BackgroundSuccinate is an intermediate of the citric acid cycle as well as an extracellular circulating molecule, whose receptor, G protein-coupled receptor-91 (GPR91), was recently identified and characterized in several tissues, including heart. Because some pathological conditions such as ischemia increase succinate blood levels, we investigated the role of this metabolite during a heart ischemic event, using human and rodent models.ResultsWe found that succinate causes cardiac hypertrophy in a GPR91 dependent manner. GPR91 activation triggers the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), the expression of calcium/calmodulin dependent protein kinase IIδ (CaMKIIδ) and the translocation of histone deacetylase 5 (HDAC5) into the cytoplasm, which are hypertrophic-signaling events. Furthermore, we found that serum levels of succinate are increased in patients with cardiac hypertrophy associated with acute and chronic ischemic diseases.ConclusionsThese results show for the first time that succinate plays an important role in cardiomyocyte hypertrophy through GPR91 activation, and extend our understanding of how ischemia can induce hypertrophic cardiomyopathy.Electronic supplementary materialThe online version of this article (doi:10.1186/s12964-014-0078-2) contains supplementary material, which is available to authorized users.

In this study we evaluated the cardiac effects of a pharmaceutical formulation developed by including angiotensin (Ang)-(1-7) in hydroxypropyl β-cyclodextrin (HPβCD), in normal, infarcted, and isoproterenol-treated rats. Myocardial infarction was produced by left coronary artery occlusion. Isoproterenol (2 mg/kg, IP) was administered daily for 7 days. Oral administration of HPβCD/Ang-(1-7) started immediately before infarction or associated with the first dose of isoproterenol. After 7 days of treatment, the rats were euthanized, and the Langendorff technique was used to analyze cardiac function. In addition, heart function was chronically (15, 30, 50 days) analyzed by echocardiography. Cardiac sections were stained with hematoxylin/eosin and Masson trichrome to evaluate cardiac hypertrophy and damage, respectively. Pharmacokinetic studies showed that oral HPβCD/Ang-(1-7) administration significantly increased Ang-(1-7) on plasma whereas with the free peptide it was without effect. Oral administration of HPβCD/Ang-(1-7) (30 μg/kg) significantly reduced the deleterious effects induced by myocardial infarction on systolic and diastolic tension, ±dT/dt, perfusion pressure, and heart rate. Strikingly, a 50% reduction of the infarcted area was observed in HPβCD/Ang-(1-7)-treated rats. Furthermore, HPβCD/Ang-(1-7) attenuated the heart function impairment and cardiac remodeling induced by isoproterenol. In infarcted rats chronically treated with HPβCD/Ang-(1-7), the reduction of ejection fraction and fractional shorting and the increase in systolic and diastolic left ventricular volumes observed in infarcted rats were attenuated. Altogether, these findings further confirm the cardioprotective effects of Ang-(1-7). More importantly, our data indicate that the HPβCD/Ang-(1-7) is a feasible formulation for oral administration of Ang-(1-7), which can be used as a cardioprotective drug.

We evaluated the hypothesis that activation of endogenous angiotensin-converting enzyme (ACE) 2 would improve cardiac dysfunction induced by diabetes. Ten days after diabetes induction (streptozotocin, 50mg/kg, i.v.), male Wistar rats were treated with the ACE2 activator 1-[[2-(dimethylamino)ethyl]amino]-4-(hydroxymethyl)-7-[[(4-methylphenyl)sulfonyl]oxy]-9H-xanthen-9-one (XNT, 1mg/kg/day, gavage) or saline (control) for 30 days. Echocardiography was performed to analyze the cardiac function and kinetic fluorogenic assays were used to determine cardiac ACE and ACE2 activities. Cardiac ACE2, ACE, Mas receptor, AT1 receptor, AT2 receptor and collagen type I and III mRNA and ACE2, ACE, Mas, AT1 receptor, AT2 receptor, ERK1/2, Akt, AMPK-α and AMPK-β1 protein were measured by qRT-PCR and western blotting techniques, respectively. Histological sections of hearts were analyzed to evaluate the presence of hypertrophy and fibrosis. Diabetic animals presented hyperglycemia and diastolic dysfunction along with cardiac hypertrophy and fibrosis. XNT treatment prevented further increase in glycemia and improved the cardiac function, as well as the hypertrophy and fibrosis. These effects were associated with increases in cardiac ACE2/ACE ratios (activity: ~26%; mRNA: ~113%; and protein: ~188%) and with a decrease in AT1 receptor expression. Additionally, XNT inhibited ERK1/2 phosphorylation and prevented changes in AMPK-α and AMPK-β1 expression. XNT treatment did not induce any significant change in AT2 receptor and Akt expression. These results indicate that activation of intrinsic cardiac ACE2 by oral XNT treatment protects the heart against diabetes-induced dysfunction through mechanisms involving ACE, ACE2, ERK1/2, AMPK-α and AMPK-β1 modulation.

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 α2A/α2C-adrenergic 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. α2A/α2C-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.

In this study was evaluated the chronic cardiac effects of a formulation developed by including angiotensin(Ang)-(1–7) in hydroxypropyl β-cyclodextrin (HPβCD), in infarcted rats. Myocardial infarction (MI) was induced by left coronary artery occlusion. HPβCD/Ang-(1–7) was administered for 60 days (76 μg/Kg/once a day/gavage) starting immediately before infarction. Echocardiography was utilized to evaluate usual cardiac parameters, and radial strain method was used to analyze the velocity and displacement of myocardial fibers at initial time and 15, 30, and 50 days after surgery. Real-time PCR was utilized to evaluate the fibrotic signaling involved in the remodeling process. Once-a-day oral HPβCD/Ang-(1–7) administration improved the cardiac function and reduced the deleterious effects induced by MI on TGF-β and collagen type I expression, as well as on the velocity and displacement of myocardial fibers. These findings confirm cardioprotective effects of Ang-(1–7) and indicate HPβCD/Ang-(1–7) as a feasible formulation for long-term oral administration of this heptapeptide.

Cardiovascular diseases are the number one cause of death globally and are projected to remain the single leading cause of death. Treatment options abounds, although efficacy is limited. Recent studies attribute discrete and ephemeral benefits to adult stem cell therapies, indicating the urge to improve stem cell based–therapy. In this study, we show that priming mesenchymal stem cells (MSC) towards cardiomyogenic lineage enhances their beneficial effects in vivo as treatment option for acute phase myocardial infarction. MSC were primed using cardiomyogenic media for 4 days, after which peak expression of key cardiomyogenic genes are reached and protein expression of Cx-43 and sarcomeric α-actinin are observed. MSC and primed MSC (pMSC) were characterized in vitro and used to treat infarcted rats immediately after left anterior descending (LAD) occlusion. Echocardiography analysis indicated that MSC-treated myocardium presented discrete improvement in function, but it also showed that pMSC treatment lead to superior beneficial results, compared with undifferentiated MSC. Seven days after cell injection, MSC and pMSC could still be detected in the myocardium. Connexin-43 expression was quantified through immunoblotting, and was superior in pMSC, indicating that this could be a possible explanation for the superior performance of pMSC therapy.

Comunicação [Communication] Dopplerfluxometria das artérias renais: valores normais das velocidades sistólica e diastólica e do índice resistivo nas artérias renais principais [Renal arteries Dopplerfluxometry: normal A prevalência de doenças renais é alta na clínica de pequenos animais, afetando aproximadamente 1% dos cães atendidos (MacDougall et al., 1986). Em animais idosos, acima de 15 anos de idade, esse percentual pode atingir 10% (Polzin et al., 1992). Além da idade avançada, fatores como alterações congênitas, alimentação inadequada, utilização de drogas nefrotóxicas, intoxicações e doenças infecciosas predispõem caninos e felinos a lesões do parênquima renal. Na medicina veterinária, diversos estudos estão sendo realizados com o intuito de se descobrir métodos de avaliação e detecção precoce de doenças renais. Alguns métodos de avaliação da função renal, apesar de eficazes, são complexos e invasivos, o que limita o seu uso na rotina. Segundo Miyamoto et al. (1997) (2002), o uso do Doppler para avaliação dos rins de animais tem origem em estudos realizados em humanos. Nestes, a técnica tem demonstrado ser útil para fornecer informações adicionais, em pacientes portadores de insuficiência renal aguda, na obstrução do trato urinário, nas neoplasias renais e em pacientes pós-transplante renal. Estudos em animais têm sido realizados para mostrar as possibilidades da técnica para a avaliação de várias doenças renais. Os trabalhos de Morrow et al. (1996), Rivers et al. (1996) e Rivers et al. (1997 demonstraram a utilidade da técnica em cães portadores de nefrites, insuficiência renal aguda e glomerulopatias.A medida das velocidades dos fluxos sistólico e diastólico das artérias renais permite o cálculo do índice resistivo (IR), valor adimensional criado para estimar a resistência de leitos vasculares regionais (Rivers et al., 1997).Para a realização deste estudo, foram utilizados 20 cães, sem raça definida, 10 machos e 10 fêmeas, adultos, com peso médio de 11,53±4,81 quilos. Todos os animais foram considerados normais, tendo sido realizados exames clínicos e laboratoriais de hemograma, dosagem sérica de

Doxorubicin (Dox) is one of the most effective chemotherapeutic agents; however, it causes dose-dependent cardiotoxicity. Evaluation of left ventricular function relies on measurements based on M-mode echocardiography. A new technique based on quantification of myocardial motion and deformation, strain echocardiography, has been showed promising profile for early detection of cardiac dysfunction. Different therapy strategies, such as flavonoid plant extracts and stem cells, have been investigated to improve heart function in toxic cardiomyopathy. This work aimed to assess early cardiac function improvement after treatments with either flavonoid extract from Camellia sinensis or mesenchymal stem cells in Dox cardiotoxicity using strain echocardiography. Twenty Wistar rats were randomly assigned to four groups. They received water (control, Dox, Dox + stem cells) or 100 mg/kg C. sinensis extract (Dox + C. sinensis) via gavage, daily, for four weeks. Animals also received saline (control) or 5 mg/kg doxorubicin (Dox, Dox + C. sinensis, Dox + stem cells) via intraperitoneal injection, weekly, for four weeks. Stem cells were injected (3 × 106 cells) through tail vein prior the beginning of the experiment (Dox + stem cells). Animals were evaluated by hematological, electrocardiography, echocardiography, and histopathological examinations. Dox cardiotoxicity was only diagnosed with strain echocardiography, detecting a decrease in ventricular function. C. sinensis extract did not prevent ventricular dysfunction induced by Dox. However, strain echocardiography examination revealed that Dox cardiotoxicity was significantly suppressed in rats treated with stem cells. In conclusion, strain echocardiography was able to detect precocity signs of heart failure and stem cell therapy showed cardioprotection effect against Dox cardiotoxicity.