroid progenitor cells. EPO activity in non-erythroid tissue is evident in mice with EPOR restricted to erythroid tissues (ΔEPORE) that become obese, glucose-intolerant, and insulin-resistant. In animal models, nitric oxide synthase (NOS) contributes to EPO activities including erythropoiesis, neuroprotection, and cardioprotection against ischemia-reperfusion injury. However, we found that extended EPO treatment to increase hematocrit compromised heart function, while the loss of neuronal NOS (nNOS) was protective against the deleterious activity of EPO to promote heart failure. Methods: Wild-type (WT) mice, ΔEPORE mice, and nNOS-knockout mice (nNOS-/-) were placed on a high-fat diet to match the ΔEPORE obese phenotype and were treated with EPO for 3weeks. Hematocrit and metabolic response to EPO treatment were monitored. Cardiac function was assessed by echocardiography and ultrasonography. Results: ΔEPORE mice showed a decrease in the left ventricular outflow tract (LVOT) peak velocity, ejection fraction, and fractional shortening, showing that endogenous non-erythroid EPO response is protective for heart function. EPO treatment increased hematocrit in all mice and decreased fat mass in male WT, demonstrating that EPO regulation of fat mass requires non-erythroid EPOR. EPO treatment also compromised heart function in WT mice, and decreased the pulmonary artery peak velocity (PA peak velocity), LVOT peak velocity, ejection fraction, and fractional shortening, but it had minimal effect in further reducing the heart function in ΔEPORE mice, indicating that the adverse effect of EPO on heart function is not related to EPO-stimulated erythropoiesis. ΔEPORE mice had increased expression of heart failure-associated genes, hypertrophic cardiomyopathy-related genes, and sarcomeric genes that were also elevated with EPO treatment in WT mice. Male and female nNOS-/- mice were protected against diet-induced obesity. EPO treatment in nNOS-/- mice increased the hematocrit that tended to be lower than WT mice and decreased the PA peak velocity but did not affect the LVOT peak velocity, ejection fraction, and fractional shortening, suggesting that nNOS is required for the adverse effect of EPO treatment on heart function in WT mice. EPO treatment did not change expression of heart failure-associated gene expression in nNOS-/- mice. Discussion: Endogenous EPO has a protective effect on heart function. With EPO administration, in contrast to the protective effect to the cardiac injury of acute EPO treatment, extended EPO treatment to increase hematocrit in WT mice adversely affected the heart function with a corresponding increase in expression of heart failure-associated genes. This EPO activity was independent of EPO-stimulated erythropoiesis and required EPOR in non-erythroid tissue and nNOS activity, while nNOS-/- mice were protected from the EPO-associated adverse effect on heart function. These data provide evidence that nNOS contributes to the negative impact on the heart function of high-dose EPO treatment for anemia.

Echocardiographic assessment of cardiovascular involvements in children with cystic fibrosis

BackgroundOver the past four decades, numerous case reports and clinical studies have highlighted the presence of heart disease in individuals with cystic fibrosis. Given the limited information in this field and the imperative to identify early changes during childhood, our study aims to explore cardiac dysfunction in patients with cystic fibrosis using echocardiography. MethodsIn this case-control study, we examined echocardiographic findings from thirty-three patients with cystic fibrosis and sixty healthy children. Demographic information for both groups was recorded, and the disease severity in patients was assessed using the Schawachman criterion. M-mode, Doppler flow velocity, and Tissue Doppler Imaging echocardiography were performed for all participants, with subsequent data analysis using SPSS 24. ResultsOur study encompassed thirty-three CF patients and sixty healthy children. The estimated pulmonary artery blood pressure (systolic and mean) in patients with cystic fibrosis was significantly higher than in the control group (P < 0.05). Additionally, the mean trans-tricuspid peak early to late diastolic flow velocity (E/A) was significantly lower in the case group than the control group (P < 0.05), along with a significantly lower mean tricuspid valve deceleration time (DT) (P < 0.05). Similarly, the mean TAPSE in the case group was notably lower than in the control group (P < 0.05). No significant difference in Mean left ventricular Ejection Fraction (EF) and Fractional Shortening (FS) existed between the two groups (P > 0.05). Furthermore, Trans-mitral peak early to late diastolic flow velocity (E/A) in the case group was significantly lower than in the control group (P < 0.05), and the mean mitral valve DT in the case group was also significantly lower (P < 0.05). ConclusionOur study findings indicate the presence of some degree of right ventricular dysfunction in children with cystic fibrosis. This finding may have implications for the development or modification of clinical guidelines for managing cystic fibrosis in children. Further investigations are recommended to elucidate the underlying mechanisms and contributing factors, providing valuable insights for clinical management.