Search Results (412)

Reptiles with diving capabilities have evolved physiological adaptations as well as conformational changes to temporarily sustain life underwater. Despite the importance of both respiratory and cardiovascular systems during diving, most studies have focused on respiratory adaptations. Thus, characterisation of previously undescribed cardiovascular anatomical variations in diving vertebrates is of broad interest. Thirteen clinically healthy, free-ranging adult female Murray River turtles (Chelidae: Emydura macquarii) were collected for research purposes, euthanised and autopsied. Prominent, valve-like structures, comprised exclusively of smooth muscle myocytes, were identified in medium- and large-calibre muscular arteries of all individuals. Additionally, multiple intramural vascular channels, mimicking post-thrombotic recanalization, were observed within medium-calibre muscular arteries. Further, we confirmed the presence of alpha-smooth-muscle actin-positive cells lining the cardiac atria in E. macquarii. Quantitative morphometric analyses demonstrated that the valve-like structures frequently occupied a substantial proportion of the vascular lumen, in some cases exceeding 90% luminal narrowing. Their consistent presence across multiple individuals and organ systems supports the interpretation that these are physiological vascular structures rather than artefacts. This study examines the potential physiological and evolutionary roles of these vascular structures, providing a basis for further research into cardiovascular adaptations in vertebrates subjected to postural changes and diving-related haemodynamic challenges. Full article

Type-1 ryanodine receptor (RyR1) is essential for skeletal muscle contraction. This Ca²⁺ release channel is expressed in cardiac myocytes; however, its function remains elusive. Cardiac-specific RyR1 overexpression (OE) mice were generated under the cardiac-specific Myh6 promoter. Cardiac hypertrophy (CH), cardiac functions, and mechanistic changes in RyR1 OE and control (wildtype, WT) mice were assessed using hematoxylin and eosin staining, echocardiography, electrocardiogram, quantitative RT-PCR, Western blotting, [³H]-ryanodine binding assay, confocal microscope, ROS dye Amplex Red and 2′,7′-dichlorofluorescein diacetate. RyR1 OE mice had increased whole heart, left ventricular weight, and left ventricular wall thickness, but decreased cardiac output and stroke volume, thereby presenting CH and heart failure (HF). CH markers like ANF, BNF, and aSKA mRNAs were increased in RyR1 OE heart. RyR1, but not RyR2 or RyR3, expression was increased in the RyR1 OE mouse heart. Similar results were found in mice with TAC-induced CH. RyR1, but not RyR2 mRNA, was increased in cardiac muscle from dogs and humans with CH and/or HF. Maximum [³H]-ryanodine binding was increased, whereas the binding dissociation constant decreased in left ventricular cardiomyocytes from RyR1 OE mice. RyR2-dependent Ca²⁺ sparks were increased, which was blocked by riluzole, a small molecule known to inhibit RyR2. Consistently, ROS was remarkably increased in RyR1 OE cardiac cells. We first generated cardiac-specific RyR1 OE mice; these mice had CH, HF, and increased RyR1 expression with no RyR2 or RyR3 alteration. Similar changes were observed in mice, dogs, and humans with CH and HF. Increased mitochondrial ROS-dependent RyR2 Ca²⁺ release was essential for RyR1-induced CH and HF. Full article

T-wave inversion (TWI) on an electrocardiogram (ECG) is a key indicator of myocardial ischemia, yet existing inverse ECG methods lack quantitative physiological parameter resolution. This study aims to propose a novel multiscale computational framework to inversely identify the ionic mechanisms underlying TWI. A cell–tissue–torso cardiac electrophysiological model was integrated with a differential evolution (DE) algorithm. The forward model combined the Grandi atrial model and BPS2020 ventricular model, simulating action potential propagation via cellular automata and body surface ECGs via field point potentials. The inverse solution optimized 29 physiological parameters by minimizing the root-mean-square error between the simulated and clinical ECGs. The method was applied to 30 normal and 30 TWI cases to analyze the repolarization abnormalities. The study revealed that extracellular Ca²⁺ > 2.88 mmol/L and K⁺ < 3.4 mmol/L in ventricular myocytes (Endo, M, Epi) induce TWI. Quantitative analysis identified specific 95% confidence intervals for ionic imbalances in three scenarios: Case 1 ($V_{Epi}>V_{Endo}>V_M$) with [Ca²⁺] 2.60–3.30 mmol/L and [K⁺] 1.9–4.7 mmol/L; Case 2 ($V_M>V_{Epi}>V_{Endo}$) with [Ca²⁺] 2.36–3.68 mmol/L and [K⁺] 3.13–4.07 mmol/L; and Case 3 ($V_{Epi}>V_M>V_{Endo}$) with [Ca²⁺] 2.67–3.91 mmol/L and [K⁺] 3.11–3.45 mmol/L. This approach enables cellular-scale mechanistic insights into TWI by quantifying ionic concentration changes. The framework supports the advancement of personalized cardiac diagnostics and drug development. Full article

Glucagon-like peptide (GLP)-1 receptor (GLP1R) agonists exert a multitude of beneficial cardiovascular effects beyond control of blood glucose levels and obesity reduction. GLP-1R is a G protein-coupled receptor (GPCR), coupling to adenylyl cyclase (AC)-stimulatory Gs proteins to raise cyclic 3′-5′-adenosine monophosphate (cAMP) levels in cells. cAMP exerts various effects mainly via protein kinase A (PKA) and Exchange protein directly activated by cAMP (Epac). Cardiac GLP-1R has been reported to induce atrial natriuretic peptide (ANP) secretion via Epac2, while ANP is known to inhibit aldosterone secretion from adrenocortical zona glomerulosa (AZG) cells. Herein, we tested the effects of the GLP-1R agonist liraglutide on ANP secretion in H9c2 cardiomyocytes and on angiotensin II (AngII)-induced aldosterone secretion. We also examined whether phosphodiesterase (PDE)-4 inhibition with roflumilast could potentiate liraglutide’s effects. We found that liraglutide stimulated ANP secretion from H9c2 cardiomyocytes, an effect potentiated by roflumilast but blocked by AC inhibition. Epac inhibition with ESI-09 also significantly reduced liraglutide-dependent ANP secretion in H9c2 cardiomyocytes. Moreover, application of medium from liraglutide-treated H9c2 cardiomyocytes, but not from control cardiomyocytes, led to suppression of AngII-dependent aldosterone secretion from H295R cells. This effect was blocked by cyclic guanosine monophosphate (cGMP)-dependent protein kinase inhibition (an effector of ANP) in H295R cells, while direct application of liraglutide to these cells failed to suppress AngII-induced aldosterone secretion. Again, aldosterone suppression was more potent when medium from liraglutide plus roflumilast-treated cardiomyocytes was applied to H295R cells. Taken together, these results suggest that roflumilast enhances the adrenocortical aldosterone suppression induced by GLP-1R agonists via cardiac GLP-1R/cAMP/Epac-dependent ANP secretion. Given the cardio-toxic effects of elevated aldosterone levels in the context of various heart diseases, such as post-myocardial infarction heart failure, combination of a GLP-1R agonist drug with a PDE4 inhibitor drug may be more advantageous than either agent alone in treatment of certain cardiovascular diseases. Full article

The Ca_v1.3 L-type calcium (Ca²⁺) channel plays a critical role in cardiac excitation-contraction coupling, regulating heart rate, contractility, and gene expression. The C-terminus of Ca_v1.3 has recently been shown to translocate to the nucleus and act as a transcriptional factor to modulate the function of Ca²⁺-activated K⁺ channels in atrial cardiomyocytes. However, the role of the Ca_v1.3-C-terminus in the regulation of transcription of its own Ca_v1.3 gene remains unknown. We evaluated the impact of the nuclear translocation of the Ca_v1.3-C-terminus on the transcription of the Ca_v1.3 gene and Ca_v1.3 promoter activity in vitro using cultured neonate rat ventricular myocytes (NRVMs), and mouse atrial cardiomyocytes (HL-1). Lentiviral infection of NRVMs demonstrated that the cleaved Ca_v1.3-C-terminus translocates to the nucleus where it acts as a trans-regulator. The C-terminus of Ca_v1.3 increased transcription of Ca_v1.3 in vitro in NRVMs and in vivo in mice ventricles. Additionally, MEF2 transcription factor binding sites within the Ca_v1.3 promoter may contribute to the regulatory effect of the Ca_v1.3-C-terminus. These data are the first to demonstrate unique upregulation of Ca_v1.3 transcription by its own mobile Ca_v1.3-C-terminus both in vitro and in vivo. These findings suggest that the Ca_v1.3-C-terminus has intrinsic properties as a trans-regulator of gene expression and may contribute to the modulation of cardiac function. Full article

Cardiac fibrosis is a central determinant of heart failure progression and arises from pathological remodeling characterized by fibroblast activation, myofibroblast differentiation, and excessive extracellular matrix deposition. In contrast, physiological remodeling permits adaptive cardiac growth without net fibrosis. Pregnancy represents an underexplored physiological model of reversible cardiac remodeling. In response to hemodynamic load, the maternal heart undergoes hypertrophic growth that resolves postpartum, constituting a natural paradigm of fibrosis-resistant cardiac adaptation. Pregnancy and lactation are accompanied by profound endocrine and immune reprogramming of maternal tissues. We propose that this hormonal milieu orchestrates coordinated crosstalk among endothelial cells, fibroblasts, and immune cell populations to suppress profibrotic pathways and preserve extracellular matrix homeostasis. Candidate regulators include estrogen, progesterone, prolactin family peptides, relaxin, oxytocin, and components of the renin–angiotensin–aldosterone system. During the postpartum and lactational period, prolactin and oxytocin may further promote reverse remodeling. These hormones likely act by modulating local cytokine and growth factor networks that otherwise drive fibroblast activation. By focusing on non-myocyte cardiac cells and extracellular matrix dynamics, this review positions pregnancy as a translational model to uncover endogenous anti-fibrotic mechanisms and identify novel therapeutic strategies for cardiac fibrosis. Full article

In patients, extraintestinal manifestations of inflammatory bowel disease (IBD) are attenuated ventricular contractile function and arrhythmia. To determine the mechanism of IBD-induced changes in ventricular function, we used a mouse model of dextran sodium sulfate (3.5% weight/volume; 7 days)-induced colitis. Changes in cardiac function were quantified in isolated ventricular myocytes (VM) by cell shortening, imaging of [Ca²⁺]_i, reactive oxygen species (ROS), and t-tubular density. During colitis, VMs exhibited attenuated cell-shortening and altered Ca²⁺-handling properties. A prolonged Ca²⁺ transient (CaT) rise time correlated with an increased coefficient of variation in the subcellular Ca²⁺ release and an attenuated t-tubular density. T-tubular loss was accompanied by increased ROS production, calpain-2 (CAPN2) expression, junctophilin-2 (JPH-2) cleavage, and autophagy. Inhibition of Angiotensin-converting enzyme during colitis (Perindopril: 3 mg/kg/day) prevented the increase in CAPN2, ROS production, autophagy, and t-tubular remodeling. It failed, however, to restore full length JPH-2. We conclude that, during IBD, the angiotensin II (AngII)-induced loss of t-tubular integrity and altered cellular Ca²⁺ handling can be prevented by suppression of the AngII-dependent increase in CAPN2 and autophagy and thus suppression of AngII signaling might benefit IBD patients with cardiac manifestations of the disease. Full article

Heart failure (HF) remains a leading cause of morbidity and mortality worldwide and is driven by complex, interconnected pathophysiological processes, including maladaptive cardiac remodeling, fibrosis, hypertrophy, metabolic dysregulation, and cardiomyocyte loss. MicroRNAs (miRNAs), small non-coding RNAs that act as key post-transcriptional regulators of gene expression, have emerged as important coordinators of these processes across cardiomyocytes and non-myocyte cardiac cell populations. In addition to altered expression patterns, accumulating evidence indicates that miRNA activity is dynamically influenced by regulated biogenesis, maturation, and context-dependent mechanisms of action. Through reversible translational repression and longer-term mRNA destabilization, miRNAs support adaptive responses to acute cardiac stress, whereas their persistent dysregulation contributes to remodeling pathways that promote HF progression. This comprehensive narrative review provides an integrative overview of current knowledge on the role of miRNA networks in shaping the molecular heterogeneity of heart failure across disease stages, phenotypes, and cardiac cell types. Drawing on a broad body of experimental and clinical literature, we discuss advances in understanding miRNA biogenesis, post-transcriptional control, and cell-specific effects, while highlighting conceptual developments rather than applying systematic selection criteria. We further examine the translational and clinical implications of miRNA biology, critically considering the progress of miRNA-based therapeutics alongside the biological and practical challenges that continue to limit their widespread clinical implementation. In parallel, we explore the emerging potential of circulating miRNAs as minimally invasive biomarkers that reflect upstream regulatory stress at the level of RNA processing and post-transcriptional regulation. Finally, we address the growing application of artificial intelligence and machine learning approaches to high-dimensional miRNA datasets, which enable integrative analyses across clinical, imaging, and multi-omics domains and support biomarker discovery, patient stratification, and prediction of therapeutic response. Collectively, miRNA biology, supported by systems-level and AI-driven analytical frameworks, offers a unifying perspective for understanding, classifying, and monitoring cardiac remodeling in heart failure. Full article

Ischemic heart disease is the main cause of death worldwide. Classic cardiac biomarkers, such as troponin, which are released due to myocyte necrosis, are widely used for diagnosis, but they provide limited information about the initial underlying cellular processes involved in myocardial infarction. Autophagy is now considered fundamental in the pathophysiology of cardiac ischemia and related reperfusion injury. This systematic review aims to identify and highlight candidate autophagy-related biomarkers in cardiac ischemia and infarction with potential benefits for early diagnosis, prognosis, and therapy. A comprehensive literature search was conducted up to 1 June 2025. We included studies that examined biomarkers involved in the autophagy process in cardiac ischemia/infarction, which involved humans and animal models. A total of 14 eligible articles were reviewed. Thirteen autophagy-related biomarkers were identified, including LC3-II/I, Beclin-1, ATG5, ATG7, p62, WIPI1, FGF21, CHRF, Rubicon, IL-1β, IL-18, and adiponectin. These biomarkers have a dynamic pattern, and they exhibited time-dependent changes during the different stages of myocardial infarction. Autophagy biomarkers present a promising understanding of the molecular mechanism of early myocardial ischemia and infarction. Integration of autophagy biomarkers with the classic markers should improve risk stratification, therapeutic decision-making, and prognosis in patients with ischemic heart disease. Full article

Background: Immune checkpoint inhibitors (ICIs), such as anti-programmed death (PD)-1 and anti-cytotoxic T-lymphocyte-associated protein (CTLA)-4 agents, have revolutionized oncology but are associated with immune-related adverse events (irAEs). Among these, ICI-associated myocarditis (ICI-M) is a rare but life-threatening complication, with mortality rates ranging from 27% to 50%. Objective: This narrative review summarizes the pathogenesis, epidemiology, clinical presentation, diagnostic methods, and management strategies for ICI-induced myocarditis, specifically highlighting emerging biomarkers and immunosuppressive therapeutic approaches. Results and Discussion: ICI-M typically presents within the first 65 days of treatment and is significantly more frequent with combination therapies. Pathologically, it is characterized by myocyte necrosis and massive infiltration of cluster of differentiation (CD)4+ and CD8+ T-cells, often overlapping with myositis (irM/M). Diagnosis relies on a multimodal approach. Management requires immediate ICI cessation and initiation of high-dose corticosteroids as first-line therapy. For steroid-refractory cases, second-line options include mycophenolate mofetil (MMF), intravenous immunoglobulin (IVIG), and emerging therapies like abatacept and ruxolitinib. Rechallenge with ICIs after high-grade ICI-M must be approached with extreme caution by the multidisciplinary team (MDT). Emerging biomarkers and omics techniques hold promise for earlier diagnosis and risk stratification. Conclusions: ICI-M is a rare yet highly lethal cardiac complication demanding high clinical vigilance and timely diagnosis. Management hinges on an aggressive multidisciplinary approach, aiming to minimize toxicity while balancing oncological efficacy. Full article

Background: Neonatal myocytes rely predominantly on glycolytic metabolism for survival during hypoxic conditions. During asphyxia, metabolic pathway dysregulation impairs cardiac myocyte contractility. Co-administration of dextrose and insulin may help restore metabolic homeostasis and improve cardiac function. Methods: Following blinded randomization and instrumentation, near-term lambs (138–140 days gestational age) were asphyxiated by umbilical cord occlusion until complete cardiac arrest, followed by 7 min of continued arrest to model severe asphyxia. Return of spontaneous circulation (ROSC) was defined as heart rate ≥ 100 beats per minute (bpm) and diastolic blood pressure ≥ 20 mmHg. Results: The incidence of ROSC was 3/6 in the control group compared to 5/5 in the experimental group receiving dextrose–insulin therapy, although this difference did not reach statistical significance. Conclusions: In this proof-of-concept study using a near-term ovine model of prolonged asphyxial cardiac arrest, dextrose and insulin co-administered with epinephrine were associated with improved ROSC rates although could be an association. Larger studies are needed to confirm these findings and evaluate clinical translation Full article

Background: Hydroxychloroquine (HCQ), widely used in autoimmune and inflammatory diseases, has been associated with cardiotoxicity driven by oxidative, mitochondrial, and metabolic disturbances. However, no comparative evidence exists regarding whether thiamine, thiamine pyrophosphate (TPP), or their combination (TTPC) can mitigate HCQ-induced myocardial injury. Objective: This study examined the biochemical and histopathological effects of thiamine, TPP, and their combination in a rat model of HCQ-induced cardiomyopathy. Methods: Thirty male Wistar rats were assigned to five groups: healthy control, HCQ, thiamine + HCQ, TPP + HCQ, and TTPC + HCQ. Thiamine (20 mg/kg, intraperitoneal), TPP (20 mg/kg, intraperitoneal), or TTPC (20 mg/kg each, intraperitoneal) was administered once daily, followed by HCQ (120 mg/kg, oral, twice daily). After seven days, cardiac tissue was analyzed for MDA, tGSH, SOD, and CAT, while serum TnI, lactate, and LDH were measured from tail-vein blood samples. Cardiac samples underwent histopathological examination. Results: HCQ exposure markedly increased MDA, TnI, LDH, and lactate levels while reducing tGSH, SOD, and CAT, indicating severe oxidative and metabolic insult. Thiamine co-treatment failed to ameliorate these disturbances. Conversely, TPP restored redox balance, attenuated biomarker elevations, and improved cardiac biochemical profiles. TTPC produced comparable improvements but did not exceed those of TPP alone. Histopathologically, HCQ caused pronounced myocyte degeneration and mononuclear infiltration, whereas TPP and TTPC groups showed only mild inflammatory changes with preserved myocardial architecture. Conclusions: HCQ induces a marked redox imbalance accompanied by well-defined histopathological myocardial degeneration. TPP afforded robust cardio-protection, whereas thiamine offered no meaningful benefit. Collectively, these findings position TPP as a biologically plausible, clinically relevant candidate for mitigating HCQ-induced cardiomyopathy. Full article

Background: Ischemic heart disease is the primary contributor to global mortality. The QRS-T angle at the anterior aspect of the heart serves as a significant biomarker of the heterogeneity in myocardial repolarization and the electrophysiological instability of the cardiac myocytes. A wide frontal QRS-T angle is associated with proximal vascular disease, coexistence of three-vessel disease, and increased mortality. Hereby, we aimed to examine the relationship between collateral circulation and frontal QRS-T angle in patients with chronic total occlusion (CTO). Methods: A cohort comprising 120 patients (17 females, 14.1%) who received a diagnosis of chronic total occlusion (CTO) subsequent to the administration of coronary angiography conducted for the evaluation of stable angina pectoris was incorporated into the investigation. The electrocardiographs of the patients were evaluated in detail, and the frontal QRS-T angle was calculated. The patients were categorized into two groups: subjects exhibiting an increased frontal QRS-T angle (>110° for men, >90° for women) and those presenting with a normative frontal QRS-T angle. Coronary angiographies of the patients were analyzed, and coronary collateral circulation was classified according to Rentrop classification. Results: Serum albumin level (OR = 0.711, 95% CI 0.564–0.896; p = 0.004) and poor collateral flow (OR = 17.7, 95% CI 12.2–85.3; p < 0.001) were significant predictors of raised frontal QRS-T angle. Conclusions: The frontal QRS-T angle is a novel parameter that is more reliable, consistent, and less sensitive to miscalculation and misidentification than other conventional electrocardiographic myocardial repolarization parameters. Revealing the bad collateral relationship with the frontal QRS-T angle may enable physicians to take more stringent precautions and change the risk factors related to the increased QRS-T angle in advance. Full article

Mesenchymal stem cells (MSCs) are pivotal in regenerative medicine due to their high differentiation potential and therapeutic versatility. MSCs are multipotent cells capable of differentiating into adipocytes, chondroblasts, osteoblasts, and, under specific conditions, neural, myocyte, and epidermal lineages. This cell type contributes to tissue repair, immunomodulation, and regenerative therapies for cardiac, orthopedic, and hematological disorders. Accurate identification and characterization of these stem cells are essential for both research and clinical applications. MSCs are typically defined by plastic adherence, expression of surface markers CD105, CD73, and CD90, low or absent expression of hematopoietic markers (CD45, CD34), and in vitro differentiation potential. Understanding the expression patterns and functional relevance of these surface markers is critical for improving isolation strategies, enhancing therapeutic efficacy, and minimizing adverse effects. This review provides a comprehensive overview of the principal surface markers of MSCs, highlighting their significance in stem cell biology and clinical translation. Full article

Myocardial infarction (MI) is a pathological condition associated with various cardiovascular diseases and leads to heart failure. Nuclear factor-kappa B (NF-κB) is upregulated in the infarcted heart. G protein-coupled receptor kinase 5 (GRK5) also plays a complex role in both tissue repair and maladaptive hypertrophy in cardiovascular diseases; however, its effect on NF-κB-mediated inflammation has not yet been elucidated. Thus, this study aims to investigate the effects of Amlexanox (AMX), a potential GRK5 inhibitor, in an animal model of MI by assessing its impact on GRK5-mediated NF-κB/inflammatory processes. Thirty-two male mice were randomly allocated into four groups: control, MI, (MI treated with vehicle (MI + V), and MI + AMX (AMX: 2.5 mg/100 g/day). MI was induced using ISO on days 21 and 22. The cardioprotective impacts of Amlexanox were verified by evaluating cardiac injury, inflammatory biomarker concentrations, and histopathological alterations in cardiomyocytes. MI induction was confirmed by increases in heart weight/body weight ratio (HW/BW) (p < 0.001), troponin (p < 0.001), creatine kinase (p < 0.001), and LDH (p < 0.001). Treatment with AMX resulted in a significant reduction in cardiac injury biomarkers (p < 0.001) and IL-6 (p < 0.05). The protein level of NF-κB(p65) and NF-κB(p105) was significantly increased in cardiac myocytes of the MI group. Treatment with AMX led to a significant decrease in NF-κB(p65) and (p105) expression (p < 0.01 and p < 0.001, respectively), and GRK5 and MEF2α protein levels were also upregulated. In conclusion, AMX shows potential cardioprotective effects by modulating the GRK5/MEF2-mediated NF-κB inflammatory signaling pathway. Full article