RESUMO
Background: Peptidylglycine α-amidating monooxygenase (PAM) is an enzyme involved in the maturation of regulatory peptides. Here we examined PAM activity and adrenomedullin (bio-ADM) concentrations in patients with hepatic cirrhosis and determined net changes across the liver, kidneys and leg. Materials & methods: A total of 48 patients with hepatic cirrhosis and 16 control subjects were included. All patients and controls underwent an invasive procedure with blood collected across organs. Results: PAM activity was increased in cirrhotic patients but without a net change across the liver, leg or kidney. In contrast, bio-ADM concentrations were associated with severity of disease and found to be higher in venous blood from the liver. Conclusion: Increased PAM activity in patients with hepatic cirrhosis may reflect other organs involved in cirrhotic disease.
Severe liver disease is a life-threatening condition that affects people all over the world. To improve doctors' ability to diagnose the disease and to follow the disease as it progresses, there is a need for new tools. Biomarkers are often used as such tools for measuring the presence and severity of a disease. In this study, we examined two potential biomarkers in blood from patients with severe liver disease: peptidylglycine α-amidating monooxygenase (PAM) activity and bioactive adrenomedullin (bio-ADM). We examined whether these biomarkers are present in blood and in amounts associated with disease severity. We also tested if the diseased liver releases the biomarkers. We found that bio-ADM is increased in blood from patients with severe liver disease and that the liver itself releases bio-ADM to the bloodstream. For PAM activity, we also detected increased activity in blood associated with disease severity. In contrast, however, this biomarker was not shown to be released by the liver. Taken together, the two biomarkers may help to improve severe liver disease diagnosis and maybe allow for biochemical follow-up as the disease progresses.
Assuntos
Adrenomedulina , Oxigenases de Função Mista , Humanos , Complexos Multienzimáticos , Cirrose HepáticaRESUMO
The purpose of this study was to identify and validate new putative lead drug targets in drug-resistant mesial temporal lobe epilepsy (mTLE) starting from differentially expressed genes (DEGs) previously identified in mTLE in humans by transcriptome analysis. We identified consensus DEGs among two independent mTLE transcriptome datasets and assigned them status as "lead target" if they (1) were involved in neuronal excitability, (2) were new in mTLE, and (3) were druggable. For this, we created a consensus DEG network in STRING and annotated it with information from the DISEASES database and the Target Central Resource Database (TCRD). Next, we attempted to validate lead targets using qPCR, immunohistochemistry, and Western blot on hippocampal and temporal lobe neocortical tissue from mTLE patients and non-epilepsy controls, respectively. Here we created a robust, unbiased list of 113 consensus DEGs starting from two lists of 3040 and 5523 mTLE significant DEGs, respectively, and identified five lead targets. Next, we showed that CACNB3, a voltage-gated Ca2+ channel subunit, was significantly regulated in mTLE at both mRNA and protein level. Considering the key role of Ca2+ currents in regulating neuronal excitability, this suggested a role for CACNB3 in seizure generation. This is the first time changes in CACNB3 expression have been associated with drug-resistant epilepsy in humans, and since efficient therapeutic strategies for the treatment of drug-resistant mTLE are lacking, our finding might represent a step toward designing such new treatment strategies.
Assuntos
Epilepsia Resistente a Medicamentos , Epilepsia do Lobo Temporal , Humanos , Epilepsia do Lobo Temporal/tratamento farmacológico , Epilepsia do Lobo Temporal/genética , Epilepsia do Lobo Temporal/complicações , Lobo Temporal/metabolismo , Convulsões/metabolismo , Hipocampo/metabolismo , Epilepsia Resistente a Medicamentos/genética , Epilepsia Resistente a Medicamentos/metabolismoRESUMO
BACKGROUND: According to patterns of inheritance and incomplete penetrance, fewer than half of relatives to dilated cardiomyopathy probands will develop disease. OBJECTIVES: The purpose of this study was to investigate the prevalence and incidence, and to identify predictors of developing familial dilated cardiomyopathy (FDC) in relatives participating in family screening. METHODS: The study was a retrospective, longitudinal cohort study of families screened and followed from 2006 to 2020 at a regional assembly of clinics for inherited cardiomyopathies. RESULTS: In total, 211 families (563 relatives, 50% women) were included. At baseline, 124 relatives (22%) were diagnosed with FDC. Genetic sequencing identified the etiology in 37% of screened families and classified 101 (18%) relatives as unaffected carriers (n = 43) or noncarriers (ie, not at risk of FDC [n = 58]). The combined clinical and genetic baseline yield was 30%. During follow-up (2,313 person-years, median 5.0 years), 45 developed FDC (incidence rate of 2.0% per person-year; 95% CI: 1.4%-2.8%), increasing the overall yield to 34%. The incidence rate of FDC was high in relatives with baseline abnormalities on electrocardiogram or echocardiography compared with relatives with normal findings (4.7% vs 0.4% per person-year; HR: 12.9; P < 0.001). In total, baseline screening identified 326 (58%) relatives to be at low risk of FDC. CONCLUSIONS: Family screening identified a genetic predisposition to or overt FDC in 1 of 3 relatives at baseline. Genetic and clinical screening was normal in more than half of relatives, and these relatives had a low risk of developing FDC during follow-up. Thus, baseline screening identified a large proportion, in whom follow-up may safely be reduced, allowing focused follow-up of relatives at risk.
Assuntos
Cardiomiopatia Dilatada , Insuficiência Cardíaca , Humanos , Feminino , Masculino , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/epidemiologia , Cardiomiopatia Dilatada/genética , Incidência , Prevalência , Seguimentos , Estudos Retrospectivos , Estudos LongitudinaisRESUMO
Production and release of natriuretic peptides and other vasoactive peptides are tightly regulated in mammalian physiology and involved in cardiovascular homeostasis. As endocrine cells, the cardiac myocytes seem to possess almost all known chemical necessities for translation, post-translational modifications, and complex peptide proteolysis. In several ways, intracellular granules in the cells contain not only peptides destined for secretion but also important granin molecules involved in maintaining a regulated secretory pathway. In this review, we will highlight the biochemical phenotype of the endocrine heart recapitulating that the cardiac myocytes are capable endocrine cells. Understanding the basal biochemistry of the endocrine heart in producing and secreting peptides to circulation could lead to new discoveries concerning known peptide products as well as hitherto unidentified cardiac peptide products. In perspective, studies on natriuretic peptides in the heart have shown that the post-translational phase of gene expression is not only relevant for human physiology but may prove implicated also in the development and, perhaps one day, cure of human cardiovascular disease.
RESUMO
Despite improvements in revascularization after a myocardial infarction, coronary disease remains a major contributor to global mortality. Neutrophil infiltration and activation contributes to tissue damage, via the release of myeloperoxidase (MPO) and formation of the damaging oxidant hypochlorous acid. We hypothesized that elevation of thiocyanate ions (SCN-), a competitive MPO substrate, would modulate tissue damage. Oral dosing of rats with SCN-, before acute ischemia-reperfusion injury (30 min occlusion, 24 h or 4 week recovery), significantly reduced the infarct size as a percentage of the total reperfused area (54% versus 74%), and increased the salvageable area (46% versus 26%) as determined by MRI imaging. No difference was observed in fractional shortening, but supplementation resulted in both left-ventricle end diastolic and left-ventricle end systolic areas returning to control levels, as determined by echocardiography. Supplementation also decreased antibody recognition of HOCl-damaged myocardial proteins. SCN- supplementation did not modulate serum markers of damage/inflammation (ANP, BNP, galectin-3, CRP), but returned metabolomic abnormalities (reductions in histidine, creatine and leucine by 0.83-, 0.84- and 0.89-fold, respectively), determined by NMR, to control levels. These data indicate that elevated levels of the MPO substrate SCN-, which can be readily modulated by dietary means, can protect against acute ischemia-reperfusion injury.
Assuntos
Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Tiocianatos/administração & dosagem , Animais , Débito Cardíaco , Colágeno/análise , Suplementos Nutricionais , Ecocardiografia , Coração/diagnóstico por imagem , Masculino , Metaboloma , Traumatismo por Reperfusão Miocárdica/patologia , Miocárdio/metabolismo , Miocárdio/patologia , Peroxidase/metabolismo , Ratos , Ratos Sprague-Dawley , Tiocianatos/metabolismo , Tiocianatos/uso terapêuticoRESUMO
Diabetic patients suffer from both cardiac lipid accumulation and an increased risk of arrhythmias and sudden cardiac death. This correlation suggests a link between diabetes induced cardiac steatosis and electrical abnormalities, however, the underlying mechanism remains unknown. We previously showed that cardiac conduction velocity slows in Zucker diabetic fatty rats and in fructose-fat fed rats, models that both exhibit prominent cardiac steatosis. The aim of this study was to investigate whether acute cardiac lipid accumulation reduces conduction velocity per se. Cardiac lipid accumulation was induced acutely by perfusing isolated rat hearts with palmitate-glucose buffer, or subacutely by fasting rats overnight. Subsequently, longitudinal cardiac conduction velocity was measured in right ventricular tissue strips, and intramyocardial triglyceride and lipid droplet content was determined by thin layer chromatography and BODIPY staining, respectively. Perfusion with palmitate-glucose buffer significantly increased intramyocardial triglyceride levels compared to perfusion with glucose (2.16 ± 0.17 (n = 10) vs. 0.92 ± 0.33 nmol/mg WW (n = 9), P < 0.01), but the number of lipid droplets was very low in both groups. Fasting of rats, however, resulted in both significantly elevated intramyocardial triglyceride levels compared to fed rats (3.27 ± 0.43 (n = 10) vs. 1.45 ± 0.24 nmol/mg WW (n = 10)), as well as a larger volume of lipid droplets (0.60 ± 0.13 (n = 10) vs. 0.21 ± 0.06% (n = 10), P < 0.05). There was no significant difference in longitudinal conduction velocity between palmitate-glucose perfused and control hearts (0.77 ± 0.025 (n = 10) vs. 0.75 m/sec ± 0.029 (n = 9)), or between fed and fasted rats (0.75 ± 0.042 m/sec (n = 10) vs. 0.79 ± 0.047 (n = 10)). In conclusion, intramyocardial lipid accumulation does not slow cardiac longitudinal conduction velocity per se. This is true for both increased intramyocardial triglyceride content, induced by palmitate-glucose perfusion, and increased intramyocardial triglyceride and lipid droplet content, generated by fasting.
Assuntos
Sistema de Condução Cardíaco/efeitos dos fármacos , Coração/efeitos dos fármacos , Miocárdio/metabolismo , Ácido Palmítico/farmacologia , Triglicerídeos/metabolismo , Animais , Sistema de Condução Cardíaco/fisiologia , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND AND AIMS: Cholesterol crystal (CC)-induced inflammation is a critical step in the development of atherosclerosis. CCs activate the complement system and induce an inflammatory response resulting in phagocytosis of the CCs, production of reactive oxygen species (ROS) and release of cytokines. The cyclodextrin 2-hydroxypropyl-ß-cyclodextrin has been found to reduce CC-induced complement activation and induce regression of established atherosclerotic plaques in a mouse model of atherosclerosis, thus inhibition of complement with cyclodextrins is a potential new strategy for treatment of inflammation during atherosclerosis. We hypothesized that other cyclodextrins, like α-cyclodextrin, may have related functions. METHODS: The effect of cyclodextrins on CC-induced complement activation, phagocytosis, and production of ROS from granulocytes and monocytes was investigated by flow cytometry and ELISA. RESULTS: We showed that α-cyclodextrin strongly inhibited CC-induced complement activation by inhibiting binding of the pattern recognition molecules C1q (via IgM) and ficolin-2. The reduced CC-induced complement activation mediated by α-cyclodextrin resulted in reduced phagocytosis and reduced ROS production in monocytes and granulocytes. Alpha-cyclodextrin was the most effective inhibitor of CC-induced complement activation, with the reduction in deposition of complement activation products being significantly different from the reduction induced by 2-hydroxypropyl-ß-cyclodextrin. We also found that α-cyclodextrin was able to dissolve CCs. CONCLUSIONS: This study identified α-cyclodextrin as a potential candidate in the search for therapeutics to prevent CC-induced inflammation in atherosclerosis.
Assuntos
Aterosclerose/tratamento farmacológico , Colesterol/metabolismo , Inflamação/tratamento farmacológico , alfa-Ciclodextrinas/farmacologia , Aterosclerose/metabolismo , Aterosclerose/patologia , Ativação do Complemento/efeitos dos fármacos , Ensaio de Imunoadsorção Enzimática , Feminino , Citometria de Fluxo , Humanos , Inflamação/metabolismo , Inflamação/patologia , Masculino , Monócitos/metabolismo , Monócitos/patologia , Fagocitose/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismoRESUMO
Drugs facilitating the cardioprotective effects of natriuretic peptides are introduced in heart failure treatment. ANP and BNP also stimulate lipolysis and increase circulating concentrations of free fatty acids (FFAs); an aspect, however, thought to be confined to primates. We examined the lipolytic effect of natriuretic peptide infusion in healthy young men and evaluated the effect in a porcine model of myocardial ischemia and reperfusion. Six young healthy normotensive men underwent infusion with ANP, BNP, or CNP for 20 min. Blood samples were collected before, during, and after infusion for measurement of FFAs. In a porcine model of myocardial ischemia and reperfusion, animals were infused for 3 h with either BNP (n = 7) or saline (n = 5). Blood samples were collected throughout the infusion period, and cardiac tissue was obtained after infusion for lipid analysis. In humans, ANP infusion dose-dependently increased the FFA concentration in plasma 2.5-10-fold (baseline vs. 0.05 µg/kg/min P < 0.002) and with BNP 1.6-3.5-fold (P = 0.001, baseline vs. 0.02 µg/kg/min) 30 min after initiation of infusion. Infusion of CNP did not affect plasma FFA. In pigs, BNP infusion induced a 3.5-fold increase in plasma FFA (P < 0.0001), which remained elevated throughout the infusion period. Triglyceride content in porcine right cardiac ventricle tissue increased â¼5.5 fold in animals infused with BNP (P = 0.02). Natriuretic peptide infusion has similar lipolytic activity in human and pig. Our data suggest that short-term infusion increases the cardiac lipid content, and that the pig is a suitable model for studies of long-term effects mediated by natriuretic peptides.
Assuntos
Fator Natriurético Atrial/metabolismo , Coração/efeitos dos fármacos , Lipólise , Modelos Animais , Miocárdio/metabolismo , Peptídeo Natriurético Encefálico/metabolismo , Triglicerídeos/metabolismo , Animais , Fator Natriurético Atrial/administração & dosagem , Fator Natriurético Atrial/farmacologia , Modelos Animais de Doenças , Ácidos Graxos não Esterificados/sangue , Ácidos Graxos não Esterificados/metabolismo , Feminino , Humanos , Infusões Intravenosas , Masculino , Isquemia Miocárdica/metabolismo , Peptídeo Natriurético Encefálico/administração & dosagem , Peptídeo Natriurético Encefálico/farmacologia , Sus scrofa/metabolismoRESUMO
Chronic kidney disease affects as much as 13% of the population, and is associated with a markedly increased risk of developing cardiovascular disease. One of the underlying reasons is accelerated development of atherosclerosis. This can be ascribed both to increased occurrence of traditional cardiovascular risk factors, and to risk factors that may be unique to patients with chronic kidney disease. The latter is reflected in the observation that the current treatment modalities, mainly directed against traditional risk factors, are insufficient to prevent cardiovascular disease in the patient with chronic kidney disease. This review discusses mechanisms accelerating uremic atherosclerosis with a specific focus on the putative roles of apolipoprotein(apo)s B and M that may be particularly important in patients with chronic kidney disease.
Assuntos
Apolipoproteínas B/metabolismo , Apolipoproteínas M/metabolismo , Aterosclerose/etiologia , Aterosclerose/metabolismo , Uremia/complicações , Animais , Aterosclerose/tratamento farmacológico , Humanos , Terapia de Alvo MolecularRESUMO
OBJECTIVE: Atherosclerotic lesions contain hypoxic areas, but the pathophysiological importance of hypoxia is unknown. Hypoxia-inducible factor-1α (HIF-1α) is a key transcription factor in cellular responses to hypoxia. We investigated the hypothesis that HIF-1α has effects on macrophage biology that promotes atherogenesis in mice. APPROACH AND RESULTS: Studies with molecular probes, immunostaining, and laser microdissection of aortas revealed abundant hypoxic, HIF-1α-expressing macrophages in murine atherosclerotic lesions. To investigate the significance of macrophage HIF-1α, Ldlr(-/-) mice were transplanted with bone marrow from mice with HIF-1α deficiency in the myeloid cells or control bone marrow. The HIF-1α deficiency in myeloid cells reduced atherosclerosis in aorta of the Ldlr(-/-) recipient mice by ≈72% (P=0.006).In vitro, HIF-1α-deficient macrophages displayed decreased differentiation to proinflammatory M1 macrophages and reduced expression of inflammatory genes. HIF-1α deficiency also affected glucose uptake, apoptosis, and migratory abilities of the macrophages. CONCLUSIONS: HIF-1α expression in macrophages affects their intrinsic inflammatory profile and promotes development of atherosclerosis.
Assuntos
Aorta Torácica/metabolismo , Doenças da Aorta/metabolismo , Aterosclerose/metabolismo , Células Espumosas/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Animais , Aorta Torácica/patologia , Doenças da Aorta/genética , Doenças da Aorta/patologia , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Apoptose , Aterosclerose/genética , Aterosclerose/patologia , Transplante de Medula Óssea , Diferenciação Celular , Hipóxia Celular , Movimento Celular , Células Cultivadas , Colesterol/metabolismo , Modelos Animais de Doenças , Progressão da Doença , Células Espumosas/patologia , Predisposição Genética para Doença , Glucose/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/deficiência , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Mediadores da Inflamação/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fenótipo , Placa Aterosclerótica , Receptores de LDL/deficiência , Receptores de LDL/genética , Transdução de SinaisRESUMO
Cholesterol crystals (CC) play an essential role in the formation of atherosclerotic plaques. CC activate the classical and the alternative complement pathways, but the role of the lectin pathway is unknown. We hypothesized that the pattern recognition molecules (PRMs) from the lectin pathway bind CC and function as an upstream innate inflammatory signal in the pathophysiology of atherosclerosis. We investigated the binding of the PRMs mannose-binding lectin (MBL), ficolin-1, ficolin-2, and ficolin-3, the associated serine proteases, and complement activation products to CC in vitro using recombinant proteins, specific inhibitors, as well as deficient and normal sera. Additionally, we examined the deposition of ficolin-2 and MBL in human carotid plaques by immunohistochemistry and fluorescence microscopy. The results showed that the lectin pathway was activated on CC by binding of ficolin-2 and MBL in vitro, resulting in activation and deposition of complement activation products. MBL bound to CC in a calcium-dependent manner whereas ficolin-2 binding was calcium-independent. No binding was observed for ficolin-1 or ficolin-3. MBL and ficolin-2 were present in human carotid plaques, and binding of MBL to CC was confirmed in vivo by immunohistochemistry, showing localization of MBL around CC clefts. Moreover, we demonstrated that IgM, but not IgG, bound to CC in vitro and that C1q binding was facilitated by IgM. In conclusion, our study demonstrates that PRMs from the lectin pathway recognize CC and provides evidence for an important role for this pathway in the inflammatory response induced by CC in the pathophysiology of atherosclerosis.
Assuntos
Aterosclerose/imunologia , Aterosclerose/fisiopatologia , Ativação do Complemento , Progressão da Doença , Lectinas/metabolismo , Lectina de Ligação a Manose/metabolismo , Cálcio/metabolismo , Estenose das Carótidas/imunologia , Colesterol/química , Colesterol/imunologia , Colesterol/metabolismo , Colesterol/farmacologia , Complemento C4/metabolismo , Cristalização , Imunofluorescência , Glicoproteínas/imunologia , Glicoproteínas/metabolismo , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/metabolismo , Imunoglobulina M/imunologia , Imunoglobulina M/metabolismo , Inflamação , Lectinas/imunologia , Lectina de Ligação a Manose/imunologia , Microscopia de Fluorescência , Receptores de Reconhecimento de Padrão/imunologia , Receptores de Reconhecimento de Padrão/metabolismo , Proteínas Recombinantes/metabolismo , FicolinasRESUMO
RATIONALE: Plasma cholesterol lowering is beneficial in patients with atherosclerosis. However, it is unknown how it affects entry and degradation of low-density lipoprotein (LDL) particles in the lesioned arterial wall. OBJECTIVE: We studied the effect of lipid-lowering therapy on LDL permeability and degradation of LDL particles in atherosclerotic aortas of mice by measuring the accumulation of iodinated LDL particles in the arterial wall. METHODS AND RESULTS: Cholesterol-fed, LDL receptor-deficient mice were treated with either an anti-Apob antisense oligonucleotide or a mismatch control antisense oligonucleotide once a week for 1 or 4 weeks before injection with preparations of iodinated LDL particles. The anti-Apob antisense oligonucleotide reduced plasma cholesterol by ≈90%. The aortic LDL permeability and degradation rates of newly entered LDL particles were reduced by ≈50% and ≈85% already after 1 week of treatment despite an unchanged pool size of aortic iodinated LDL particles. In contrast, the size, foam cell content, and aortic pool size of iodinated LDL particles of aortic atherosclerotic plaques were not reduced until after 4 weeks of treatment with the anti-Apob antisense oligonucleotide. CONCLUSIONS: Improved endothelial barrier function toward the entry of plasma LDL particles and diminished aortic degradation of the newly entered LDL particles precede plaque regression.
Assuntos
Aorta/metabolismo , Doenças da Aorta/terapia , Apolipoproteínas B/metabolismo , Aterosclerose/terapia , Lipoproteínas LDL/metabolismo , Oligonucleotídeos Antissenso/administração & dosagem , Animais , Aorta/patologia , Doenças da Aorta/genética , Doenças da Aorta/metabolismo , Doenças da Aorta/patologia , Apolipoproteína B-100 , Apolipoproteínas B/genética , Aterosclerose/genética , Aterosclerose/metabolismo , Aterosclerose/patologia , Permeabilidade Capilar , Colesterol na Dieta/sangue , Dieta Hiperlipídica , Modelos Animais de Doenças , Feminino , Células Espumosas/metabolismo , Humanos , Lipoproteínas LDL/administração & dosagem , Lipoproteínas LDL/sangue , Masculino , Camundongos Knockout , Oligonucleotídeos Antissenso/genética , Oligonucleotídeos Antissenso/metabolismo , Pinocitose , Placa Aterosclerótica , Proteólise , Receptores de LDL/deficiência , Receptores de LDL/genética , Indução de Remissão , Fatores de TempoRESUMO
BACKGROUND: Type 2 diabetes is associated with abnormal electrical conduction and sudden cardiac death, but the pathogenic mechanism remains unknown. This study describes electrophysiological alterations in a diet-induced pre-diabetic rat model and examines the underlying mechanism. METHODS: Sprague-Dawley rats were fed either high-fat diet and fructose water or normal chow and water for 6 weeks. The electrophysiological properties of the whole heart was analyzed by in vivo surface ECG recordings, as wells as ex vivo in Langendorff perfused hearts during baseline, ischemia and reperfussion. Conduction velocity was examined in isolated tissue strips. Ion channel and gap junction conductances were analyzed by patch-clamp studies in isolated cardiomyocytes. Fibrosis was examined by Masson's Trichrome staining and thin-layer chromatography was used to analyze cardiac lipid content. Connexin43 (Cx43) expression and distribution was examined by western blotting and immunofluorescence respectively. RESULTS: Following 6 weeks of feeding, fructose-fat fed rats (FFFRs) showed QRS prolongation compared to controls (16.1 ± 0.51 (n = 6) vs. 14.7 ± 0.32 ms (n = 4), p < 0.05). Conduction velocity was slowed in FFFRs vs. controls (0.62 ± 0.02 (n = 13) vs. 0.79 ± 0.06 m/s (n = 11), p < 0.05) and Langendorff perfused FFFR hearts were more prone to ventricular fibrillation during reperfusion following ischemia (p < 0.05). The patch-clamp studies revealed no changes in Na(+) or K(+) currents, cell capacitance or gap junctional coupling. Cx43 expression was also unaltered in FFFRs, but immunofluorescence demonstrated an increased fraction of Cx43 localized at the intercalated discs in FFFRs compared to controls (78 ± 3.3 (n = 5) vs. 60 ± 4.2 % (n = 6), p < 0.01). No fibrosis was detected but FFFRs showed a significant increase in cardiac triglyceride content (1.93 ± 0.19 (n = 12) vs. 0.77 ± 0.13 nmol/mg (n = 12), p < 0.0001). CONCLUSION: Six weeks on a high fructose-fat diet cause electrophysiological changes, which leads to QRS prolongation, decreased conduction velocity and increased arrhythmogenesis during reperfusion. These alterations are not explained by altered gap junctional coupling, Na(+), or K(+) currents, differences in cell size or fibrosis.
Assuntos
Arritmias Cardíacas/fisiopatologia , Sistema de Condução Cardíaco/fisiopatologia , Isquemia Miocárdica/fisiopatologia , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Estado Pré-Diabético/fisiopatologia , Animais , Conexina 43/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Dieta Hiperlipídica , Modelos Animais de Doenças , Eletrocardiografia , Frutose , Junções Comunicantes/metabolismo , Masculino , Contração Miocárdica , Reperfusão Miocárdica , Técnicas de Patch-Clamp , Canais de Potássio/metabolismo , Ratos , Ratos Sprague-Dawley , Canais de Sódio/metabolismo , Triglicerídeos/metabolismoRESUMO
In the 30 years since the identification of the natriuretic peptides, their involvement in regulating fluid and blood pressure has become firmly established. Data indicating a role for these hormones in lifestyle-related metabolic and cardiovascular disorders have also accumulated over the past decade. Dysregulation of the natriuretic peptide system has been associated with obesity, glucose intolerance, type 2 diabetes mellitus, and essential hypertension. Moreover, the natriuretic peptides have been implicated in the protection against atherosclerosis, thrombosis, and myocardial ischaemia. All these conditions can coexist and potentially lead to heart failure, a syndrome associated with a functional natriuretic peptide deficiency despite high circulating concentrations of immunoreactive peptides. Therefore, dysregulation of the natriuretic peptide system, a 'natriuretic handicap', might be an important factor in the initiation and progression of metabolic dysfunction and its accompanying cardiovascular complications. This Review provides a summary of the natriuretic peptide system and its involvement in these cardiometabolic conditions. We propose that these peptides might have an integrating role in lifestyle-related metabolic and cardiovascular disorders.
Assuntos
Doenças Cardiovasculares/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Intolerância à Glucose/metabolismo , Peptídeos Natriuréticos/metabolismo , Obesidade/metabolismo , Biomarcadores/metabolismo , HumanosRESUMO
BACKGROUND: Lipid accumulation in skeletal muscle is associated with impaired insulin sensitivity in type 2 diabetes. In cardiac myocytes, lipoprotein secretion controlled by apolipoproteinB (apoB) and microsomal triglyceride transfer protein (MTP) affects lipid homeostasis. DESIGN: In this study, we investigated whether expression of a human apoB transgene affects triglyceride accumulation and insulin sensitivity in skeletal muscle in fat fed obese mice. RESULTS: Expression of apoB and MTP mRNA and the human apoB transgene was seen in skeletal muscle of the transgene mice. Human apoB transgenic mice accumulated 28% less triglycerides in skeletal myocytes after one year of fat-feeding as compared with WT mice (32 ± 5, n = 10 vs. 44 ± 4 nmol/mg ww, n = 13, p = 0.04). Moreover, expression of human apoB in fat-fed mice was associated with 32% (p = 0.02) and 37% (p = 0.01) lower plasma insulin levels after 9 and 12 months, respectively, improved intra peritoneal glucose tolerance after 6 months, and a trend towards increased insulin-stimulated glucose uptake in isolated skeletal muscle. CONCLUSIONS: The data suggests that overexpression of apoB decreases skeletal muscle lipid accumulation and attenuates peripheral insulin resistance in obese mice.
Assuntos
Apolipoproteínas B/genética , Músculo Esquelético/fisiologia , Obesidade/metabolismo , Triglicerídeos/metabolismo , Animais , Apolipoproteínas B/metabolismo , Glicemia/metabolismo , Regulação da Expressão Gênica , Humanos , Insulina/metabolismo , Resistência à Insulina , Secreção de Insulina , Metabolismo dos Lipídeos/genética , Fígado/metabolismo , Masculino , Camundongos Obesos , Camundongos Transgênicos , Obesidade/etiologia , Obesidade/fisiopatologia , Pâncreas/metabolismoRESUMO
We have shown previously that inhibition of small conductance Ca(2+)-activated K(+) (SK) channels is antiarrhythmic in models of acutely induced atrial fibrillation (AF). These models, however, do not take into account that AF derives from a wide range of predisposing factors, the most prevalent being hypertension. In this study we assessed the effects of two different SK channel inhibitors, NS8593 and UCL1684, in aging, spontaneously hypertensive rats to examine their antiarrhythmic properties in a setting of hypertension-induced atrial remodeling. Male spontaneously hypertensive rats and the normotensive Wistar-Kyoto rat strain were divided in 2×3 groups of animals aged 3, 8, and 11 months, respectively. The animals were randomly assigned to treatment with NS8593, UCL1684, or vehicle, and open chest in vivo experiments including burst pacing-induced AF were performed. The aging spontaneously hypertensive rats were more vulnerable to AF induction both by S2 stimulation and burst pacing. Vehicle affected neither the atrial effective refractory period nor AF duration. SK channel inhibition with NS8593 and UCL1684 significantly increased the atrial effective refractory period and decreased AF duration in both the normotensive and hypertensive strains with no decline in efficacy as age increased. In conclusion, SK channel inhibition with NS8593 and UCL1684 possesses antiarrhythmic properties in a rat in vivo model of paroxysmal AF with hypertension-induced atrial remodeling. The present results support the notion that SK channels may offer a promising new therapeutic target in the treatment of AF.
Assuntos
Fibrilação Atrial/prevenção & controle , Hipertensão/fisiopatologia , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio Cálcio-Ativados/antagonistas & inibidores , 1-Naftilamina/administração & dosagem , 1-Naftilamina/análogos & derivados , 1-Naftilamina/farmacologia , Fatores Etários , Alcanos/administração & dosagem , Alcanos/farmacologia , Animais , Antiarrítmicos/administração & dosagem , Antiarrítmicos/farmacologia , Fibrilação Atrial/fisiopatologia , Estimulação Cardíaca Artificial , Modelos Animais de Doenças , Humanos , Injeções Intravenosas , Masculino , Bloqueadores dos Canais de Potássio/administração & dosagem , Canais de Potássio Cálcio-Ativados/fisiologia , Compostos de Quinolínio/administração & dosagem , Compostos de Quinolínio/farmacologia , Distribuição Aleatória , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , Especificidade da Espécie , Fatores de TempoRESUMO
Obesity causes lipid accumulation in the heart and may lead to lipotoxic heart disease. Traditionally, the size of the cardiac triglyceride pool is thought to reflect the balance between uptake and beta-oxidation of fatty acids. However, triglycerides can also be exported from cardiomyocytes via secretion of apolipoproteinB-containing (apoB) lipoproteins. Lipoprotein formation depends on expression of microsomal triglyceride transfer protein (MTP); the mouse expresses two isoforms of MTP, A and B. Since many aspects of the link between obesity-induced cardiac disease and cardiac lipid metabolism remain unknown, we investigated how cardiac lipoprotein synthesis affects cardiac expression of triglyceride metabolism-controlling genes, insulin sensitivity, and function in obese mice. Heart-specific ablation of MTP-A in mice using Cre-loxP technology impaired upregulation of MTP expression in response to increased fatty acid availability during fasting and fat feeding. This resulted in cardiac triglyceride accumulation but unaffected cardiac insulin-stimulated glucose uptake. Long-term fat-feeding of male C57Bl/6 mice increased cardiac triglycerides, induced cardiac expression of triglyceride metabolism-controlling genes and attenuated heart function. Abolishing cardiac triglyceride accumulation in fat-fed mice by overexpression of an apoB transgene in the heart prevented the induction of triglyceride metabolism-controlling genes and improved heart function. The results suggest that in obesity, the physiological increase of cardiac MTP expression serves to attenuate cardiac triglyceride accumulation albeit without major effects on cardiac insulin sensitivity. Nevertheless, the data suggest that genetically increased lipoprotein secretion prevents development of obesity-induced lipotoxic heart disease.
Assuntos
Proteínas de Transporte/genética , Miocárdio/metabolismo , Obesidade/metabolismo , Triglicerídeos/metabolismo , Animais , Apolipoproteínas B/genética , Apolipoproteínas B/metabolismo , Proteínas de Transporte/metabolismo , Humanos , Insulina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Camundongos Obesos , Camundongos Transgênicos , Obesidade/genéticaRESUMO
Wild-type mice normally do not develop atherosclerosis, unless fed cholic acid. Uremia is proinflammatory and increases atherosclerosis 6- to 10-fold in apolipoprotein E-deficient mice. This study examined the effect of uremia on lipoproteins, vascular inflammation, and atherosclerosis in wild-type C57BL/6J mice. Uremia was induced by nephrectomy (NX) and increased plasma urea and creatinine concentrations 2.5- to 4.5-fold; control mice were sham operated. After NX, mice were fed a Western-type diet or the same diet with 0.5% cholic acid. Cholic acid-fed NX mice did not thrive and were killed. In NX mice fed the Western-type diet (n = 7), the total plasma cholesterol concentration was similar to that in sham mice (n = 11), but on gel filtration the LDL/HDL cholesterol ratio was increased. HDL from NX mice contained more serum amyloid A and triglycerides and less cholesterol than HDL from sham mice. Plasma concentrations of sICAM-1 and sVCAM-1 and aortic mRNA expression of ICAM-1 and VCAM-1 did not differ between NX and sham mice. Twenty-six weeks after NX, the average oil red O-stained area of the aortic root was similar in NX and sham mice fed the Western-type diet, while it was increased in cholic acid-fed sham mice. The results suggest that moderate uremia neither induces aortic inflammation nor atherosclerosis in C57BL/6J mice despite increased LDL/HDL cholesterol ratio and altered HDL composition.
Assuntos
Aterosclerose/metabolismo , Lipoproteínas HDL/metabolismo , Uremia/metabolismo , Vasculite/metabolismo , Animais , Aorta Torácica/metabolismo , Apolipoproteína A-I/metabolismo , Apolipoproteínas B/metabolismo , Aterosclerose/induzido quimicamente , Aterosclerose/patologia , Colesterol na Dieta/efeitos adversos , Colesterol na Dieta/farmacologia , Ácido Cólico/efeitos adversos , Ácido Cólico/farmacologia , Molécula 1 de Adesão Intercelular/metabolismo , Rim/efeitos dos fármacos , Rim/fisiologia , Fígado/efeitos dos fármacos , Fígado/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Nefrectomia , RNA Mensageiro/metabolismo , Proteína Amiloide A Sérica/metabolismo , Uremia/etiologia , Uremia/patologia , Molécula 1 de Adesão de Célula Vascular/metabolismo , Vasculite/induzido quimicamente , Vasculite/patologiaRESUMO
Endothelial lipase (EL) is expressed in endothelial cells, and affects plasma lipoprotein metabolism by hydrolyzing phospholipids in HDL. To determine the cellular expression of EL mRNA and protein in human atherosclerotic lesions, we performed in situ hybridization and immunohistochemical studies on sections of carotid endarterectomy specimens from patients with symptomatic cerebrovascular disease. In each of eight patients, EL mRNA and/or protein were seen in areas between the necrotic core and the fibrotic cap where they colocalized with LPL and macrophage-specific CD68. Moreover, there was a positive association between the expression of EL mRNA and CD68 mRNA in plaques from 26 patients. The impact of differentiation from monocytes into macrophages, and subsequently foam cells (by incubation with acetylated LDL) on expression was studied using THP-1 monocytes and primary human monocytes. EL mRNA expression increased markedly when either type of monocytes was differentiated into macrophages. Upon further differentiation into foam cells EL mRNA decreased whereas protein levels remained high compared to monocytes. In conclusion, macrophages in advanced human atherosclerotic lesions display high levels of EL expression, and the level of EL expression varies greatly during transformation of blood monocytes into foam cells.
Assuntos
Estenose das Carótidas/fisiopatologia , Células Espumosas/metabolismo , Lipase/metabolismo , Macrófagos/metabolismo , Idoso , Estudos de Casos e Controles , Linhagem Celular Tumoral , Células Cultivadas , Feminino , Humanos , Imuno-Histoquímica , Hibridização In Situ , Masculino , Pessoa de Meia-IdadeRESUMO
Obesity may confer cardiac dysfunction due to lipid accumulation in cardiomyocytes. To test this idea, we examined whether obese ob/ob mice display heart lipid accumulation and cardiac dysfunction. Ob/ob mouse hearts had increased expression of genes mediating extracellular generation, transport across the myocyte cell membrane, intracellular transport, mitochondrial uptake, and beta-oxidation of fatty acids compared with ob/+ mice. Accordingly, ob/ob mouse hearts contained more triglyceride (6.8 +/- 0.4 vs. 2.3 +/- 0.4 microg/mg; P < 0.0005) than ob/+ mouse hearts. Histological examinations showed marked accumulation of neutral lipid droplets within cardiac myocytes but not increased deposition of collagen between myocytes in ob/ob compared with ob/+ mouse hearts. On echocardiography, the ratio of E to A transmitral flow velocities (an indicator of diastolic function) was 1.8 +/- 0.1 in ob/ob mice and 2.5 +/- 0.1 in ob/+ mice (P = 0.0001). In contrast, the indexes of systolic function and heart brain natriuretic peptide mRNA expression were only marginally affected and unaffected, respectively, in ob/ob compared with ob/+ mice. The results suggest that ob/ob mouse hearts have increased expression of cardiac gene products that stimulate myocyte fatty acid uptake and triglyceride storage and accumulate neutral lipids within the cardiac myocytes. The results also suggest that the cardiac lipid accumulation is paralleled by cardiac diastolic dysfunction in ob/ob mice.