Macrophage OTUD1-CARD9 axis drives isoproterenol-induced inflammatory heart remodelling.

BACKGROUND: Chronic inflammation contributes to the progression of isoproterenol (ISO)-induced heart failure (HF). Caspase-associated recruitment domain (CARD) families are crucial proteins for initiation of inflammation in innate immunity. Nonetheless, the relevance of CARDs in ISO-driven cardiac remodelling is little explored. METHODS: This study utilized Card9-/- mice and reconstituted C57BL/6 mice with either Card9-/- or Otud1-/- marrow-derived cells. Mechanistic studies were conducted in primary macrophages, cardiomyocytes, fibroblasts and HEK-293T cells. RESULTS: Here, we demonstrated that CARD9 was substantially upregulated in murine hearts infused with ISO. Either whole-body CARD9 knockout or myeloid-specific CARD9 deletion inhibited ISO-driven murine cardiac inflammation, remodelling and dysfunction. CARD9 deficiency in macrophages prevented ISO-induced inflammation and alleviated remodelling changes in cardiomyocytes and fibroblasts. Mechanistically, we found that ISO enhances the activity of CARD9 by upregulating ovarian tumour deubiquitinase 1 (OTUD1) in macrophages. We further demonstrated that OTUD1 directly binds to the CARD9 and then removes the K33-linked ubiquitin from CARD9 to promote the assembly of the CARD9-BCL10-MALT1 (CBM) complex, without affecting CARD9 stability. The ISO-activated CBM complex results in NF-κB activation and macrophage-based inflammatory gene overproduction, which then enhances cardiomyocyte hypertrophy and fibroblast fibrosis, respectively. Myeloid-specific OTUD1 deletion also attenuated ISO-induced murine cardiac inflammation and remodelling. CONCLUSIONS: These results suggested that the OTUD1-CARD9 axis is a new pro-inflammatory signal in ISO-challenged macrophages and targeting this axis has a protective effect against ISO-induced HF. KEY POINTS: Macrophage CARD9 was elevated in heart tissues of mice under chronic ISO administration. Either whole-body CARD9 knockout or myeloid-specific CARD9 deficiency protected mice from ISO-induced inflammatory heart remodeling. ISO promoted the assembly of CBM complex and then activated NF-κB signaling in macrophages through OTUD1-mediated deubiquitinating modification. OTUD1 deletion in myeloid cells protected hearts from ISO-induced injuries in mice.

Green Synthesis and Chemical Characterization of Silver Nanoparticles by Tribulus terrestris for the Treatment of Myocardial Infarction.

Silver nanoparticles (AgNPs) are commonly utilized in the medical sector, particularly in cardiovascular applications. Nevertheless, there is a studies scarcity examining the impact of AgNPs on myocardial infarction protection. A green formulation of AgNPs was documented in the research. Different spectroscopic methods were utilized to examine the AgNPs, and their potential for treating myocardial infarction was explored. The NPs exhibited a spherical morphology upon formation. Isoproterenol (85 mg/kg) was administered to induce myocardial infarction in mice. The mice were categorized into four distinct groups (n = 15): (1) untreated; (2) normal; (3,4) AgNPs + isoproterenol at various doses (5 and 50 µg/kg). The activation of PPAR-Υ/NF-κB and subsequent cytokine release induced by lipopolysaccharide were quantified using real-time PCR and western blot techniques. Subsequent to the administration of AgNPs at different doses, the evaluation of cardiac function was conducted through biochemical, histochemical, and electrocardiogram (ECG) analysis. AgNPs significantly inhibit the levels of myocardial injury markers, reduce the incidence of mortality, and improve the condition of ventricular wall infarction. In addition, the administration of AgNPs effectively prevents the characteristic ST segment depression when compared to animals with myocardial infarction. The positive effects of AgNPs could potentially be attributed to the restoration of normal gene expression in PPAR-Υ/NF-κB/ΙκB-α/ΙΚΚα/ß and PPAR-Υ phosphorylation pathways. Additionally, the application of AgNPs led to a reduction in the levels of pro-inflammatory cytokines in the hearts of mice suffering from myocardial infarction. The expression suppression of inflammation cytokines and cell death was significantly reduced by AgNPs. Recent findings suggest that AgNPs possess cardioprotective properties on isoproterenol-induced myocardial infarction, possibly by the inhibition of NF-κB signaling and activation of PPAR-γ. To summarize, the present study introduces a contemporary therapeutic approach for treating myocardial infarction in clinical settings.

Astaxanthin ameliorated isoproterenol induced myocardial infarction via improving the mitochondrial function and antioxidant activity in rats.

The present study evaluated the cardioprotective effect of astaxanthin (ASX) against isoproterenol (ISO) induced myocardial infarction in rats via the pathway of mitochondrial biogenesis as the possible molecular target of astaxanthin. The control group was injected with normal physiological saline subcutaneously for 2 days. The second group was injected with ISO at a dose of 85 mg/kg bwt subcutaneously for 2 days. The third, fourth and fifth groups were supplemented with ASX at doses of 10, 20, 30 mg/kg bwt, respectively daily by oral gavage for 21 days then injected with ISO dose of 85 mg/kg bwt subcutaneously for 2 successive days. Isoproterenol administration in rats elevated the activities of Creatine kinase-MB (CK-MB), aspartate transaminase (AST), lactate dehydrogenase (LDH), and other serum cardiac biomarkers Troponin-I activities, oxidative stress biomarkers, malondialdehyde(MDA), Nuclear factor-kappa B (NF-KB), while it decreased Peroxisome proliferator-activated receptor-gamma coactivator (PGC-1α), Nuclear factor erythroid-2-related factor 2 (Nfe212), mitochondrial transcriptional factor A (mt TFA), mitochondrial DNA copy number and glutathione system parameters. However, Astaxanthin decreased the activities of serum AST, LDH, CK-MB, and Troponin I that elevated by ISO. In addition, it increased glutathione peroxidase and reductase activities, total glutathione and reduced GSH content, and GSH/GSSG ratio, mtDNA copy number, PGC-1α expression and Tfam expression that improved mitochondrial biogenesis while it decreased GSSG and MDA contents and NF-KB level in the cardiac tissues. This study indicated that astaxanthin relieved isoproterenol induced myocardial infarction via scavenging free radicals and reducing oxidative damage and apoptosis in cardiac tissue.

In vivo proximity proteomics uncovers palmdelphin (PALMD) as a Z-disc-associated mitigator of isoproterenol-induced cardiac injury.

Z-discs are core ultrastructural organizers of cardiomyocytes that modulate many facets of cardiac pathogenesis. Yet a comprehensive proteomic atlas of Z-disc-associated components remain incomplete. Here, we established an adeno-associated virus (AAV)-delivered, cardiomyocyte-specific, proximity-labeling approach to characterize the Z-disc proteome in vivo. We found palmdelphin (PALMD) as a novel Z-disc-associated protein in both adult murine cardiomyocytes and human pluripotent stem cell-derived cardiomyocytes. Germline and cardiomyocyte-specific Palmd knockout mice were grossly normal at baseline but exhibited compromised cardiac hypertrophy and aggravated cardiac injury upon long-term isoproterenol treatment. By contrast, cardiomyocyte-specific PALMD overexpression was sufficient to mitigate isoproterenol-induced cardiac injury. PALMD ablation perturbed the transverse tubule (T-tubule)-sarcoplasmic reticulum (SR) ultrastructures, which formed the Z-disc-associated junctional membrane complex (JMC) essential for calcium handling and cardiac function. These phenotypes were associated with the reduction of nexilin (NEXN), a crucial Z-disc-associated protein that is essential for both Z-disc and JMC structures and functions. PALMD interacted with NEXN and enhanced its protein stability while the Nexn mRNA level was not affected. AAV-based NEXN addback rescued the exacerbated cardiac injury in isoproterenol-treated PALMD-depleted mice. Together, this study discovered PALMD as a potential target for myocardial protection and highlighted in vivo proximity proteomics as a powerful approach to nominate novel players regulating cardiac pathogenesis.

Interoceptive Signals Bias Decision Making in Rhesus Macaques.

Several influential theories have proposed that interoceptive signals, sent from the body to the brain, contribute to neural processes that coordinate complex behaviors. Using pharmacological agents that do not cross the blood-brain barrier, we altered interoceptive states and evaluated their effect on decision-making in rhesus monkeys. We used glycopyrrolate, a non-specific muscarinic (parasympathetic) antagonist, and isoproterenol, a beta-1/2 (sympathetic) agonist, to create a sympathetic-dominated physiological state indexed by increased heart rate. Rhesus monkeys were trained on two variants of an approach-avoidance conflict task, where they chose between enduring mildly aversive stimuli in exchange for a steady flow of rewards, or cancelling the aversive stimuli, forgoing the rewards. The delay to interrupt the aversive stimuli and the reward were used as a measure of the cost-benefit estimation that drove the monkeys' decisions. Both drugs altered approach-avoidance decisions, substantially reducing the delay to interrupt the aversive stimuli. To determine whether this autonomic state lowered tolerance to aversive stimuli or reduced the subjective value of the reward, we tested the effects of glycopyrrolate on a food preference task. Food preference was unaltered, suggesting that the sympathetic dominated state selectively reduces tolerance for aversive stimuli without altering reward-seeking behaviors. As these drugs have no direct effect on brain physiology, interoceptive afferents are the most likely mechanism by which decision making was biased toward avoidance.

Incremental Benefit of Stepwise Nonpulmonary Vein Trigger Provocation During Catheter Ablation of Atrial Fibrillation.

BACKGROUND: The importance of nonpulmonary vein (PV) triggers for the initiation/recurrence of atrial fibrillation (AF) is well established. OBJECTIVES: This study sought to assess the incremental benefit of provocative maneuvers for identifying non-PV triggers. METHODS: We included consecutive patients undergoing first-time AF ablation between 2020 and 2022. The provocation protocol included step 1, identification of spontaneous non-PV triggers after cardioversion of AF and/or during sinus rhythm; step 2, isoproterenol infusion (3, 6, 12, and 20-30 µg/min); and step 3, atrial burst pacing to induce AF followed by cardioversion during residual or low-dose isoproterenol infusion or induce focal atrial tachycardia. Non-PV triggers were defined as non-PV ectopic beats triggering AF or sustained focal atrial tachycardia. RESULTS: Of 1,372 patients included, 883 (64.4%) underwent the complete stepwise provocation protocol with isoproterenol infusion and burst pacing, 334 (24.3%) isoproterenol infusion only, 77 (5.6%) burst pacing only, and 78 (5.7%) no provocative maneuvers (only step 1). Overall, 161 non-PV triggers were found in 135 (9.8%) patients. Of these, 51 (31.7%) non-PV triggers occurred spontaneously, and the remaining 110 (68.3%) required provocative maneuvers for induction. Among those receiving the complete stepwise provocation protocol, there was a 2.2-fold increase in the number of patients with non-PV triggers after isoproterenol infusion, and the addition of burst pacing after isoproterenol infusion led to a total increase of 3.6-fold with the complete stepwise provocation protocol. CONCLUSIONS: The majority of non-PV triggers require provocative maneuvers for induction. A stepwise provocation protocol consisting of isoproterenol infusion followed by burst pacing identifies a 3.6-fold higher number of patients with non-PV triggers.

Mst1/Hippo signaling pathway drives isoproterenol-induced inflammatory heart remodeling.

Isoproterenol (ISO) administration is a well-established model for inducing myocardial injury, replicating key features of human myocardial infarction (MI). The ensuing inflammatory response plays a pivotal role in the progression of adverse cardiac remodeling, characterized by myocardial dysfunction, fibrosis, and hypertrophy. The Mst1/Hippo signaling pathway, a critical regulator of cellular processes, has emerged as a potential therapeutic target in cardiovascular diseases. This study investigates the role of Mst1 in ISO-induced myocardial injury and explores its underlying mechanisms. Our findings demonstrate that Mst1 ablation in cardiomyocytes attenuates ISO-induced cardiac dysfunction, preserving cardiomyocyte viability and function. Mechanistically, Mst1 deletion inhibits cardiomyocyte apoptosis, oxidative stress, and calcium overload, key contributors to myocardial injury. Furthermore, Mst1 ablation mitigates endoplasmic reticulum (ER) stress and mitochondrial fission, both of which are implicated in ISO-mediated cardiac damage. Additionally, Mst1 plays a crucial role in modulating the inflammatory response following ISO treatment, as its deletion suppresses pro-inflammatory cytokine expression and neutrophil infiltration. To further investigate the molecular mechanisms underlying ISO-induced myocardial injury, we conducted a bioinformatics analysis using the GSE207581 dataset. GO and KEGG pathway enrichment analyses revealed significant enrichment of genes associated with DNA damage response, DNA repair, protein ubiquitination, chromatin organization, autophagy, cell cycle, mTOR signaling, FoxO signaling, ubiquitin-mediated proteolysis, and nucleocytoplasmic transport. These findings underscore the significance of Mst1 in ISO-induced myocardial injury and highlight its potential as a therapeutic target for mitigating adverse cardiac remodeling. Further investigation into the intricate mechanisms of Mst1 signaling may pave the way for novel therapeutic interventions for myocardial infarction and heart failure.

Protective effects of 3, 4-dihydroxybenzoic acid on myocardial infarction induced by isoproterenol in rats.

Despite considerable advances in interventions and treatment, there is a high mortality rate in patients with myocardial infarction (MI). This is the first study to investigate the protective effects of 3, 4-dihydroxybenzoic acid against isoproterenol induced MI in rats. MI was induced by isoproterenol (100-mg/kg body weight) in rats. Then, rats were treated with 3, 4-dihydroxybenzoic acid (16-mg/kg body weight) for 2 weeks. Serum creatine kinase-MB, cardiac troponin-T, cardiac troponin-I, and heart thiobarbituric acid reactive substances were significantly (p < 0.05) increased and heart superoxide dismutase and catalase activities were significantly (p < 0.05) reduced in isoproterenol-induced myocardial infarcted rats. Isoproterenol induction significantly (p < 0.05) elevated the plasma homocysteine and serum high sensitivity-C-reactive protein levels. Furthermore, an enzyme-linked immunosorbent assay, reverse transcription polymerase chain study, and immunohistochemical (IHC) staining revealed significantly (p < 0.05) elevated levels and expression of serum/myocardial nuclear factor-κB, tumor necrosis factor-alpha, interleukin-1 beta, and Interleukin-6 and significantly (p < 0.05) reduced levels/expression of serum/myocardial interleukin-10 in myocardial infarcted rats. Nevertheless, isoproterenol-induced rats treated with 3, 4-dihydroxybenzoic acid considerably (p < 0.05) attenuated all the biochemical, molecular, and IHC parameters investigated and inhibited oxidative stress and inflammation and protected the heart, through its antioxidant and anti-inflammatory mechanisms.

Phytoconstituents with cardioprotective properties: A pharmacological overview on their efficacy against myocardial infarction.

Myocardial infarction (MI) is considered one of the most common cardiac diseases and major cause of death worldwide. The prevalence of MI and MI-associated mortality have been increasing in recent years due to poor lifestyle habits viz. residency, obesity, stress, and pollution. Synthetic drugs for the treatment of MI provide good chance of survival; however, the demand to search more safe, effective, and natural drugs is increasing. Plants provide fruitful sources for powerful antioxidant and anti-inflammatory agents for prevention and/or treatment of MI. However, many plant extracts lack exact information about their possible dosage, toxicity and drug interactions which may hinder their usefulness as potential treatment options. Phytoconstituents play cardioprotective role by either acting as a prophylactic or adjuvant therapy to the concurrently used synthetic drugs to decrease the dosage or relief the side effects of such drugs. This review highlights the role of different herbal formulations, examples of plant extracts and types of several isolated phytoconstituents (phenolic acids, flavonoids, stilbenes, alkaloids, phenyl propanoids) in the prevention of MI with reported activities. Moreover, their possible mechanisms of action are also discussed to guide future research for the development of safer substitutes to manage MI.

Gynostemma pentaphyllum Makino exerts cardioprotective effects by improving hemodynamic, biochemical and histopathological changes through activation of PI3K signalling in isoproterenol-induced myocardial infarction in rats.

OBJECTIVES: To evaluate the cardioprotective effects of Gynostemma pentaphyllum Makino in isoproterenol-induced myocardial infarction in rats and to evaluate the role of phosphatidylinositol 3-kinases (PI3K) in cardioprotection. METHODS: The protective effect of the hydroalcoholic leaf extract of Gynostemma pentaphyllum (LEGP) on the heart was investigated against isoproterenol (ISO)-induced MI in rats. Preliminary phytochemical screening was performed followed by molecular docking. For the in vivo studies Wistar albino rats (Male) were divided among different groups. Different parameters were evaluated such as heart weight index, Electrocardiogram (ECG) analysis, triphenyl tetrazolium chloride assay, cardiac enzyme markers, oxidative stress, antioxidant enzymes, PI3K levels, and histopathology of cardiac tissue. RESULTS: Results showed that LEGP improved the electrocardiogram, reduced infarct size, and decreased the levels of cardiac enzyme markers and oxidative stress, while antioxidant enzymes and PI3K levels were increased. CONCLUSION: LEGP protected the heart against ISO-induced MI in rats by improving hemodynamic, biochemical and histological attributes. These protective effects were produced by the phytoconstituents of the LEGP through modulation of the PI3K signalling pathway.

ß stimulator induces upregulation of miR-27a in the rat heart one hour after the injection.

MicroRNAs (miRs) are non-coding small RNA containing 18 to 22 nucleotides, that post-transcriptionally regulates mRNA expression. Chronic injection of ß stimulator is known to induce cardiac injury and change of miRs expression level in the heart with some pathological changes such as fibrosis, heart failure, myocardial infarction. We investigated the changes in the expression level of miRs in the rat heart one hour after isoproterenol (a ß stimulator) injection. Male Sprague-Dawley rats were assigned into three groups and received subcutaneous injection of normal sarin (NS) or 0.1 mg/kg isoproterenol (ISO-0.1) or 10 mg/kg isoproterenol (ISO-10). After one hour, we collected their heart and plasma. Total RNA was extracted from the left ventricle and used for deep miRNA sequencing. Based on the results of miRNA sequencing, we performed real-time polymerase chain reaction (RT-PCR) using 8 miR primers. Cardiac injury was evaluated by hematoxylin and eosin, and phosphotungstic acid-hematoxylin staining and measuring troponin-I levels in plasma. Troponin-I was significantly increased in ISO-0.1 and ISO-10 groups, but histological observation did not show any cardiac necrosis. miRNA sequencing identified 14 upregulated miRs and 12 downregulated miRs. Of the 26 miRs, RT-PCR confirmed miR-144-3p/5p and miR-451-5p were decreased, and that 5 miRs (miR-27a-5p, miR-30b-3p, miR-92a-1-5p, miR-132-5p, miR-582-3p) were upregulated. This study showed that ß stimulus causes downregulation of miR-144/451 cluster and increases expression of five 5 miRs in the heart, especially 6.5-fold upregulation of miR-27a-5p as early as one hour after isoproterenol injection. Therefore, these miRs might be good biomarkers for cardiac injury.

Inhibition of Cholesteryl Ester Transfer Protein Contributes to the Protection of Ginsenoside Re Against Isoproterenol-Induced Cardiac Hypertrophy.

Background and objectives Ginsenoside Re (Re), a protopanaxatriol-type saponin extracted from ginseng, is known to have potential cardioprotective effects; however, the mechanisms of Re in improving cardiac hypertrophy have not been fully elucidated. This study aimed to investigate the therapeutic effects and underlying mechanism of Re on isoproterenol (ISO)-induced cardiac hypertrophy in vivo and in vitro. Methods Rats were intraperitoneally injected with ISO 30 mg/kg thrice daily for 14 consecutive days to induce cardiac hypertrophy, and these rats were treated with atorvastatin (ATC, 20 mg/kg) or Re (20 mg/kg or 40 mg/kg) once daily for three days in advance until the end of the experiment. Heart weight index, hematoxylin and eosin staining, and hypertrophy-related fetal gene expression were measured to evaluate the effect of Re on cardiac hypertrophy in vivo. Meanwhile, the rat H9c2 cardiomyocyte hypertrophy model was induced by ISO 10 µM for 24 hours. Cell surface area and hypertrophy-related fetal gene expression were determined to assess the effect of Re on ISO-induced cardiomyocyte hypertrophy in vitro. The levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) in both serum and cardiomyocytes were detected by enzymatic colorimetric assays. Furthermore, we chose cholesteryl ester transfer protein (CETP) as a target to explore the influence of Re on CETP expression in vivo and in vitro through real-time polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay. Results Intraperitoneal administration of ISO into rats resulted in increases in cross-sectional cardiomyocyte area, the ratio of heart weight to body weight, the ratio of left ventricular weight to body weight, and the ratio of right ventricular weight to body weight, as well as reactivation of fetal genes; however, treatment with Re or ATC ameliorated most of these hypertrophic responses. Similarly, Re pronouncedly alleviated ISO-induced cardiomyocyte hypertrophy, as evidenced by a decreased cell surface area and downregulation of fetal genes. Moreover, our in vivo and in vitro data revealed that Re reduced TC, TG, and LDL-C levels, and enhanced HDL-C levels. Re improved cardiac hypertrophy mainly associated with the inhibition of mRNA level and protein expression of CETP, to an extent comparable to that of the classical CETP inhibitor, anacetrapib. Conclusions Our research found that CETP inhibition contributes to the protection of Re against ISO-induced cardiac hypertrophy, which provides evidence for the application of Re for cardiovascular disease treatments.

Vernodalin Alleviates Cardiotoxicity and Inflammation in Isoproterenol-Mediated Myocardial Infarction through NF-κB/AMPK Signaling Pathways in Rats.

BACKGROUND: Myocardial infarction (MI) is the foremost cause of mortality in cardiovascular diseases. MI ultimately exacerbates cardiotoxicity due to the release of toxicity biomarkers and inflammatory infiltration. AIM: Vernodalin (VN) is a renowned cytotoxic sesquiterpene lactone that possesses antioxidant, anticancer, and anti-inflammatory properties. The cardioprotective mechanism of VN remains concealed. Hence, we explored the cardioprotective efficacy of VN on isoproterenol (ISO)- mediated MI and analyzed its underlying mechanism. METHODS: Wistar albino rats were injected ISO (85 mg/kg bw) subcutaneously to induce MI to evaluate the cardioprotective potential of VN (10 mg/kg bw) by assessing heart weight/ body weight index, hemodynamic, toxicity enzymes, histopathology, inflammatory mediators, and signaling pathway. ISO enhanced heart weight/body weight index, cardiotoxicity enzymes, biomarkers, inflammation, and histopathological changes while reducing hemodynamic parameters and VEGF-B, AMPK, and eNOS signaling pathways. RESULTS: Treatment with VN could significantly (p<0.05) mitigate the heart weight/body weight index, cardiotoxicity enzymes, biomarkers, inflammatory cytokines, and histopathological changes while enhancing hemodynamic parameters and VEGF-B, AMPK, and eNOS signaling pathways. Collectively, our findings revealed that the VN ameliorated defensive action against MI and averted myocardial injury by reducing the NF-κB-mediated inflammatory pathways in rats. CONCLUSION: These findings established that VN expressively preserves the myocardium and employs anti-inflammatory actions by regulating NF-κB, VEGF-B, AMPK, and eNOS signaling pathways.

ß2-adrenergic receptor activation decreases the mechanical sensitivity of rat masticatory muscle afferent fibres.

BACKGROUND: Activation of ß2 adrenergic receptors reduces cutaneous mechanical pain thresholds in rats. While ß2 adrenergic receptor activation may contribute to mechanisms that underlie temporomandibular joint pain, its effect on masticatory muscle pain sensitivity is uncertain. OBJECTIVES: The current study sought to determine the extent to which ß adrenergic receptors are expressed by masticatory muscle afferent fibres, and to assess the effect of local activation of these receptors on the mechanical sensitivity of masticatory muscle afferent fibres in rats. METHODS: Trigeminal ganglion neurons that innervate the rat (n = 12) masseter muscle and lower lip were identified by tissue injection of fluorescent dyes and were then stained with antibodies against ß1 or ß2 adrenergic receptors. Extracellular recordings from 60 trigeminal ganglion neurons that innervate the masticatory muscle were undertaken in a second group of anaesthetised rats of both sexes (n = 37) to assess afferent mechanical activation thresholds. Thresholds were assessed before and after injection of the ß adrenergic receptor agonists into masticatory muscle. RESULTS: ß1 and ß2 adrenergic receptor expression was greater in labial skin than in masticatory muscle ganglion neurons (p < .05, one-way ANOVA, Holm-Sidak test). There was a higher expression of ß2 adrenergic receptors in masticatory muscle ganglion neurons in males than in females. The mixed ß agonist isoproterenol increased afferent mechanical activation threshold in male but not female rats (p < .05, Mann-Whitney test). In male rats, salbutamol, a ß2 selective agonist, also increased afferent mechanical activation threshold but hydralazine, a vasodilator, did not (p < .05, Mann-Whitney test). CONCLUSION: Activation of ß2 adrenergic receptors decreases the mechanical sensitivity of masticatory muscle afferent fibres in a sex-related manner.

Isoproterenol improves hemodynamics and right ventricle-pulmonary artery coupling after heart transplantation.

Right ventricular failure (RVF) is a major cause of early mortality after heart transplantation (HT). Isoproterenol (Iso) has chronotropic, inotropic, and vasodilatory properties, which might improve right ventricle function in this setting. We aimed to investigate the hemodynamic effects of isoproterenol on patients with post-HT RVF. We conducted a 1-yr retrospective observational study including patients receiving isoproterenol (Iso) and dobutamine for early RVF after HT. A comprehensive multiparametric hemodynamic evaluation was performed successively three times: no isoproterenol, low doses: 0.025 µg/kg/min, and high doses: 0.05 µg/kg/min (henceforth, respectively, called no Iso, low Iso, and high Iso). From June 2022 to June 2023, 25 patients, median [interquartile range (IQR) 25-75] age 54 [38-61] yr, were included. Before isoproterenol was introduced, all patients received dobutamine, and 15 (60%) were on venoarterial extracorporeal membrane oxygenation (VA-ECMO). Isoproterenol significantly increased heart rate from 84 [77-99] (no Iso) to 91 [88-106] (low Iso) and 102 [90-122] beats/min (high Iso, P < 0.001). Similarly, cardiac index rose from 2.3 [1.4-3.1] to 2.7 [1.8-3.4] and 3 [1.9-3.7] L/min/m2 (P < 0.001) with a concomitant increase in indexed stroke volume (28 [17-34] to 31 [20-34] and 33 [23-35] mL/m2, P < 0.05). Effective pulmonary arterial elastance and pressures were not modified by isoproterenol. Pulmonary vascular resistance (PVR) tended to decrease from 2.9 [1.4-3.6] to 2.3 [1.3-3.5] wood units (WU), P = 0.06. Right ventricular ejection fraction/systolic pulmonary artery pressure (sPAP) evaluating right ventricle-pulmonary artery (RV-PA) coupling increased after isoproterenol from 0.8 to 0.9 and 1%·mmHg-1 (P = 0.001). In conclusion, in post-HT RVF, isoproterenol exhibits chronotropic and inotropic effects, thereby improving RV-PA coupling and resulting in a clinically relevant increase in the cardiac index.NEW & NOTEWORTHY This study offers a detailed and comprehensive hemodynamic investigation at the bedside, illustrating the favorable impact of isoproterenol on right ventricular-pulmonary arterial coupling and global hemodynamics. It elucidates the physiological effects of an underused inotropic strategy in a critical clinical scenario. By enhancing cardiac hemodynamics, isoproterenol has the potential to expedite right ventricular recovery and mitigate primary graft dysfunction, thereby reducing the duration of mechanical support and intensive care unit stay posttransplantation.

Melatonin improves nitric oxide bioavailability in isoproterenol induced myocardial injury.

Isoproterenol administration is associated with cardiac inflammation and decreased NO availability. Melatonin has been reported to have cardioprotective effect. The aim of this study was to investigate the effect of melatonin on NO bioavailability and inflammation in myocardial injury induced by isoproterenol. Isoproterenol was administrated in male Wistar rats for 7 days to induce cardiac injury. The animals were divided into 3 groups: Control, Isoproterenol, Isoproterenol + Melatonin. Animals received melatonin for 7 days. Echocardiographic analysis was performed and the hearts were collected for molecular analysis. Animals that received isoproterenol demonstrated a reduction in left ventricle systolic and diastolic diameter, indicating the presence of concentric hypertrophy. Melatonin was able to attenuate this alteration. Melatonin also improved NO bioavailability and decreased NF-κß, TNFα and IL-1ß expression. In conclusion, melatonin exhibited a cardioprotective effect which was associated with improving NO bioavailability and decreasing the pro-inflammatory proteins.

ß-Adrenergic Stimulation-Induced PVAT Dysfunction in Male Sex: A Role for 11ß-Hydroxysteroid Dehydrogenase-1.

Long-term ß-adrenoceptor (ß-AR) stimulation is a pathological mechanism associated with cardiovascular diseases resulting in endothelial and perivascular adipose tissue (PVAT) dysfunction. In this study, we aimed to identify whether ß-adrenergic signaling has a direct effect on PVAT. Thoracic aorta PVAT was obtained from male Wistar rats and cultured ex vivo with the ß-AR agonist isoproterenol (Iso; 1 µM) or vehicle for 24 hours. Conditioned culture medium (CCM) from Iso-treated PVAT induced a marked increase in aorta contractile response, induced oxidative stress, and reduced nitric oxide production in PVAT compared to vehicle. In addition, Iso-treated PVAT and PVAT-derived differentiated adipocytes exhibited higher corticosterone release and protein expression of 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1), an enzyme responsible for de novo synthesis of corticosterone. Macrophages exposed to Iso also exhibited increased corticosterone release in response to ß-AR stimulation. Incubation of Iso-treated PVAT and PVAT-derived differentiated adipocytes with ß3-AR antagonist restored aorta contractile function modulated by Iso-CCM and normalized 11ß-HSD1 protein expression. These results show that ß3-AR signaling leads to upregulation of 11ß-HSD1 in PVAT, thus increasing corticosterone release and contributing to impair the anticontractile function of this tissue.

Protective Effect of Prunetin on Isoproterenol-Induced Myocardial Infarction in Wistar Rats via Biochemical Characterization.

BACKGROUND: The development of MI following ischemia damage is influenced by oxidative stress. Myocardial Infarction (MI) generates myocardial ischemia injury, which damages the cardiomyocytes. Ischemia builds up to a critical level over time in MI, causing permanent myocardial cell damage or death. AIM: The current study sought to determine whether Prunetin (PRU) could protect against Isoproterenol (ISO)-induced cardiac heart failure in rats by examining cardiac diagnostic markers, lipid peroxidation products, enzymatic and non-enzymatic antioxidant levels, and histological changes. METHODS: PRU (20 mg/kg bwt) was orally administered for 19 days to rats, and after the treatment, ISO (85 mg/kg bwt) was subcutaneously administered with an intermission of 24 h for a couple of days to induce myocardial infarction on 20th and 21st days. ISO-treated rats exhibited considerable alterations in cardiac-sensitive markers in the serum. The levels of lipid peroxidation markers augmented drastically in the plasma and myocardium. Enzymatic antioxidant levels in erythrocytes and myocardium and the states of non-enzymatic antioxidants were diminished in the plasma and heart tissue of ISO-treated rats. The histopathological examination of heart tissue exhibited cardiac damage in ISO-induced rats. RESULTS: The oral administration of PRU significantly lowered the levels of lipid peroxidation and biochemical indicators, while significantly improving the antioxidant system function of ISO-interposed rats. In PRU-treated ISO-injected rats, histological examinations revealed suppressed myocardial destruction. CONCLUSION: Our research shows that oral pretreatment of PRU prevented ISO-induced oxidative stress in MI.

Impact of residual induction number of non-pulmonary vein foci on the 2-year outcomes in patients with paroxysmal atrial fibrillation.

BACKGROUND: Residual non-pulmonary vein (PV) foci are significantly associated with atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). However, we previously reported among patients with non-PV foci induced only once, none experienced AF recurrence. Thus, we aimed to investigate the correlation between the residual induction number of non-PV foci and ablation outcome in paroxysmal AF patients. METHODS AND RESULTS: We investigated 55 paroxysmal AF patients with residual non-PV foci after PVI and ablation of non-PV-foci. Study patients were classified into the residual one-time induction of non-PV foci (residual OTI-nPVF) group (n = 23) and residual repeatedly induced non-PV foci (residual RI-nPVF) group (n = 32). Furthermore, the residual RI-nPVF group was divided into the low inducibility group (n = 10) and high inducibility group (n = 22) according to the presence or absence of non-PV foci provoked by two sets of drug induction tests (non-PV foci inducibility). In addition, the latter was divided into the ablation group (n = 14) or observation group (n = 8). The 2-year AF recurrence-free rate in the residual RI-nPVF group was significantly lower compared to the residual OTI-nPVF group (53% vs. 90%, p = 0.018). There was no significant difference of the 2-year AF recurrence-free rates in the inducibility of non-PV foci (p = 0.913) and the presence or absence of ablation (p = 0.812) in the residual RI-nPVF group. CONCLUSIONS: Among paroxysmal AF patients, the presence of residual RI-nPVF was associated with higher AF recurrence compared to residual OTI-nPVF. Furthermore, within residual RI-nPVF subgroup, non-PV foci inducibility or ablation of some residual RI-nPVF did not affect ablation outcome.

Resveratrol-Based Liposomes Improve Cardiac Remodeling Induced by Isoproterenol Partially by Modulating MEF2, Cytochrome C and S100A1 Expression.

Isoproterenol (ISO), a chemically synthesized catecholamine, belongs to ß-adrenoceptor agonist used to treat bradycardia. The ß-adrenergic agonist is an essential regulator of myocardial metabolism and contractility; however, excessive exposure to ISO can initiate oxidative stress and inflammation. This study aims to investigate the molecular mechanisms underlying ISO-induced cardiac remodeling, the protective efficacy of resveratrol (RSVR), and its liposomal formulation (L-RSVR) against such cardiac change. Wistar albino rats were evenly divided into 4 groups. Control group, ISO group received ISO (50 mg/kg, s.c.) twice a week for 2 weeks, and RSVR- and L-RSVR-treated groups in which rats received either RSVR or L-RSVR (20 mg/kg/day, p.o.) along with ISO for 2 weeks. ISO caused a significant elevation of the expression levels of BAX and MEF2 mRNA, S100A1 and cytochrome C proteins, as well as DNA fragmentation in cardiac tissue compared to the control group. Treatment with either RSVR or L-RSVR for 14 days significantly ameliorated the damage induced by ISO, as evidenced by the improvement of all measured parameters. The present study shows that L-RSVR provides better cardio-protection against ISO-induced cardiac injury in rats, most likely through modulation of cardiac S100A1 protein expression and inhibition of inflammation and apoptosis.