RESUMEN
Hypercholesterolemia is one of the most important risk factors for cardiovascular diseases. However, it is mostly associated with vascular dysfunction and atherosclerotic lesions, while evidence of direct effects of hypercholesterolemia on cardiomyocytes and heart function is still incomplete and controversial. In this study, we assessed the direct effects of hypercholesterolemia on heart function and the electro-contractile properties of isolated cardiomyocytes. After 5 weeks, male Swiss mice fed with AIN-93 diet added with 1.25% cholesterol (CHO), developed an increase in total serum cholesterol levels and cardiomyocytes cholesterol content. These changes led to altered electrocardiographic records, with a shortening of the QT interval. Isolated cardiomyocytes displayed a shortening of the action potential duration with increased rate of depolarization, which was explained by increased IK, reduced ICa.L and altered INa voltage-dependent inactivation. Also, reduced diastolic [Ca2+]i was found with preserved adrenergic response and cellular contraction function. However, contraction of isolated hearts is impaired in isolated CHO hearts, before and after ischemia/reperfusion, although CHO heart was less susceptible to arrhythmic contractions. Overall, our results demonstrate that early hypercholesterolemia-driven increase in cellular cholesterol content is associated with direct modulation of the heart and cardiomyocytes' excitability, Ca2+ handling, and contraction.
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Hipercolesterolemia , Miocitos Cardíacos , Animales , Miocitos Cardíacos/metabolismo , Miocitos Cardíacos/patología , Hipercolesterolemia/fisiopatología , Hipercolesterolemia/metabolismo , Hipercolesterolemia/patología , Ratones , MasculinoRESUMEN
Clinical practice has benefited from new methodologies such as realistic simulation (RS). RS involves recreating lifelike scenarios to more accurately reflect real clinical practice, enhancing learners' skills and decision-making within controlled environments, and experiencing remarkable growth in medical education. However, RS requires substantial financial investments and infrastructure. Hence, it is essential to determine the effectiveness of RS in the development of skills among medical students, which will improve the allocation of resources while optimizing learning. This cross-sectional study was carried out in the simulation laboratory of a medical school, and the performance of students who underwent two different curriculum matrices (without RS and with RS, from 2021 to 2022) in the Advanced Cardiac Life Support (ACLS) course was compared. This test was chosen considering that the competencies involved in cardiac life support are essential, regardless of the medical specialty, and that ACLS is a set of life-saving protocols used worldwide. We observed that the impact of RS can be different for practical abilities when compared with the theoretical ones. There was no correlation between the general academic performance and students' grades reflecting the RS impact. We conclude that RS leads to less remediation and increased competence in practical skills. RS is an important learning strategy that allows repeating, reviewing, and discussing clinical practices without exposing the patient to risks.NEW & NOTEWORTHY Realistic simulation (RS) positively affected the performance of the students differently; it had more influence on practical abilities than theoretical knowledge. No correlation between the general academic performance and grades of the students without RS or with RS was found, providing evidence that RS is an important tool in Advanced Cardiac Life Support education.
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Apoyo Vital Cardíaco Avanzado , Estudiantes de Medicina , Humanos , Apoyo Vital Cardíaco Avanzado/educación , Estudios Transversales , Curriculum , Aprendizaje , Competencia ClínicaRESUMEN
The renin-angiotensin system (RAS) is a key hormonal system. In recent years, the functional analysis of the novel axis of the RAS (ACE2/Ang-(1-7)/Mas receptor) revealed that its activation can become protective against several pathologies, including cardiovascular diseases. Mas knockout mice (Mas-KO) represent an important tool for new investigations. Indeed, extensive biological research has focused on investigating the functional implications of Mas receptor deletion. However, although the Mas receptor was identified in neonatal cardiomyocytes and also in adult ventricular myocytes, only few reports have explored the Ang-(1-7)/Mas signaling directly in cardiomyocytes to date. This study investigated the implication of Mas receptor knockout to the cytokine profile, energy metabolism, and electrical properties of mice-isolated cardiomyocytes. Here, we demonstrated that Mas-KO mice have modulation in some cytokines, such as G-CSF, IL-6, IL-10, and VEGF in the left ventricle. This model also presents increased mitochondrial number in cardiomyocytes and a reduction in the myocyte diameter. Finally, Mas-KO cardiomyocytes have altered action potential modulation after diazoxide challenge. Such electrical finding was different from the data showed for the TGR(A1-7)3292 (TGR) model, which overexpresses Ang-(1-7) in the plasma by 4.5, used by us as a control. Collectively, our findings exemplify the importance of understanding the ACE2/Ang-(1-7)/Mas pathway in cardiomyocytes and heart tissue. The Mas-KO mice model can be considered an important tool for new RAS investigations.
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Enzima Convertidora de Angiotensina 2 , Miocitos Cardíacos , Potenciales de Acción , Angiotensina I/metabolismo , Animales , Citocinas/metabolismo , Ratones , Ratones Noqueados , Miocitos Cardíacos/metabolismo , Fragmentos de Péptidos/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Sistema Renina-Angiotensina/fisiologíaRESUMEN
Pyrethroids (PY) are synthetic pesticides used in many applications ranging from large-scale agriculture to household maintenance. Their classical mechanisms of action are associated with binding to the sodium channel of insect neurons, disrupting its inactivation, ensuring their use as insecticides. However, PY can also lead to toxicity in vertebrates, including humans. In most toxicological studies, the impact of PY on heart function is neglected. Acute exposure to a high dose of PY causes enhancement of the late sodium current (INaL), which impairs the action potential waveform and can cause severe cardiac arrhythmias. Moreover, long-term, low-dose exposure to PY displays oxidative stress in the heart, which could induce tissue remodeling and impairment. Isolated and preliminary evidence supports that, for acute exposure to PY, an antiarrhythmic therapy with ranolazine (an INaL blocker), can be a promising therapeutic approach. Besides, heart tissue remodeling associated with low doses and long-term exposure to PY seems to benefit from antioxidant therapy. Despite significant leaps in understanding the mechanical details of PY intoxication, currently, few studies are focusing on the heart. In this review, we present what is known and what are the gaps in the field of cardiotoxicity induced by PY.
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Cardiotoxicidad , Piretrinas , Animales , Humanos , Cardiotoxicidad/tratamiento farmacológico , Cardiotoxicidad/metabolismo , Piretrinas/toxicidad , Ranolazina , Bloqueadores de los Canales de Sodio/farmacología , Canales de Sodio/metabolismoRESUMEN
ß-Cyfluthrin, a class II Pyrethroid, is an insecticide used worldwide in agriculture, horticulture (field and protected crops), viticulture, and domestic applications. ß-Cyfluthrin may impair the function of biological systems; however, little information is available about its potential cardiotoxic effect. Here, we explored the acute toxicity of ß-Cyfluthrin in isolated heart preparations and its cellular basis, using isolated cardiomyocytes. Moreover, ß-Cyfluthrin effects on the sodium current, especially late sodium current (INa-L), were investigated using human embryonic kidney cells (HEK-293) cells transiently expressing human NaV1.5 channels. We report that ß-Cyfluthrin raised INa-L in a dose-dependent manner. ß-Cyfluthrin prolonged the repolarization of the action potential (AP) and triggered oscillations on its duration. Cardiomyocytes contraction and calcium dynamics were disrupted by the pesticide with a marked incidence of non-electronic-stimulated contractions. The antiarrhythmic drug Ranolazine was able to reverse most of the phenotypes observed in isolated cells. Lastly, ventricular premature beats (VPBs) and long QT intervals were found during ß-Cyfluthrin exposure, and Ranolazine was able to attenuate them. Overall, we demonstrated that ß-Cyfluthrin can cause significant cardiac alterations and Ranolazine ameliorated the phenotype. Understanding the insecticides' impacts upon electromechanical properties of the heart is important for the development of therapeutic approaches to treat cases of pesticides intoxication.
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Insecticidas , Piretrinas , Potenciales de Acción , Cardiotoxicidad/tratamiento farmacológico , Cardiotoxicidad/etiología , Células HEK293 , Humanos , Insecticidas/toxicidad , Miocitos Cardíacos , Nitrilos , Fenotipo , Piretrinas/farmacología , Ranolazina/farmacología , Sodio , Bloqueadores de los Canales de Sodio/farmacología , Bloqueadores de los Canales de Sodio/uso terapéuticoRESUMEN
Chagasic cardiomyopathy (CCC) is one of the main causes of heart failure and sudden death in Latin America. To date, there is no available medication to prevent or reverse the onset of cardiac symptoms. CCC occurs in a scenario of disrupted calcium dynamics and enhanced oxidative stress, which combined, may favor the hyper activation of calcium/calmodulin (Ca2+ /CaM)-calcium/calmodulin-dependent protein kinase II (CaMKII) (Ca2+ /CaM-CaMKII) pathway, which is fundamental for heart physiology and it is implicated in other cardiac diseases. Here, we evaluated the association between Ca2+ /CaM-CaMKII in the electro-mechanical (dys)function of the heart in the early stage of chronic experimental Trypanosoma cruzi infection. We observed that in vitro and ex vivo inhibition of Ca2+ /CaM-CaMKII reversed the arrhythmic profile of isolated hearts and isolated left-ventricles cardiomyocytes. The benefits of the limited Ca2+ /CaM-CaMKII activation to cardiomyocytes' electrical properties are partially related to the restoration of Ca2+ dynamics in a damaged cellular environment created after T. cruzi infection. Moreover, Ca2+ /CaM-CaMKII inhibition prevented the onset of arrhythmic contractions on isolated heart preparations of chagasic mice and restored the responsiveness to the increase in the left-ventricle pre-load. Taken together, our data provide the first experimental evidence for the potential of targeting Ca2+ /CaM-CaMKII pathway as a novel therapeutic target to treat CCC.
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Arritmias Cardíacas/metabolismo , Señalización del Calcio , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/metabolismo , Calcio/metabolismo , Calmodulina/metabolismo , Cardiomiopatía Chagásica/metabolismo , Trypanosoma cruzi/metabolismo , Animales , Arritmias Cardíacas/parasitología , Cardiomiopatía Chagásica/parasitología , Modelos Animales de Enfermedad , Masculino , Ratones , Ratones Endogámicos BALB CRESUMEN
NEW FINDINGS: What is the central question of this study? We investigated the effects of intrathecal administration of a novel toxin, CTK 01512-2, in a mouse model of Huntington's disease. We asked whether spinal cord neurons can represent a therapeutic target, given that the spinal cord seems to be involved in motor symptoms of Huntington's disease. Pharmacological approaches focusing on the spinal cord and skeletal muscles might represent a more feasible strategy than a high-risk brain intervention. What is the main finding and its importance? We provided evidence of a novel, local, neuroprotective effect of CTK 01512-2, paving a path for the development of approaches to treat motor symptoms of Huntington's disease beyond the brain. ABSTRACT: Phα1ß is a neurotoxin from the venom of the Phoneutria nigriventer spider, available as CTK 01512-2, a recombinant peptide. Owing to its antinociceptive and analgesic properties, CTK 01512-2 has been described to alleviate neuroinflammatory responses. Despite the diverse actions of CTK 01512-2 on the nervous system, little is known regarding its neuroprotective effect, especially in neurodegenerative conditions such as Huntington's disease (HD), a genetic movement disorder without cure. Here, we investigated whether CTK 01512-2 has a neuroprotective effect in a mouse model of HD. We hypothesized that spinal cord neurons might represent a therapeutic target, because the spinal cord seems to be involved in the motor symptoms of HD (BACHD) mice. We treated BACHD mice with CTK 01512-2 by intrathecal injection and performed in vivo motor behavioural and morphological analyses in the CNS (brain and spinal cord) and muscles. Our data showed that intrathecal injection of CTK 01512-2 significantly improved motor performance in the open field task. CTK 01512-2 protected neurons in the spinal cord (but not in the brain) from death, suggesting a local effect. CTK 01512-2 exerted its neuroprotective effect by inhibiting BACHD neuronal apoptosis, as revealed by a reduction in caspase-3 in the spinal cord. CTK 01512-2 was also able to revert BACHD muscle atrophy. In conclusion, our data suggest a novel role for CTK 01512-2 acting directly in the spinal cord to ameliorate morphofunctional aspects of spinal cord neurons and muscles and improve the performance of BACHD mice in motor behavioural tests. Given that HD shares similar symptoms with many neurodegenerative conditions, the findings presented herein might also be applicable to other disorders.
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Enfermedad de Huntington , Fármacos Neuroprotectores , Animales , Modelos Animales de Enfermedad , Enfermedad de Huntington/tratamiento farmacológico , Enfermedad de Huntington/genética , Ratones , Ratones Transgénicos , Neuronas , Fármacos Neuroprotectores/farmacología , Médula EspinalRESUMEN
The Renin-Angiotensin System (RAS) is expressed in the central nervous system and has important functions that go beyond blood pressure regulation. Clinical and experimental studies have suggested that alterations in the brain RAS contribute to the development and progression of neurodegenerative diseases. However, there is limited information regarding the involvement of RAS components in Huntington's disease (HD). Herein, we used the HD murine model, (BACHD), as well as samples from patients with HD to investigate the role of both the classical and alternative axes of RAS in HD pathophysiology. BACHD mice displayed worse motor performance in different behavioral tests alongside a decrease in the levels and activity of the components of the RAS alternative axis ACE2, Ang-(1-7), and Mas receptors in the striatum, prefrontal cortex, and hippocampus. BACHD mice also displayed a significant increase in mRNA expression of the AT1 receptor, a component of the RAS classical arm, in these key brain regions. Moreover, patients with manifest HD presented higher plasma levels of Ang-(1-7). No significant changes were found in the levels of ACE, ACE2, and Ang II. Our findings provided the first evidence that an imbalance in the RAS classical and counter-regulatory arms may play a role in HD pathophysiology.
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Angiotensina I , Enzima Convertidora de Angiotensina 2 , Enfermedad de Huntington , Fragmentos de Péptidos , Receptor de Angiotensina Tipo 1 , Sistema Renina-Angiotensina , Angiotensina I/genética , Angiotensina I/metabolismo , Angiotensina II/metabolismo , Enzima Convertidora de Angiotensina 2/genética , Animales , Modelos Animales de Enfermedad , Humanos , Enfermedad de Huntington/genética , Ratones , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Receptor de Angiotensina Tipo 1/genética , Receptor de Angiotensina Tipo 1/metabolismo , Sistema Renina-Angiotensina/genética , Sistema Renina-Angiotensina/fisiologíaRESUMEN
Diminazene aceturate (DIZE) is an anti-protozoan compound that has been previously reported to increase the activity of the angiotensin-converting enzyme 2 (ACE2) and thus increase Angiotensin-(1-7) production, leading to cardioprotection against post-myocardial infarction dysfunction and structural remodelling. Moreover, DIZE is able to ameliorate morpho-functional changes after myocardial infarction by enhancing ACE2 activity, thus increasing Angiotensin-(1-7) production (a benefic peptide of the renin-angiotensin system). However, despite the improvement in cardiac function/structure, little is known about DIZE effects on arrhythmia suppression, contraction/excitable aspects of the heart and importantly its mechanisms of action. Thus, our aim was to test the acute effect of DIZE cardioprotection at the specific level of potential antiarrhythmic effects and modulation in excitation-contraction coupling. For this, we performed in vitro and in vivo techniques for arrhythmia induction followed by an acute administration of DIZE. For the first time, we described that DIZE can reduce arrhythmias which is explained by modulation of cardiomyocyte contraction and excitability. Such effects were independent of Mas receptor and nitric oxide release. Development of a new DIZE-based approach to ameliorate myocardial contractile and electrophysiological dysfunction requires further investigation; however, DIZE may provide the basis for a future beneficial therapy to post-myocardial infarction patients.
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Antiarrítmicos/uso terapéutico , Arritmias Cardíacas/tratamiento farmacológico , Diminazeno/análogos & derivados , Miocitos Cardíacos/efectos de los fármacos , Animales , Antiarrítmicos/farmacología , Arritmias Cardíacas/fisiopatología , Diminazeno/farmacología , Diminazeno/uso terapéutico , Masculino , Ratones , Ratones Endogámicos C57BL , Miocitos Cardíacos/fisiología , Técnicas de Placa-Clamp/métodos , Ratas , Ratas WistarRESUMEN
Neurodegenerative diseases are associated with diverse symptoms, both motor and mental. Genetic and environmental factors can trigger neurodegenerative diseases. Chemicals as pesticides are constantly used in agriculture and also domestically. In this regard, pyrethroids (PY), are a class of insecticides in which its main mechanism of action is through disruption of voltage-dependent sodium channels function in insects. However, in mammals, they can also induce oxidative stress and enzyme dysfunction. This review investigates the association between PY and neurodegenerative diseases as Alzheimer's, Huntington's, Parkinson's, Amyotrophic Lateral Sclerosis, and Autism in animal models and humans. Published works using specific and non-specific models for these diseases were selected. We showed a tendency toward the development and/or aggravating of these neurodegenerative diseases following exposure to PYs. In animal models, the biochemical mechanisms of the diseases and their interaction with the insecticides are more deeply investigated. Nonetheless, only a few studies considered the specific model for each type of disease to analyze the impacts of the exposure. The choice of a specific model during the research is an important step and our review highlights the knowledge gaps of PYs effects using these models reinforcing the importance of them during the design of the experiments.
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Insecticidas , Enfermedades Neurodegenerativas , Síndromes de Neurotoxicidad , Plaguicidas , Piretrinas , Animales , Humanos , Piretrinas/toxicidad , Insecticidas/toxicidad , Enfermedades Neurodegenerativas/inducido químicamente , Plaguicidas/toxicidad , MamíferosRESUMEN
Tebuconazole (TEB), a widely used pesticide in agriculture to combat fungal infections, is commonly detected in global food, potable water, groundwater, and human urine samples. Despite its known in vivo toxicity, its impact on heart function remains unclear. In a 28-day study on male Wistar rats (approximately 100 g), administering 10 mg/kg/day TEB or a vehicle (control) revealed no effect on body weight gain or heart weight, but an increase in the infarct area in TEB-treated animals. Notably, TEB induced time-dependent changes in in vivo electrocardiograms, particularly prolonging the QT interval after 28 days of administration. Isolated left ventricular cardiomyocytes exposed to TEB exhibited lengthened action potentials and reduced transient outward potassium current. TEB also increased reactive oxygen species (ROS) production in these cardiomyocytes, a phenomenon reversed by N-acetylcysteine (NAC). Furthermore, TEB-treated animals, when subjected to an in vivo dobutamine (Dob) and caffeine (Caf) challenge, displayed heightened susceptibility to severe arrhythmias, a phenotype prevented by NAC. In conclusion, TEB at the no observed adverse effect level (NOAEL) dose adversely affects heart electrical function, increases arrhythmic susceptibility, partially through ROS overproduction, and this phenotype is reversible by scavenging ROS with NAC.
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Arritmias Cardíacas , Dobutamina , Triazoles , Humanos , Ratas , Animales , Masculino , Especies Reactivas de Oxígeno , Ratas Wistar , Arritmias Cardíacas/inducido químicamente , Acetilcisteína , Miocitos CardíacosRESUMEN
The TASK-1 channel belongs to the two-pore domain potassium channel family. It is expressed in several cells of the heart, including the right atrial (RA) cardiomyocytes and the sinus node, and TASK-1 channel has been implicated in the pathogenesis of atrial arrhythmias (AA). Thus, using the rat model of monocrotaline-induced pulmonary hypertension (MCT-PH), we explored the involvement of TASK-1 in AA. Four-week-old male Wistar rats were injected with 50 mg/kg of MCT to induce MCT-PH and isolated RA function was studied 14 days later. Additionally, isolated RA from six-week-old male Wistar rats were used to explore the ability of ML365, a selective blocker of TASK-1, to modulate RA function. The hearts developed right atrial and ventricular hypertrophy, inflammatory infiltrate and the surface ECG demonstrated increased P wave duration and QT interval, which are markers of MCT-PH. The isolated RA from the MCT animals showed enhanced chronotropism, faster contraction and relaxation kinetics, and a higher sensibility to extracellular acidification. However, the addition of ML365 to extracellular media was not able to restore the phenotype. Using a burst pacing protocol, the RA from MCT animals were more susceptible to develop AA, and simultaneous administration of carbachol and ML365 enhanced AA, suggesting the involvement of TASK-1 in AA induced by MCT. TASK-1 does not play a key role in the chronotropism and inotropism of healthy and diseased RA; however, it may play a role in AA in the MCT-PH model.
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Fibrilación Atrial , Hipertensión Pulmonar , Animales , Masculino , Ratas , Atrios Cardíacos/patología , Hipertensión Pulmonar/inducido químicamente , Hipertensión Pulmonar/patología , Hipertrofia Ventricular Derecha/inducido químicamente , Hipertrofia Ventricular Derecha/patología , Modelos Teóricos , Monocrotalina/efectos adversos , Ratas WistarRESUMEN
Tebuconazole (TEB) is an important fungicide that belongs to the triazole family. It is widely used in agriculture and its use has experienced a tremendous increase in the last decade. The long-term exposure of humans to this pesticide is a real threat because it is stable in water and soil. The association between long-term exposure to TEB and damage of several biological systems, including hepatotoxicity and cardiotoxicity is evident, however, acute toxicological studies to reveal the toxicity of TEB are limited. This research paper addressed the acute exposure of TEB in murine hearts, cardiomyocytes, and human cardiomyocytes derived from an induced pluripotent stem cell (hiPSC-CMs), spelling out TEB's impact on electromechanical properties of the cardiac tissue. In ex vivo experiments, TEB dose dependently, caused significant electrocardiogram (ECG) remodeling with prolonged PR and QTc interval duration. The TEB was also able to change the action potential waveform in murine cardiomyocytes and hiPSC-CMs. These effects were associated with the ability of the compound to block the L-type calcium current (IC50 = 33.2 ± 7.4 µmol.l-1) and total outward potassium current (IC50 = 5.7 ± 1.5 µmol.l-1). TEB also increased the sodium/calcium exchanger current in its forward and reverse modes. Additionally, sarcomere shortening and calcium transient in isolated cardiomyocytes were enhanced when cells were exposed to TEB at 30 µmol.l-1. Combined, our results demonstrated that acute TEB exposure affects the cardiomyocyte's electro-contractile properties and triggers the appearance of ECG abnormalities.
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Potenciales de Acción/efectos de los fármacos , Arritmias Cardíacas/inducido químicamente , Cardiotoxicidad/etiología , Fungicidas Industriales/toxicidad , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Triazoles/toxicidad , Animales , Modelos Animales de Enfermedad , Humanos , Ratones , Ratones Endogámicos C57BLRESUMEN
Chagas disease (CD) is caused by the parasitic protozoan T. cruzi. The progression of CD in ~30% of patients results in Chagasic Cardiomyopathy (CCM). Currently, it is known that the inflammatory system plays a significant role in the CCM. Interferon-gamma (IFN-γ) is the major cytokine involved in parasitemia control but has also been linked to CCM. The L-type calcium current (ICa,L) is crucial in the excitation/contraction coupling in cardiomyocytes. Thus, we compared ICa,L and the mechanical properties of cardiomyocytes isolated from infected wild type (WT) and IFN-γ(-/-) mice in the first stage of T. cruzi infection. Using the patch clamp technique, we demonstrated that the infection attenuated ICa,L in isolated cardiomyocytes from the right and left ventricles of WT mice at 15 days post-infection (dpi), which was not observed in the IFN-γ(-/-) cardiomyocytes. However, ICa,L was attenuated between 26 and 30 dpi in both experimental groups. Interestingly, the same profile was observed in the context of the mechanical properties of isolated cardiomyocytes from both experimental groups. Simultaneously, we tracked the mortality and MCP-1, TNF-α, IL-12, IL-6, and IL-10 serum levels in the infected groups. Importantly, the IFN-γ(-/-) and WT mice presented similar parasitemia and serum inflammatory markers at 10 dpi, indicating that the modifications in the cardiomyocyte functions observed at 15 dpi were directly associated with IFN-γ(-/-) deficiency. Thus, we showed that IFN-γ plays a crucial role in the electromechanical remodeling of cardiomyocytes during experimental T. cruzi infection in mice.
RESUMEN
This study aimed to investigate whether the Diminazene Aceturate (DIZE), an angiotensin-converting enzyme 2 (ACE2) activator, can revert cardiac dysfunction in ischemia reperfusion-induced (I/R) injury in animals and examine the mechanism underlying this effect. Wistar rats systemically received DIZE (1 mg/kg) for thirty days. Cardiac function in isolated rat hearts was evaluated using the Langendorff technique. After I/R, ventricular non-I/R and I/R samples were used to evaluate ATP levels. Mitochondrial function was assessed using cardiac permeabilized fibers and isolated cardiac mitochondria. Cardiac cellular electrophysiology was evaluated using the patch clamp technique. DIZE protected the heart after I/R from arrhythmia and cardiac dysfunction by preserving ATP levels, independently of any change in coronary flow and heart rate. DIZE improved mitochondrial function, increasing the capacity for generating ATP and reducing proton leak without changing the specific citrate synthase activity. The activation of the ACE2 remodeled cardiac electrical profiles, shortening the cardiac action potential duration at 90 % repolarization. Additionally, cardiomyocytes from DIZE-treated animals exhibited reduced sensibility to diazoxide (KATP agonist) and a higher KATP current compared to the controls. DIZE was able to improve mitochondrial function and modulate cardiac electrical variables with a cardio-protective profile, resulting in direct myocardial cell protection from I/R injury.
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Enzima Convertidora de Angiotensina 2 , Daño por Reperfusión , Adenosina Trifosfato , Animales , Arritmias Cardíacas , Diminazeno/análogos & derivados , Miocitos Cardíacos , Peptidil-Dipeptidasa A , Ratas , Ratas Wistar , ReperfusiónRESUMEN
BACKGROUND: Chagas disease (CD) is a neglected disease that induces heart failure and arrhythmias in approximately 30% of patients during the chronic phase of the disease. Despite major efforts to understand the cellular pathophysiology of CD there are still relevant open questions to be addressed. In the present investigation we aimed to evaluate the contribution of the Na+/Ca2+ exchanger (NCX) in the electrical remodeling of isolated cardiomyocytes from an experimental murine model of chronic CD. METHODOLOGY/PRINCIPAL FINDINGS: Male C57BL/6 mice were infected with Colombian strain of Trypanosoma cruzi. Experiments were conducted in isolated left ventricular cardiomyocytes from mice 180-200 days post-infection and with age-matched controls. Whole-cell patch-clamp technique was used to measure cellular excitability and Real-time PCR for parasite detection. In current-clamp experiments, we found that action potential (AP) repolarization was prolonged in cardiomyocytes from chagasic mice paced at 0.2 and 1 Hz. After-depolarizations, both subthreshold and with spontaneous APs events, were more evident in the chronic phase of experimental CD. In voltage-clamp experiments, pause-induced spontaneous activity with the presence of diastolic transient inward current was enhanced in chagasic cardiomyocytes. AP waveform disturbances and diastolic transient inward current were largely attenuated in chagasic cardiomyocytes exposed to Ni2+ or SEA0400. CONCLUSIONS/SIGNIFICANCE: The present study is the first to describe NCX as a cellular arrhythmogenic substrate in chagasic cardiomyocytes. Our data suggest that NCX could be relevant to further understanding of arrhythmogenesis in the chronic phase of experimental CD and blocking NCX may be a new therapeutic strategy to treat arrhythmias in this condition.
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Arritmias Cardíacas/patología , Cardiomiopatía Chagásica/patología , Potenciales de Acción , Compuestos de Anilina/farmacología , Animales , Calcio/metabolismo , Fenómenos Electrofisiológicos , Regulación de la Expresión Génica/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Miocitos Cardíacos/patología , Enfermedades Desatendidas , Níquel/farmacología , Técnicas de Placa-Clamp , Éteres Fenílicos/farmacología , Retículo Sarcoplasmático/metabolismo , Intercambiador de Sodio-Calcio/metabolismoRESUMEN
Motoneurons (MNs) control muscle activity by releasing the neurotransmitter acetylcholine (ACh) at the level of neuromuscular junctions. ACh is packaged into synaptic vesicles by the vesicular ACh transporter (VAChT), and disruptions in its release can impair muscle contraction, as seen in congenital myasthenic syndromes (CMS). Recently, VAChT gene mutations were identified in humans displaying varying degrees of myasthenia. Moreover, mice with a global deficiency in VAChT expression display several characteristics of CMS. Despite these findings, little is known about how a long-term decrease in VAChT expression in vivo affects MNs structure and function. Using Cre-loxP technology, we generated a mouse model where VAChT is deleted in select groups of MNs (mnVAChT-KD). Molecular analysis revealed that the VAChT deletion was specific to MNs and affected approximately 50% of its population in the brainstem and spinal cord, with alpha-MNs primarily targeted (70% in spinal cord). Within each animal, the cell body area of VAChT-deleted MNs was significantly smaller compared to MNs with VAChT preserved. Likewise, muscles innervated by VAChT-deleted MNs showed atrophy while muscles innervated by VAChT-containing neurons appeared normal. In addition, mnVAChT KD mice had decreased muscle strength, were hypoactive, leaner and exhibited kyphosis. This neuromuscular dysfunction was evident at 2 months of age and became progressively worse by 6 months. Treatment of mutants with a cholinesterase inhibitor was able to improve some of the motor deficits. As these observations mimic what is seen in CMS, this new line could be valuable for assessing the efficacy of potential CMS drugs.
Asunto(s)
Acetilcolina/genética , Neuronas Motoras/metabolismo , Síndromes Miasténicos Congénitos/genética , Proteínas de Transporte Vesicular de Acetilcolina/genética , Acetilcolina/metabolismo , Animales , Modelos Animales de Enfermedad , Humanos , Ratones , Neuronas Motoras/patología , Contracción Muscular/genética , Contracción Muscular/fisiología , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiología , Síndromes Miasténicos Congénitos/metabolismo , Síndromes Miasténicos Congénitos/patología , Unión Neuromuscular/genética , Unión Neuromuscular/metabolismo , Neurotransmisores/genética , Médula Espinal/metabolismo , Médula Espinal/fisiología , Transmisión Sináptica/genética , Vesículas Sinápticas/metabolismoRESUMEN
Abnormal calcium influx and glutamatergic excitotoxicity have been extensively associated with neuronal death in Huntington's disease (HD), a genetic movement disorder. Currently, there is no effective treatment for this fatal condition. The neurotoxin Phα1ß has demonstrated therapeutic effects as a calcium channel blocker, for example during pain control. However, little is known about its neuroprotective effect in HD. Herein, we investigated if Phα1ß is effective in inhibiting neuronal cell death in the BACHD mouse model for HD. We performed intrastriatal injection of Phα1ß in WT and BACHD mice. No side effects or unusual behaviors were observed upon Phα1ß administration. Using three different motor behavior tests, we observed that injection of the toxin in BACHD mice greatly improved the animals' motor-force as seen in the Wire-hang test, and also the locomotor performance, according to the Open field test. NeuN labeling for mature neuron detection revealed that Phα1ß toxin promoted neuronal preservation in the striatum and cortex, when injected locally. Intrastriatal injection of Phα1ß was not able to preserve neurons from the spinal cord and also not revert muscle atrophy in BACHD mice. Finally, we observed that Phα1ß might, at least in part, exert its protective effect by decreasing L-glutamate, measured in cerebrospinal fluid. Our data provide evidence of a novel neuroprotector effect of Phα1ß, paving a path for the development of new approaches to treat HD motor symptoms.
Asunto(s)
Enfermedad de Huntington/tratamiento farmacológico , Fármacos Neuroprotectores/administración & dosificación , Venenos de Araña/administración & dosificación , Animales , Modelos Animales de Enfermedad , Ácido Glutámico/metabolismo , Enfermedad de Huntington/patología , Ratones , Ratones Transgénicos , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patología , Neuronas/efectos de los fármacos , Médula Espinal/efectos de los fármacos , Médula Espinal/patologíaRESUMEN
The sympathetic nervous system is essential for maintenance of cardiac function via activation of post-junctional adrenergic receptors. Prolonged adrenergic receptor activation, however, has deleterious long-term effects leading to hypertrophy and the development of heart failure. Here we investigate the effect of chronic adrenergic receptors activation on excitation-contraction coupling (ECC) in ventricular cardiomyocytes from a previously characterized mouse model of chronic sympathetic hyperactivity, which are genetically deficient in the adrenoceptor α2A and α2C genes (ARDKO). When compared to wild-type (WT) cardiomyocytes, ARDKO displayed reduced fractional shortening (~33%) and slower relaxation (~20%). Furthermore, ARDKO cells exhibited several electrophysiological changes such as action potential (AP) prolongation (~50%), reduced L-type calcium channel (LCC) current (~33%), reduced outward potassium (K+) currents (~30%), and increased sodium/calcium exchanger (NCX) activity (~52%). Consistent with reduced contractility and calcium (Ca2+) currents, the cytosolic Ca2+ ([Ca2+]i) transient from ARDKO animals was smaller and decayed slower. Importantly, no changes were observed in membrane resting potential, AP amplitude, or the inward K+ current. Finally, we modified our existing cardiac ECC computational model to account for changes in the ARDKO heart. Simulations suggest that cellular changes in the ARDKO heart resulted in variable and dyssynchronous Ca2+-induced Ca2+ release therefore altering [Ca2+]i transient dynamics and reducing force generation. In conclusion, chronic sympathetic hyperactivity impairs ECC by changing the density of several ionic currents (and thus AP repolarization) causing altered Ca2+ dynamics and contractile activity. This demonstrates the important role of ECC remodeling in the cardiac dysfunction secondary to chronic sympathetic activity.
Asunto(s)
Electrofisiología Cardíaca , Acoplamiento Excitación-Contracción , Cardiopatías/fisiopatología , Sistema Nervioso Simpático/fisiopatología , Algoritmos , Animales , Calcio/metabolismo , Señalización del Calcio , Técnica del Anticuerpo Fluorescente , Cardiopatías/etiología , Cardiopatías/metabolismo , Ratones , Modelos Biológicos , Miocardio/metabolismo , Miocitos Cardíacos/metabolismo , Retículo Sarcoplasmático/metabolismoRESUMEN
Huntington's disease (HD) is a neurodegenerative disease caused by a CAG repeat expansion in the gene encoding the huntingtin protein (HTT). This expansion leads to the formation of mutant huntingtin protein (mHTT) that is expressed in many body tissue cells. The mHTT interacts with several molecular pathways within different cell types, affecting the regulation of the immune system cells. It is still very limited the understanding of the immune changes in peripheral tissues in HD. Herein, we investigated the levels of inflammatory and regulatory cytokines in peripheral organs (i.e. kidney, heart, liver and spleen) of the 12-month-old BACHD model of HD. This robust murine model closely resembles the human disease. We found significant changes in cytokine levels in all organs analyzed. Increased levels of IL-6 were found in the kidney, while levels of IL-6 and IL-12p70 were increased in the heart of BACHD mice in comparison with wild-type (WT) animals. In the liver, we observed enhanced IL-12p70 and TNF-α levels. In the spleen, there was an increase in the levels of IL-4 and a decrease in the levels of IL-5 and IL-6 in BACHD compared to WT. Our findings provide the first evidence that the BACHD model also exhibits immune changes in peripheral organs, opening an avenue for the investigation of the potential role played by peripheral inflammatory response in HD. Further studies are needed to systematically address the mechanisms and pathways underlying immune signaling in peripheral organs in HD.