Langendorff

We performed a comparative analysis of the effect of α2 -adrenoreceptor stimulation on the performance of Langendorff-isolated heart from rats with experimental myocardial infarction in the acute stage and sham-operated animals (control). In animals with peracute myocardial infarction, different agonist concentrations (clonidine, 10-6 and 10-9 M) produced a multidirectional effect on the left-ventricular developed pressure and speed and time parameters of heart contractility. In control rats, both concentrations of the agonist added to the perfused solution reduced contraction force...

OBJECTIVES: Cardiac arrest is a crucial procedure in various cardiac surgeries, during which the heart is subjected to an ischemic state. The occurrence of ischemia/reperfusion (I/R) injury is inevitable due to aortic blockage and opening. The Histidine-tryptophan-ketoglutarate (HTK) solution is commonly used as an organ protection liquid to mitigate cardiac injury during cardiac surgery. Despite its widespread use, there is significant potential for improving its protective efficacy...

Here we describe the acute myocardial effects of an elapid (red spitting cobra, Naja pallida) and a viper (western diamondback rattlesnake, Crotalus atrox) venom using an ex vivo heart model. Our results reveal two different pathophysiological trajectories that influence heart function and morphology. While cobra venom causes a drop in contractile force, rattlesnake venom causes enhanced contractility and frequency that coincides with differences in myocellular morphology. This highlights the medical complexity of snake venom-induced cardiotoxicity...

Hydrogen sulfide (H2 S), a gasotransmitter, plays a crucial role in vasorelaxation, anti-inflammatory processes and mitigating myocardial ischemia/reperfusion-induced injury by regulating various signaling processes. We designed a water soluble H2 S-releasing ascorbic acid derivative, BM-164, to combine the beneficial cardiovascular and anti-inflammatory effects of H2 S with the excellent water solubility and antioxidant properties of ascorbic acid. DPPH antioxidant assay revealed that the antioxidant activity of BM-164 in the presence of a myocardial tissue homogenate (extract) increased continuously over the 120 min test interval due to the continuous release of H2 S from BM-164...

Myoregulin is a recently discovered micropeptide that controls calcium levels by inhibiting the intracellular calcium pump sarco-endoplasmic reticulum Ca2+ -ATPase (SERCA). Keeping calcium levels balanced in the heart is essential for normal heart functioning, thus myoregulin has the potential to be a crucial regulator of cardiac muscle performance by reducing the rate of intracellular Ca2+ uptake. We provide the first report of myoregulin mRNA expression in human heart tissue, absence of expression in human plasma, and the effects of myoregulin on cardiac hemodynamics in an ex vivo Langendorff isolated rat heart model of ischemia/reperfusion...

Carbon nanomaterials possess antioxidant properties that can be applied in biomedicine and clinics for the development of new highly effective treatments against oxidative stress-induced diseases like ischemic heart disease. We previously reported the usage of graphene oxide (GrO) as a precursor for the elaboration of such prototypes. The promising findings led to the development of two new modifications of GrO: nitrogen-doped (N-GrO) and l-cysteine functionalized (S-GrO) derivatives as possible antioxidant agents in ischemia-reperfusion (I/R) conditions...

BACKGROUND: Scn5a heterozygous null (Scn5a+/- ) mice have historically been used to investigate arrhythmogenic mechanisms of diseases such as Brugada Syndrome and Lev's disease. Previously, we demonstrated that reducing ephaptic coupling (EpC) in ex vivo hearts exacerbates pharmacological Nav 1.5 loss of function (LOF). Whether this effect is consistent in a genetic Nav 1.5 LOF model is yet to be determined. We hypothesized that loss of EpC would result in greater reduction in conduction velocity (CV) for the Scn5a+/- mouse relative to wild type (WT)...

Synthetic cannabinoids become increasingly popular as a supposedly safe and legal alternative to cannabis. In order to circumvent the German New Psychoactive Substances Law, producers of so-called herbal mixtures rapidly design new substances with structural alterations that are not covered by the law. Acting as full agonists not only at the cannabinoid receptors 1 and 2, synthetic cannabinoids might have not only desired mental but also serious physical adverse effects. However, knowledge of adverse effects of specific substances is sparse and incomplete...

BACKGROUND: Metabolic syndrome (MetS) is associated with arrhythmias and cardiovascular mortality. Arrhythmogenesis in MetS results from atrial structural and electrical remodeling. OBJECTIVE: The small conductance Ca2+-activated K+ (SK) currents modulate atrial repolarization and may influence atrial arrhythmogenicity. This study investigated the regulation of SK current perturbed by a high-fat diet (HFD) to mimic MetS. METHODS: Thirty mice were divided into two groups that were fed with normal chow (CTL) and HFD for 4 months...

The pro-arrhythmic cardiac disorder catecholaminergic polymorphic ventricular tachycardia (CPVT) manifests as polymorphic ventricular tachycardia episodes following physical activity, stress, or catecholamine challenge, which can deteriorate into potentially fatal ventricular fibrillation. The mouse heart is a widespread species for modeling inherited cardiac arrhythmic diseases, including CPVT. Simultaneous optical mapping of transmembrane potential (Vm) and calcium transients (CaT) from Langendorff-perfused mouse hearts has the potential to elucidate mechanisms underlying arrhythmogenesis...

Mounting evidence suggests that cytochrome P450 epoxygenase-derived metabolites of docosahexaenoic acid, called epoxydocosapentaenoic acids (EDPs), limit mitochondrial damage after cardiac injury. In particular, the 19,20-EDP regioisomer has demonstrated potent cardioprotective action. Thus, we investigated our novel synthetic 19,20-EDP analog SA-22 for protection against cardiac ischemia-reperfusion (IR) injury. Isolated C57BL/6J mouse hearts were perfused through Langendorff apparatus for 20 minutes to obtain baseline function, followed by 30 minutes of global ischemia...

BACKGROUND: Intracellular Ca2+ cycling determines myocardial contraction and relaxation in response to physiological demands. SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+ -ATPase 2a) is responsible for the sequestration of cytosolic Ca2+ into intracellular stores during cardiac relaxation, and its activity is reversibly inhibited by PLN (phospholamban). However, the regulatory hierarchy of SERCA2a activity remains unclear. METHODS: Cardiomyocyte-specific ZBTB20 knockout mice were generated by crossing ZBTB20 flox mice with Myh6 -Cre mice...

BACKGROUND: The heart relies heavily on external fatty acid (FA) for energy production. VEGFB (vascular endothelial growth factor B) has been shown to promote endothelial FA uptake by upregulating FA transporters. However, its impact on LPL (lipoprotein lipase)-mediated lipolysis of lipoproteins, a major source of FA for cardiac use, is unknown. METHODS: VEGFB transgenic (Tg) rats were generated by using the α-myosin heavy chain promoter to drive cardiomyocyte-specific overexpression...

Dynamin-related protein 1 (Drp1) is a cytosolic GTPase protein that when activated translocates to the mitochondria, meditating mitochondrial fission and increasing reactive oxygen species (ROS) in cardiomyocytes. Drp1 has shown promise as a therapeutic target for reducing cardiac ischemia/reperfusion (IR) injury; however, the lack of specificity of some small molecule Drp1 inhibitors and the reliance on the use of Drp1 haploinsufficient hearts from older mice have left the role of Drp1 in IR in question. Here, we address these concerns using two approaches, using: (a) short-term (3 weeks), conditional, cardiomyocyte-specific, Drp1 knockout (KO) and (b) a novel, highly specific Drp1 GTPase inhibitor, Drpitor1a...

BACKGROUND: Although aging is known to be associated with an increased incidence of both atrial and ventricular arrhythmias, there is limited knowledge about how Schwann cells (SC) and the intracardiac nervous system (iCNS) remodel with age. Here we investigate the differences in cardiac SC, parasympathetic nerve fibers, and muscarinic acetylcholine receptor M2 (M2R) expression in young and old mice. Additionally, we examine age-related changes in cardiac responses to sympathomimetic and parasympathomimetic drugs...

The present study aims to design and fabricate a system capable of generating heterogeneities on the epicardial surface of an isolated rabbit heart perfused in a Langendorff system. The system consists of thermoelectric modules that can be independently controlled by the developed hardware, thereby allowing for the generation of temperature gradients on the epicardial surface, resulting in conduction slowing akin to heterogeneities of pathological origin. A comprehensive analysis of the system's viability was performed through modeling and thermal simulation, and its practicality was validated through preliminary tests conducted at the experimental cardiac electrophysiology laboratory of the University of Valencia...

OBJECTIVES: In myocardial infarction, the addition of mineralocorticoid receptor blockers to standard therapies, such as angiotensin-converting enzyme inhibitors or beta-blockers, reportedly reduces mortality and cardiac events. We investigated whether the non-steroidal mineralocorticoid receptor blocker esaxerenone has cardioprotective effects and its protective mechanisms. METHODS: Isolated rat hearts were Langendorff-perfused (constant pressure, 80 mmHg) with oxygenated Krebs-Henseleit bicarbonate buffer and reperfused for 60 min; afterwards, recovery of function (left ventricular pressure, measured with an intraventricular balloon) and myocardial injury were measured...

Heart failure is a leading cause of death and is often accompanied by activation of quiescent cardiac myofibroblasts, which results in cardiac fibrosis. In this study, we aimed to identify novel circular RNAs that regulate cardiac fibrosis. We applied transverse aortic constriction (TAC) for 1, 4, and 8 weeks in mice. RNA sequencing datasets were obtained from cardiac fibroblasts isolated by use of a Langendorff apparatus and then further processed by use of selection criteria such as differential expression and conservation in species...

Calcium signaling is a critical process required for cellular mechanisms such as cardiac contractility. The inability of the cell to properly activate or regulate calcium signaling can lead to contractile dysfunction. In isolated cardiomyocytes, calcium signaling has been primarily studied using calcium fluorescent dyes, however these dyes have limited applicability to whole organs. Here, we crossed the Salsa6f mouse which expresses a genetically encoded ratiometric cytosolic calcium indicator with a cardiomyocyte specific inducible cre to temporally-induce expression and studied cytosolic calcium transients in isolated cardiomyocytes and modified Langendorff heart preparations...

BACKGROUND: The Langendorff-perfused ex-vivo isolated heart model has been extensively used to study cardiac function for many years. However, electrical and mechanical function are often studied separately-despite growing proof of a complex electro-mechanical interaction in cardiac physiology and pathology. Therefore, we developed an isolated mouse heart perfusion system that allows simultaneous recording of electrical and mechanical function. METHODS: Isolated mouse hearts were mounted on a Langendorff setup and electrical function was assessed via a pseudo-ECG and an octapolar catheter inserted in the right atrium and ventricle...