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The coronavirus disease 2019 (COVID-19) pandemic has rapidly spread all over the world in the past several months. No effective treatment for COVID-19 has been established. High transmissibility and considerable mortality rates have forced many national governments to implement quarantine measures. Many patients with cancer rely on clinical trials to receive their oncologic care, but the routine conduct of clinical trials has substantially changed because of the COVID-19 pandemic. The oncology research community should implement formal policies based on the guidance given from regulatory agencies, with the goal of minimizing the risks of COVID-19 infection while maintaining appropriate oncologic treatments for patients during this pandemic.

A regiao Centro-Oeste brasileira destaca-se pela expansao da fronteira agricola e importantes avancos tecnologicos como agentes do crescimento da moderna agropecuaria, gerando preocupacao em termos de conservacao da biodiversidade. Aliado a isto, ressalta-se que os anfibios sao o grupo de vertebrados mais ameacados do mundo, sofrendo um acentuado declinio, sendo a perda e fragmentacao de habitat consideradas as principais causas de extincao. Neste cenario, analisar as tendencias na producao cientifica e um metodo util para maximizar os esforcos de conservacao. Neste estudo, foi realizada uma analise cienciometrica sobre anuros na regiao Centro-Oeste do Brasil para determinar lacunas e tendencias na producao cientifica. Os dados evidenciaram aumento significativo no numero de publicacoes nos ultimos 18 anos. Entretanto, os resultados indicaram a preferencia dos pesquisadores por determinadas areas do conhecimento, evidenciando um maior numero de pesquisas sobre historia natural, taxonomia e inventarios, nessa ordem, apresentando um padrao de incompletude na producao de conhecimento para esse grupo taxonomico. Destacamos a necessidade de alocacoes de esforcos de pesquisas em diferentes areas do conhecimento, principalmente em estudos sobre dinâmica populacional e morfologia, ampliando o conhecimento cientifico sobre essas especies e viabilizando dados para futuras estrategias de conservacao. PATTERNS AND TRENDS OF SCIENTIFIC PRODUCTION ON ANURANS OF THE MIDWESTERN REGION OF BRAZIL. The Midwest region Brazilian stands out for the expansion of the agricultural frontier and important technological advances as agents of growth of modern agriculture, generating concern in terms of biodiversity conservation. Allied to this, it should be noted that amphibians are the most threatened vertebrate group in the world, suffering a sharp decline, being habitat loss and fragmentation considered the main causes of extinction. In this scenario, analyze trends in scientific production is a useful method to maximize conservation efforts. In this study, a scienciometric analysis was performed on frogs in the Midwest region of Brazil to determine gaps and trends in scientific production. The data showed significant increase in the number of publications in the last 18 years. However, the results indicated the preference of researchers for certain areas of knowledge, highlighting a larger number of research on natural history, taxonomy and inventories, in that order, showing a pattern of incompleteness in the production of knowledge for this taxonomic group. We stress the need for allocations of research efforts in different fields of knowledge, mainly in population dynamics and morphology, enlarging the scientific knowledge about these species and providing data for future conservation strategies.

Objective: to describe the experiences of pregnant women at advanced maternal age assisted in a private hospital. Methods: a qualitative study, carried out with 17 women, by means of semi-structured interviews via telephone. The data was submitted to Thematic Content Analysis. Results: the participants were between 35 and 40 years old. Two categories emerged: Experiencing pregnancy as a couple and family: the preparation of the couple for pregnancy and childbirth (Pregnancy after 35 years old as an element of potentiality; Change in the family routine for the baby’s arrival) and Experiencing pregnancy and its changes: perceiving pregnancy as a healthy and calm experience (Change in emotional patterns related to the pregnancy process). Conclusion: experiencing pregnancy late in life was not a concern for women. Maturity and favorable socioeconomic conditions may have a protective influence on the course of healthy pregnancies in women attending the private health service. Objetivo: descrever as experiências de gestantes em idade materna avançada atendidas em hospital privado. Métodos: estudo qualitativo, realizado com 17 mulheres, por meio de entrevistas semiestruturadas via telefone. Os dados foram submetidos à Análise de Conteúdo Temática. Resultados: as participantes tinham idades entre 35 e 40 anos. Emergiram duas categorias: Experienciando a gestação como casal e família: o preparo do casal para a gestação e o parto (Gestação a partir dos 35 anos como elemento de potencialidade; Mudança na rotina da família para a chegada do bebê) e Vivenciando a gestação e suas alterações: percebendo a gestação como uma vivência saudável e tranquila (Alteração dos padrões emocionais relacionados ao processo gestacional). Conclusão: vivenciar a gestação tardiamente não foi uma preocupação para as mulheres. A maturidade e as condições socioeconômicas favoráveis podem ter influência protetiva para o transcorrer de gestações saudáveis em mulheres atendidas no serviço privado de saúde.

Objective: to describe the experiences of pregnant women at advanced maternal age assisted in a private hospital. Methods: a qualitative study, carried out with 17 women, by means of semi-structured interviews via telephone. The data was submitted to Thematic Content Analysis. Results: the participants were between 35 and 40 years old. Two categories emerged: Experiencing pregnancy as a couple and family: the preparation of the couple for pregnancy and childbirth (Pregnancy after 35 years old as an element of potentiality; Change in the family routine for the baby’s arrival) and Experiencing pregnancy and its changes: perceiving pregnancy as a healthy and calm experience (Change in emotional patterns related to the pregnancy process). Conclusion: experiencing pregnancy late in life was not a concern for women. Maturity and favorable socioeconomic conditions may have a protective influence on the course of healthy pregnancies in women attending the private health service. Objetivo: descrever as experiências de gestantes em idade materna avançada atendidas em hospital privado. Métodos: estudo qualitativo, realizado com 17 mulheres, por meio de entrevistas semiestruturadas via telefone. Os dados foram submetidos à Análise de Conteúdo Temática. Resultados: as participantes tinham idades entre 35 e 40 anos. Emergiram duas categorias: Experienciando a gestação como casal e família: o preparo do casal para a gestação e o parto (Gestação a partir dos 35 anos como elemento de potencialidade; Mudança na rotina da família para a chegada do bebê) e Vivenciando a gestação e suas alterações: percebendo a gestação como uma vivência saudável e tranquila (Alteração dos padrões emocionais relacionados ao processo gestacional). Conclusão: vivenciar a gestação tardiamente não foi uma preocupação para as mulheres. A maturidade e as condições socioeconômicas favoráveis podem ter influência protetiva para o transcorrer de gestações saudáveis em mulheres atendidas no serviço privado de saúde.

(-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy. It was observed that (-)-terpinen-4-ol reduced contraction force in an isolated left atrium at millimolar concentrations. Conversely, it induced a positive inotropic effect and extrasystoles at micromolar concentrations, suggesting that (-)-terpinen-4-ol may have arrhythmogenic activity on cardiac tissue. In anaesthetized animals, (-)-terpinen-4-ol also elicited rhythm disturbance, such as supraventricular tachycardia and atrioventricular block. To investigate the cellular mechanism underlying the dual effect of (-)-terpinen-4-ol on heart muscle, experiments were performed on isolated ventricular cardiomyocytes to determine the effect of (-)-terpinen-4-ol on L-type Ca2+ currents, Ca2+ sparks, and Ca2+ transients. The arrhythmogenic activity of (-)-terpinen-4-ol in vitro and in vivo may be explained by its effect on intracellular Ca2+ handling. Taken together, our data suggest that (-)-terpinen-4-ol has cardiac arrhythmogenic activity.

Quercetin is a plant flavonoid with several biological activities. This study aimed to describe quercetin effects on contractile and electrophysiological properties of the cardiac muscle as well as on calcium handling. Quercetin elicited positive inotropism that was significantly reduced by propranolol indicating an involvement of the sympathetic nervous system. In cardiomyocytes, 30 μM quercetin increased ICa,L at 0 mV from -0.95 ± 0.01 A/F to -1.21 ± 0.08 A/F. The membrane potential at which 50% of the channels are activated (V0.5 ) shifted towards more negative potentials from -13.06 ± 1.52 mV to -19.26 ± 1.72 mV and did not alter the slope factor. Furthermore, quercetin increased [Ca2+ ]i transient by 28% when compared to control. Quercetin accelerated [Ca2+ ]i transient decay time, which could be attributed to SERCA activation. In resting cardiomyocytes, quercetin did not change amplitude or frequency of Ca2+ sparks. In isolated heart, quercetin increased heart rate and decreased PRi, QTc and duration of the QRS complex. Thus, we showed that quercetin activates β-adrenoceptors, leading to increased L-type Ca2+ current and cell-wide intracellular Ca2+ transient without visible changes in Ca2+ sparks.

Objectives The aim of this study was to investigate the cytotoxic effect of new 1,4-naphthoquinone- 1,2,3-triazoles, named C2 to C8 triazole derivatives, towards human cancer cell lines. Methods The effect on cell viability was assessed by MTT and propidium iodide assays. The cytotoxic effect of C2 and C3 in K562 and HL-60 cells were analyzed by flow cytometry, DNA fragmentation and reactive oxygen species (ROS) production. Western blot and q-PCR procedures were also performed. Key findings C2 and C3 inhibited both K562 and HL-60 cells growth in a concentration-dependent manner. C2 presented the highest cytotoxic activity with an IC50 of approximately 14 μm and 41 μm for HL-60 and K562 cells, respectively, while being less toxic to normal peripheral blood monocyte cells. Both derivatives induced cellular changes in HL-60 cells, characteristic of apoptosis, such as mitochondrial membrane depolarization, phosphatidylserine externalization, increasing sub-G1 phase, DNA fragmentation, downregulating Bcl-2 protein and upregulating Bax protein. In K562 cells, C2 and C3 induced S-phase arrest of cell cycle, which was associated with upregulation of p21. The effect of these derivatives in HL-60 cells can be related to the ROS intracellular level. Conclusion Taken together our results showed that C2 and C3 triazole derivatives presented the best potential for drug design.

Background Chagas' disease is one of the leading causes of heart failure in Latin American countries. Despite its great social impact, there is no direct evidence in the literature explaining the development of heart failure in Chagas' disease. Therefore, the main objective of the study was to investigate the development of the Chagas' disease towards its chronic phase and correlate with modifications in the cellular electrophysiological characteristics of the infected heart. Methods and results Using a murine model of Chagas' disease, we confirmed and extended previous findings of altered electrocardiogram and echocardiogram in this cardiomyopathy. The observed changes in the electrocardiogram were correlated with the prolonged action potential and reduced transient outward potassium current density. Reduced heart function was associated with remodeling of intracellular calcium handling, altered extracellular matrix content, and to a set of proteins involved in the control of cellular contractility in ventricular myocytes. Furthermore, disruption of calcium homeostasis was partially due to activation of the PI3Kinase/nitric oxide signaling pathway. Finally, we propose a causal link between the inflammatory mediators and heart remodeling during chagasic cardiomyopathy. Conclusion Altogether our results demonstrate that heart failure in Chagas' disease may occur due to electrical and mechanical remodeling of cardiac myocytes, and suggest that AKT/PI3K/NO axis could be an important pharmacological target to improve the disease outcome.

High serum levels of aldosterone have been linked to the development of cardiac disease. In contrast, angiotensin (Ang)-(1-7) was extensively shown to possess cardioprotective effects, including the attenuation of cardiac dysfunction induced by excessive mineralocorticoid activation in vivo, suggesting possible interactions between these 2 molecules. Here, we investigated whether there is cross-talk between aldosterone and Ang-(1-7) and its functional consequences for calcium (Ca 2+ ) signaling in ventricular myocytes. Short-term effects of aldosterone on Ca 2+ transient were assessed in Fluo-4/AM-loaded myocytes. Confocal images showed that Ang-(1-7) had no effect on Ca 2+ transient parameters, whereas aldosterone increased the magnitude of the Ca 2+ transient. Quite unexpectedly, addition of Ang-(1-7) to aldosterone-treated myocytes further enhanced the amplitude of the Ca 2+ transient suggesting a synergistic effect of these molecules. Aldosterone action on Ca 2+ transient amplitude was mediated by protein kinase A, and was related to an increase in Ca 2+ current ( I Ca ) density. Both changes were not altered by Ang-(1-7). When cardiomyocytes were exposed to aldosterone, increased Ca 2+ spark rate was measured. Ang-(1-7) prevented this change. In addition, a NO synthase inhibitor restored the effect of aldosterone on Ca 2+ spark rate in Ang-(1-7)-treated myocytes and attenuated the synergistic effect of these 2 molecules on Ca 2+ transient. These results indicate that NO plays an important role in this cross-talk. Our results bring new perspectives in the understanding of how 2 prominent molecules with supposedly antagonist cardiac actions cross-talk to synergistically amplify Ca 2+ signals in cardiomyocytes.

(-)-Terpinen-4-ol is a naturally occurring plant monoterpene and has been shown to have a plethora of biological activities. The objective of this study was to investigate the effects of (-)-terpinen-4-ol on the rat heart, a key player in the control and maintenance of arterial blood pressure. The effects of (-)-terpinen-4-ol on the rat heart were investigated using isolated left atrium isometric force measurements, in vivo electrocardiogram (ECG) recordings, patch clamp technique, and confocal microscopy. It was observed that (-)-terpinen-4-ol reduced contraction force in an isolated left atrium at millimolar concentrations. Conversely, it induced a positive inotropic effect and extrasystoles at micromolar concentrations, suggesting that (-)-terpinen-4-ol may have arrhythmogenic activity on cardiac tissue. In anaesthetized animals, (-)-terpinen-4-ol also elicited rhythm disturbance, such as supraventricular tachycardia and atrioventricular block. To investigate the cellular mechanism underlying the dual effect of (-)-terpinen-4-ol on heart muscle, experiments were performed on isolated ventricular cardiomyocytes to determine the effect of (-)-terpinen-4-ol on L-type Ca

Background Hadruroides lunatus is the most abundant scorpion species in the Peruvian central coast, where most of the accidents involving humans are registered. In spite of its prevalence, there are only very few studies on H. lunatus envenomation. The aim of the present study was to analyze the cardiorespiratory alterations caused by H. lunatus envenomation in rodents. Methods Wistar rats injected with H. lunatus scorpion venom were submitted to electrocardiography. After euthanasia, rat lungs were collected and histopathologically analyzed. Mouse cardiomyocytes were used to perform immunofluorescence and calcium transient assays. Data were analyzed by ANOVA or Student’s t-test. The significance level was set at p< 0.05. Results It was observed that H. lunatus venom increased heart rate and caused arrhythmia, thereby impairing the heart functioning. Lungs of envenomed animals showed significant alterations, such as diffuse hemorrhage. In addition, immunofluorescence showed that H. lunatus venom was capable of binding to cardiomyocytes. Furthermore, mouse ventricular cardiomyocytes incubated with H. lunatus venom showed a significant decrease in calcium transient, confirming that H. lunatus venom exerts a toxic effect on heart. Conclusion Our results showed that H. lunatus venom is capable of inducing cardiorespiratory alterations, a typical systemic effect of scorpionism, stressing the importance of medical monitoring in envenomation cases.

The present study aimed to investigate the inotropic effects of R(+)-pulegone, a monoterpene found in plant species belonging to the genus Mentha, on the mammalian heart. In electrically stimulated guinea pig atria, R(+)-pulegone reduced the contractile force (~ 83%) and decreased the contraction time measured at 50% of the maximum force amplitude (CT50) from 45.8 ± 6.2 ms to 36.9 ± 6.2 ms, suggesting that R(+)-pulegone may have an effect on Ca2+ homeostasis. Nifedipine (40 μM), taken as a positive control, showed a very similar profile. To explore the hypothesis that R(+)-pulegone is somehow affecting Ca2+ handling, we determined concentration–response curves for both CaCl2 and BAY K8644. R(+)-pulegone shifted these curves rightward. Using isolated mouse ventricular cardiomyocytes, we measured whole-cell L-type Ca2+ current and observed an ICa,L peak reduction of 13.7 ± 2.5% and 40.2 ± 2.9% after a 3-min perfusion with 0.11 and 1.1 mM of R(+)-pulegone, respectively. In addition, the intracellular Ca2+ transient was decreased (72.9%) by 3.2 mM R(+)-pulegone, with no significant changes in [Ca2+]i transient decay kinetics. Moreover, R(+)-pulegone at 1.1 mM prolonged the action potential duration at 10, 50, and 90% of repolarisation. The lengthening of the action potential duration may be attributed to the substantial blockade of the outward K+ currents caused by 1.1 mM of R(+)-pulegone (90.5% at 60 mV). These findings suggest that R(+)-pulegone exerts its negative inotropic effect on mammalian heart mainly by decreasing the L-type Ca2+ current and the global intracellular Ca2+ transient.

[ES] Este trabajo expone el análisis fractal en pintura rupestre por medio de la dimensión D. Los fractales es una herramienta en la aplicación consoftware y fotografía digital para el reconocimiento de materias primas, el estudio de su forma, su degradación, partes específicas de la misma, y favorecer la reconstrucción virtual.Los análisis se centraron en diversos conjuntos pictóricos de la región “Valle del Mezquital, Hidalgo, México; región donde se concentran más de 100 conjuntos rupestres agrupados en barrancas, siendo comparados 10 abrigos con 74 figuras para localizar las distintas tradiciones pictóricas. La dimensión fractal describe la dimensión de los objetos representados, no sólo de acuerdo a su espacio donde se sitúa la figura, sino la posibilidad de ser un número fraccionario en el cual se pueden observar todas las superficies posibles., [EN] This study exposed analysis fractal by the dimension D in the rock art. The Fractals is a new tool in the software application and digital photographyfor the recognition of raw materials, the study of its form, degradation, specific parts of paint, and providing new data the virtual reconstruction.The analyzes focus on various pictorial sets of the region Mezquital Valley, Hidalgo, Mexico; region where are concentrated more than 100 caves, comparing 74 images to analyze the various pictorial traditions.The structure fractal describes the dimension of the represented objects, not only according to its space where the figure is placed, but the possibility of being a fraction in which all the surfaces can be observed (rock, paint).

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-07T19:03:09Z No. of bitstreams: 1 Aline Lara Fernandes Alonso.pdf: 2165402 bytes, checksum: 7426e9fb75a011a406974964cf9dec4b (MD5) Made available in DSpace on 2021-01-07T19:03:09Z (GMT). No. of bitstreams: 1 Aline Lara Fernandes Alonso.pdf: 2165402 bytes, checksum: 7426e9fb75a011a406974964cf9dec4b (MD5) Previous issue date: 2014-01-21 In this study samples of sediment of three beaches of Guanabara Bay, Rio de Janeiro, (São Bento beach and Bica beach, in Ilha do Governador and São Francisco beach, in Niterói) were analyzed to investigate the contamination with microplastics (plastic fragments ≤ 5 mm). Samples of sediment were examined by naked eye to sort items of plastic debris from other materials. After separation plastic items were weighted. Non visible plastic debris were separated from sediments by density difference applying a concentrated saline NaCℓ solution. Plastic fragments picked up from supernatant were characterized by optical microscopy to analyze morphology and classified in size fractions. From sediments of Bica beach were collected 173 plastic fragments and 73% of them were microplastic. In São Bento beach were collected 81 fragments and in São Francisco beach were collected 73 fragments, from which 70% and 86%, respectively, were microplastic. The three beaches are contaminated with both microplastic and macroplastic. Microplastic fragments were characterized by ATR FT IR. Expanded polystyrene microplastic fragments were found in sediments of the three beaches. Polyethylene microplastic fragments were found in sediments of Bica and São Bento beaches and polypropylene microplastic fragments were found in sediments of São Bento and São Francisco beaches. Littering, illegal-dumping and industrial activities are possible sources of microplastic contamination of Guanabara Bay Neste trabalho foram analisados sedimentos marinhos de três praias da Baía de Guanabara (praia de São Bento e praia da Bica, na Ilha do Governador, e praia de São Francisco, em Niterói), Rio de Janeiro, para avaliar a presença de microplásticos (fragmentos plásticos com tamanho ≤ 5 mm) nestes ambientes. Os detritos plásticos visíveis (macroplástico) foram separados dos sedimentos manualmente e pesados. Os detritos plásticos não visíveis foram separados por densidade com solução saturada de cloreto de sódio. Os fragmentos plásticos obtidos com a separação por densidade foram caracterizados por microscopia óptica para avaliar forma e superfície, e foram classificados e quantificados em função de seu tamanho. Os fragmentos microplásticos foram separados e caracterizados por espectrometria de absorção na região do infravermelho por reflexão atenuada (ATR FT IR). Os espectros obtidos foram comparados com espectros padrão de polímeros. As três praias se apresentam contaminadas com lixo macroplástico e com lixo microplástico. Na praia da Bica, foram coletados 173 fragmentos, dos quais 73% são microplásticos. Na praia de São Bento foram 81 fragmentos e na praia de São Francisco foram 73 fragmentos, dos quais 70% e 86%, respectivamente, são microplásticos. Nas três praias foram encontrados fragmentos microplásticos de poliestireno expandido. Nas praias da Bica e de São Bento foram encontrados fragmentos de polietileno; nas praias de São Bento e São Francisco foram encontrados fragmentos microplásticos de polipropileno. O descarte irregular de lixo e atividades industriais e comerciais no entorno da baía podem ser apontados como possíveis fontes contaminantes

Cholinergic control of the heart is exerted by two distinct branches; the autonomic component represented by the parasympathetic nervous system, and the recently described non-neuronal cardiomyocyte cholinergic machinery. Previous evidence has shown that reduced cholinergic function leads to deleterious effects on the myocardium. Yet, whether conditions of increased cholinergic signaling can offset the pathological remodeling induced by sympathetic hyperactivity, and its consequences for these two cholinergic axes are unknown. Here, we investigated two models of sympathetic hyperactivity: i) the chronic beta-adrenergic receptor stimulation evoked by isoproterenol (ISO), and ii) the alpha(2A)/alpha(2C)-drenergic receptor knockout (KO) mice that lack pre-synaptic adrenergic receptors. In both models, cholinergic signaling was increased by administration of the cholinesterase inhibitor, pyridostigmine. First, we observed that isoproterenol produces an autonomic imbalance characterized by increased sympathetic and reduced parasympathetic tone. Under this condition transcripts for cholinergic proteins were upregulated in ventricular myocytes, indicating that non-neuronal cholinergic machinery is activated during adrenergic overdrive. Pyridostigmine treatment prevented the effects of ISO on autonomic function and on the ventricular cholinergic machinery, and inhibited cardiac remodeling. alpha(2A)/alpha(2C)-KO mice presented reduced ventricular contraction when compared to wild-type mice, and this dysfunction was also reversed by cholinesterase inhibition. Thus, the cardiac parasympathetic system and non-neuronal cardiomyocyte cholinergic machinery are modulated in opposite directions under conditions of increased sympathetic drive or ACh availability. Moreover, our data support the idea that pyridostigmine by restoring ACh availability is beneficial in heart disease.

Recent work has provided compelling evidence that increased levels of acetylcholine (ACh) can be protective in heart failure, whereas reduced levels of ACh secretion can cause heart malfunction. Previous data show that cardiomyocytes themselves can actively secrete ACh, raising the question of whether this cardiomyocyte derived ACh may contribute to the protective effects of ACh in the heart. To address the functionality of this non-neuronal ACh machinery, we used cholinesterase inhibitors and a siRNA targeted to AChE (acetylcholinesterase) as a way to increase the availability of ACh secreted by cardiac cells. By using nitric oxide (NO) formation as a biological sensor for released ACh, we showed that cholinesterase inhibition increased NO levels in freshly isolated ventricular myocytes and that this effect was prevented by atropine, a muscarinic receptor antagonist, and by inhibition of ACh synthesis or vesicular storage. Functionally, cholinesterase inhibition prevented the hypertrophic effect as well as molecular changes and calcium transient alterations induced by adrenergic overstimulation in cardiomyocytes. Moreover, inhibition of ACh storage or atropine blunted the anti-hypertrophic action of cholinesterase inhibition. Altogether, our results show that cardiomyocytes possess functional cholinergic machinery that offsets deleterious effects of hyperadrenergic stimulation. In addition, we show that adrenergic stimulation upregulates expression levels of cholinergic components. We propose that this cardiomyocyte cholinergic signaling could amplify the protective effects of the parasympathetic nervous system in the heart and may counter-act or partially neutralize hypertrophic adrenergic effects.

Autonomic dysfunction is observed in many cardiovascular diseases and contributes to cardiac remodeling and heart disease. We previously reported that a decrease in the expression levels of the vesicular acetylcholine transporter (VAChT) in genetically-modified homozygous mice (VAChT KD(HOM)) leads to decreased cholinergic tone, autonomic imbalance and a phenotype resembling cardiac dysfunction. In order to further understand the molecular changes resulting from chronic long-term decrease in parasympathetic tone, we undertook a transcriptome-based, microarray-driven approach to analyze gene expression changes in ventricular tissue from VAChT KD(HOM) mice. We demonstrate that a decrease in cholinergic tone is associated with alterations in gene expression in mutant hearts, which might contribute to increased ROS levels observed in these cardiomyocytes. In contrast, in another model of cardiac remodeling and autonomic imbalance, induced through chronic isoproterenol treatment to increase sympathetic drive, these genes did not appear to be altered in a pattern similar to that observed in VAChT KD(HOM) hearts. These data suggest the importance of maintaining a fine balance between the two branches of the autonomic nervous system and the significance of absolute levels of cholinergic tone in proper cardiac function.

The present study aimed to investigate the inotropic effects of R(+)-pulegone, a monoterpene found in plant species belonging to the genus Mentha, on the mammalian heart. In electrically stimulated guinea pig atria, R(+)-pulegone reduced the contractile force (~83%) and decreased the contraction time measured at 50% of the maximum force amplitude (CT(50)) from 45.8 ± 6.2 ms to 36.9 ± 6.2 ms, suggesting that R(+)-pulegone may have an effect on Ca(2+) homeostasis. Nifedipine (40 μM), taken as a positive control, showed a very similar profile. To explore the hypothesis that R(+)-pulegone is somehow affecting Ca(2+) handling, we determined concentration-response curves for both CaCl(2) and BAY K8644. R(+)-pulegone shifted these curves rightward. Using isolated mouse ventricular cardiomyocytes, we measured whole-cell L-type Ca(2+) current and observed an I(Ca,L) peak reduction of 13.7 ± 2.5% and 40.2 ± 2.9% after a 3-min perfusion with 0.11 and 1.1mM of R(+)-pulegone, respectively. In addition, the intracellular Ca(2+) transient was decreased (72.9%) by 3.2mM R(+)-pulegone, with no significant changes in [Ca(2+)](i) transient decay kinetics. Moreover, R(+)-pulegone at 1.1mM prolonged the action potential duration at 10, 50, and 90% of repolarisation. The lengthening of the action potential duration may be attributed to the substantial blockade of the outward K(+) currents caused by 1.1mM of R(+)-pulegone (90.5% at 60 mV). These findings suggest that R(+)-pulegone exerts its negative inotropic effect on mammalian heart mainly by decreasing the L-type Ca(2+) current and the global intracellular Ca(2+) transient.

2010, 【要旨】

Overwhelming evidence supports the importance of the sympathetic nervous system in heart failure. In contrast, much less is known about the role of failing cholinergic neurotransmission in cardiac disease. By using a unique genetically modified mouse line with reduced expression of the vesicular acetylcholine transporter (VAChT) and consequently decreased release of acetylcholine, we investigated the consequences of altered cholinergic tone for cardiac function. M-mode echocardiography, hemodynamic experiments, analysis of isolated perfused hearts, and measurements of cardiomyocyte contraction indicated that VAChT mutant mice have decreased left ventricle function associated with altered calcium handling. Gene expression was analyzed by quantitative reverse transcriptase PCR and Western blotting, and the results indicated that VAChT mutant mice have profound cardiac remodeling and reactivation of the fetal gene program. This phenotype was attributable to reduced cholinergic tone, since administration of the cholinesterase inhibitor pyridostigmine for 2 weeks reversed the cardiac phenotype in mutant mice. Our findings provide direct evidence that decreased cholinergic neurotransmission and underlying autonomic imbalance cause plastic alterations that contribute to heart dysfunction.

The renin-angiotensin (Ang) system plays a pivotal role in the pathogenesis of cardiovascular disease, with Ang II being the major effector of this system. Multiple lines of evidence have shown that Ang-(1-7) exerts cardioprotective effects in the heart by counterregulating Ang II actions. The questions that remain are how and where Ang-(1-7) exerts its effects. By using a combination of molecular biology, confocal microscopy, and a transgenic rat model with increased levels of circulating Ang-(1-7) (TGR[A1-7]3292), we evaluated the signaling pathways involved in Ang-(1-7) cardioprotection against Ang II–induced pathological remodeling in ventricular cardiomyocytes. Rats were infused with Ang II for 2 weeks. We found that ventricular myocytes from TGR(A1-7)3292 rats are protected from Ang II pathological remodeling characterized by Ca 2+ signaling dysfunction, hypertrophic fetal gene expression, glycogen synthase kinase 3β inactivation, and nuclear factor of activated T-cells nuclear accumulation. Moreover, cardiomyocytes from TGR(A1-7)3292 rats infused with Ang II presented increased expression levels of neuronal NO synthase. To provide a signaling pathway involved in the beneficial effects of Ang-(1-7), we treated neonatal cardiomyocytes with Ang-(1-7) and Ang II for 36 hours. Treatment of cardiomyocytes with Ang-(1-7) prevented Ang II–induced hypertrophy by modulating calcineurin/nuclear factor of activated T-cell signaling cascade. Importantly, antihypertrophic effects of Ang-(1-7) on Ang II–treated cardiomyocytes were prevented by N G -nitro- l -arginine methyl ester and 1H-1,2,4oxadiazolo4,2-aquinoxalin-1-one, suggesting that these effects are mediated by NO/cGMP. Taken together, these data reveal a key role for NO/cGMP as a mediator of Ang-(1-7) beneficial effects in cardiac cells.