RESUMO
BACKGROUND: Computed tomography (CT) offers pulmonary volumetric quantification but is not commonly used in healthy individuals due to radiation concerns. Chronic airflow limitation (CAL) is one of the diagnostic criteria for chronic obstructive pulmonary disease (COPD), where early diagnosis is important. Our aim was to present reference values for chest CT volumetric and radiodensity measurements and explore their potential in detecting early signs of CAL. METHODS: From the population-based Swedish CArdioPulmonarybioImage Study (SCAPIS), 294 participants aged 50-64, were categorized into non-CAL (n = 258) and CAL (n = 36) groups based on spirometry. From inspiratory and expiratory CT images we compared lung volumes, mean lung density (MLD), percentage of low attenuation volume (LAV%) and LAV cluster volume between groups, and against reference values from static pulmonary function test (PFT). RESULTS: The CAL group exhibited larger lung volumes, higher LAV%, increased LAV cluster volume and lower MLD compared to the non-CAL group. Lung volumes significantly deviated from PFT values. Expiratory measurements yielded more reliable results for identifying CAL compared to inspiratory. Using a cut-off value of 0.6 for expiratory LAV%, we achieved sensitivity, specificity and positive/negative predictive values of 72%, 85% and 40%/96%, respectively. CONCLUSION: We present volumetric reference values from inspiratory and expiratory chest CT images for a middle-aged healthy cohort. These results are not directly comparable to those from PFTs. Measures of MLD and LAV can be valuable in the evaluation of suspected CAL. Further validation and refinement are necessary to demonstrate its potential as a decision support tool for early detection of COPD.
Assuntos
Medidas de Volume Pulmonar , Pulmão , Valor Preditivo dos Testes , Doença Pulmonar Obstrutiva Crônica , Espirometria , Humanos , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/fisiopatologia , Doença Pulmonar Obstrutiva Crônica/diagnóstico por imagem , Masculino , Feminino , Pulmão/diagnóstico por imagem , Pulmão/fisiopatologia , Medidas de Volume Pulmonar/métodos , Reprodutibilidade dos Testes , Suécia , Tomografia Computadorizada por Raios X/métodos , Volume Expiratório Forçado , Diagnóstico PrecoceRESUMO
BACKGROUND: Multiple circulatory factors are increased in heart failure (HF). Many have been linked to cardiac and/or skeletal muscle tissue processes, which in turn might influence physical activity and/or capacity during HF. This study aimed to provide a better understanding of the mechanisms linking HF with the loss of peripheral function. METHODS AND RESULTS: Physical capacity measured by maximum oxygen uptake, myocardial function (measured by echocardiography), physical activity (measured by accelerometry), and mortality data was collected for patients with severe symptomatic heart failure an ejection fraction < 35% (n = 66) and controls (n = 28). Plasma circulatory factors were quantified using a multiplex immunoassay. Multivariate (orthogonal projections to latent structures discriminant analysis) and univariate analyses identified many factors that differed significantly between HF and control subjects, mainly involving biological functions related to cell growth and cell adhesion, extracellular matrix organization, angiogenesis, and inflammation. Then, using principal component analysis, links between circulatory factors and physical capacity, daily physical activity, and myocardial function were identified. A subset of ten biomarkers differentially expressed in patients with HF vs controls covaried with physical capacity, daily physical activity, and myocardial function; eight of these also carried prognostic value. These included established plasma biomarkers of HF, such as NT-proBNP and ST2 along with recently identified factors such as GDF15, IGFBP7, and TfR, as well as a new factor, galectin-4. CONCLUSIONS: These findings reinforce the importance of systemic circulatory factors linked to hemodynamic stress responses and inflammation in the pathogenesis and progress of HF disease. They also support established biomarkers for HF and suggest new plausible markers.
Assuntos
Insuficiência Cardíaca/metabolismo , Consumo de Oxigênio , Oxigênio/metabolismo , Volume Sistólico/fisiologia , Idoso , Biomarcadores/sangue , Ecocardiografia , Feminino , Seguimentos , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Estudos Prospectivos , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Thoracic epidural analgesia (TEDA) was offered to patients with refractory angina pectoris. Our primary objectives were to evaluate TEDAs´ influence on quality of life (QoL, base for power analysis), and hypothesising that TEDA with bupivacaine during 1 month counteracts exercise-induced myocardial hypoperfusion and increase physical performance. METHODS: Patients with refractory angina and exercise inducible hypoperfusion, as demonstrated by myocardial perfusion imaging (MPI), were randomised to 1-month treatment with TEDA with bupivacaine (B-group, n = 9) or saline (P-group, n = 10) in a double-blind fashion. MPI and bicycle ergometry were performed before TEDA and after 1 month while subjective QoL on a visual analogue scale (VAS) reported by the patients was checked weekly. RESULTS: During this month VAS (mean [95%CI]) increased similarly in both groups (B-group from 33 [18-50] to 54 [30-78] P < 0.05; P-group from 40 [19-61] to 48 [25-70] P < 0.05). The B-group reduced their exertional-induced myocardial hypoperfusion (from 32% [12-52] to 21% [3-39]; n = 9; P < 0.05), while the P-group showed no significant change (before 21% [6-35]; at 1 month 23% [6-40]; n = 10). MPI at rest did not change and no improvement in physical performance was detected in neither of the groups. CONCLUSIONS: In refractory angina, TEDA with bupivacaine inhibits myocardial ischaemia in contrast to TEDA with saline. Regardless of whether bupivacaine or saline is applied intermittently every day, TEDA during 1 month improves the quality of life and reduces angina, even when physical performance remains low. A significant placebo effect has to be considered.
Assuntos
Analgesia Epidural/métodos , Angina Pectoris/complicações , Angina Pectoris/tratamento farmacológico , Exercício Físico , Isquemia Miocárdica/tratamento farmacológico , Isquemia Miocárdica/etiologia , Idoso , Idoso de 80 Anos ou mais , Anestésicos Locais/administração & dosagem , Anestésicos Locais/uso terapêutico , Angina Pectoris/psicologia , Bupivacaína/administração & dosagem , Bupivacaína/uso terapêutico , Método Duplo-Cego , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Isquemia Miocárdica/psicologia , Medição da Dor , Imagem de Perfusão , Desempenho Psicomotor , Qualidade de VidaRESUMO
Enhanced external counterpulsation (EECP) is a non-invasive treatment in which leg cuff compressions increase diastolic aortic pressure and coronary perfusion. EECP is offered to patients with refractory angina pectoris and increases physical capacity. Benefits in heart failure patients have been noted, but EECP is still considered to be experimental and its effects must be confirmed. The mechanism of action is still unclear. The aim of this study was to evaluate the effect of EECP on skeletal muscle gene expression and physical performance in patients with severe heart failure. Patients (n = 9) in NYHA III-IV despite pharmacological therapy were subjected to 35 h of EECP during 7 weeks. Before and after, lateral vastus muscle biopsies were obtained, and functional capacity was evaluated with a 6-min walk test. Skeletal muscle gene expression was evaluated using Affymetrix Hugene 1.0 arrays. Maximum walking distance increased by 15%, which is in parity to that achieved after aerobic exercise training in similar patients. Skeletal muscle gene expression analysis using Ingenuity Pathway Analysis showed an increased expression of two networks of genes with FGF-2 and IGF-1 as central regulators. The increase in gene expression was quantitatively small and no overlap with gene expression profiles after exercise training could be detected despite adequate statistical power. EECP treatment leads to a robust improvement in walking distance in patients with severe heart failure and does induce a skeletal muscle transcriptional response, but this response is small and with no significant overlap with the transcriptional signature seen after exercise training.
Assuntos
Contrapulsação/métodos , Insuficiência Cardíaca/terapia , Músculo Quadríceps/irrigação sanguínea , Idoso , Aorta/fisiopatologia , Pressão Arterial , Circulação Coronária , Contrapulsação/instrumentação , Feminino , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica , Redes Reguladoras de Genes , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/fisiopatologia , Humanos , Extremidade Inferior , Masculino , Pessoa de Meia-Idade , Análise de Sequência com Séries de Oligonucleotídeos , Músculo Quadríceps/metabolismo , Fluxo Sanguíneo Regional , Índice de Gravidade de Doença , Fatores de Tempo , Transcriptoma , Resultado do TratamentoRESUMO
AIM: RhoA/Rho-associated kinase and arginase are implicated in vascular complications in diabetes. This study investigated whether RhoA/Rho-associated kinase and arginase inhibition protect from myocardial ischaemia-reperfusion injury in type 1 diabetes and the mechanisms behind these effects. METHODS: Rats with streptozotocin-induced type 1 diabetes and non-diabetic rats were subjected to 30 min myocardial ischaemia and 2 h reperfusion after being randomized to treatment with (1) saline, (2) RhoA/Rho-associated kinase inhibitor hydroxyfasudil, (3) nitric oxide synthase inhibitor NG-monomethyl-l-arginine monoacetate followed by hydroxyfasudil, (4) arginase inhibitor N-omega-hydroxy-nor-l-arginine, (5) NG-monomethyl-l-arginine monoacetate followed by N-omega-hydroxy-nor-l-arginine or (6) NG-monomethyl-l-arginine monoacetate given intravenous before ischaemia. RESULTS: Myocardial arginase activity, arginase 2 expression and RhoA/Rho-associated kinase activity were increased in type 1 diabetes ( p < 0.05). RhoA/Rho-associated kinase inhibition and arginase inhibition significantly reduced infarct size in diabetic and non-diabetic rats ( p < 0.001). The cardioprotective effects of hydroxyfasudil and N-omega-hydroxy-nor-l-arginine in diabetes were abolished by nitric oxide synthase inhibition. RhoA/Rho-associated kinase inhibition attenuated myocardial arginase activity in diabetic rats via a nitric oxide synthase-dependent mechanism. CONCLUSION: Inhibition of either RhoA/Rho-associated kinase or arginase protects from ischaemia-reperfusion injury in rats with type 1 diabetes via a nitric oxide synthase-dependent pathway. These results suggest that inhibition of RhoA/Rho-associated kinase and arginase constitutes a potential therapeutic strategy to protect the diabetic heart against ischaemia-reperfusion injury.
Assuntos
1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/análogos & derivados , Arginase/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Tipo 1/tratamento farmacológico , Infarto do Miocárdio/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miocárdio/enzimologia , Óxido Nítrico Sintase/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Quinases Associadas a rho/antagonistas & inibidores , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/farmacologia , Animais , Arginase/antagonistas & inibidores , Arginina/análogos & derivados , Arginina/farmacologia , Citoproteção , Diabetes Mellitus Experimental/enzimologia , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 1/enzimologia , Diabetes Mellitus Tipo 1/patologia , Quimioterapia Combinada , Masculino , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/enzimologia , Traumatismo por Reperfusão Miocárdica/patologia , Miocárdio/patologia , Óxido Nítrico Sintase/antagonistas & inibidores , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , ômega-N-Metilarginina/farmacologia , Proteínas rho de Ligação ao GTP/metabolismo , Quinases Associadas a rho/metabolismoRESUMO
AIMS: Patients with heart failure often display a distinct pattern of walking characterized by short step-length and frequent short pauses. In the current study we sought to explore if qualitative aspects of movement have any additive value to established factors to predict all-cause mortality in patients with advanced heart failure. METHODS AND RESULTS: 60 patients with advanced heart failure (NYHA III, peak VO2 <20 ml/kg and LVEF <35%) underwent symptom-limited CPX, echocardiography and routine chemistry. Physical activity was assessed using an accelerometer worn attached to the waist during waking hours for 7 consecutive days. The heart-failure survival score (HFSS) was calculated for each patient. All accelerometer-derived variables were analyzed with regard to all-cause mortality and added to a baseline model utilizing HFSS scores. HFSS score was significantly associated with the incidence of death (P<0.001; c-index 0.71; CI, 0.67-0.73). The addition of peak skewness to the HFSS model significantly improved the predictive ability with an increase in c-index to 0.74 (CI, 0.69-0.78), likelihood ratio P<0.02, establishing skewness as a predictor of increased event rates when accounting for baseline risk. CONCLUSION: The feature skewness, a measure of asymmetry in the intensity level of periods of high physical activity, was identified to be predictive of all-cause mortality independent of the established prognostic model-HFSS and peak VO2. The findings from the present study emphasize the use of accelerometer analysis in clinical practice to make more accurate prognoses in addition to extract features of physical activity relevant to functional classification.
Assuntos
Acelerometria , Insuficiência Cardíaca , Modelos Biológicos , Atividade Motora , Caminhada , Idoso , Idoso de 80 Anos ou mais , Intervalo Livre de Doença , Feminino , Insuficiência Cardíaca/mortalidade , Insuficiência Cardíaca/fisiopatologia , Humanos , Masculino , Taxa de SobrevidaRESUMO
OBJECTIVES: Quantification of myocardial perfusion by contrast echocardiography remains a challenge. Existing imaging phantoms used to evaluate the performance of ultrasound scanners do not comply with perfusion basics in the myocardium, where perfusion and motion are inherently coupled. To contribute toward an improvement, we developed a contrast echocardiographic perfusion imaging platform based on an isolated rat heart coupled to an ultrasound scanner. METHODS: Perfusion was assessed by using 3 different types of contrast agents: dextran-based Promiten (Meda AB, Solna, Sweden), phospholipid-shelled SonoVue (Bracco Diagnostics, Inc, Princeton, NJ), and polymer-shelled MB-pH5-RT, developed in-house. The myocardial video intensity was monitored over time from contrast agent administration to peak, and 2 characteristic constants were calculated by using an exponential fit: A, representing capillary volume; and ß, representing inflow velocity. RESULTS: Acquired experimental evidence demonstrates that the application of all 3 contrast agents allows sonographic estimation of myocardial perfusion in the isolated rat heart. Video intensity maps show that an increase in contrast concentration increases the late-plateau values, A, mimicking increased capillary volume. Estimated values of the flow, proportional to A × ß, increase when the pressure of the perfusate column increases from 80 to 110 cm of water. This finding is in agreement with the true values of the coronary flow increase measured by a flowmeter attached to the aortic cannula. CONCLUSIONS: The contrast echocardiographic perfusion imaging platform described holds promise for standardized evaluation and optimization of contrast perfusion ultrasound imaging in which real-time inflow curves at low acoustic power semiquantitatively reflect coronary flow.
Assuntos
Meios de Contraste , Dextranos , Ecocardiografia/instrumentação , Preparação de Coração Isolado/instrumentação , Imagem de Perfusão do Miocárdio/instrumentação , Fosfolipídeos , Hexafluoreto de Enxofre , Animais , Ecocardiografia/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Aumento da Imagem/instrumentação , Aumento da Imagem/métodos , Preparação de Coração Isolado/métodos , Masculino , Imagem de Perfusão do Miocárdio/métodos , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
The current study describes novel multifunctional polymer-shelled microbubbles (MBs) loaded with nitric oxide (NO) for integrated therapeutic and diagnostic applications (ie, theranostics) of myocardial ischemia. We used gas-filled MBs with an average diameter of 4 µm stabilized by a biocompatible shell of polyvinyl alcohol. In vitro acoustic tests showed sufficient enhancement of the backscattered power (20 dB) acquired from the MBs' suspension. The values of attenuation coefficient (0.8 dB/cm MHz) and phase velocities (1,517 m/s) were comparable with those reported for the soft tissue. Moreover, polymer MBs demonstrate increased stability compared with clinically approved contrast agents with a fracture threshold of about 900 kPa. In vitro chemiluminescence measurements demonstrated that dry powder of NO-loaded MBs releases its gas content in about 2 hours following an exponential decay profile with an exponential time constant equal to 36 minutes. The application of high-power ultrasound pulse (mechanical index =1.2) on the MBs resuspended in saline decreases the exponential time constant from 55 to 4 minutes in air-saturated solution and from 17 to 10 minutes in degassed solution. Thus, ultrasound-triggered release of NO is achieved. Cytotoxicity tests indicate that phagocytosis of the MBs by macrophages starts within 6-8 hours. This is a suitable time for initial diagnostics, treatment, and monitoring of the therapeutic effect using a single injection of the proposed multifunctional MBs.
Assuntos
Meios de Contraste/química , Óxido Nítrico/farmacologia , Nanomedicina Teranóstica , Ultrassom/métodos , Química Farmacêutica , Meios de Contraste/efeitos adversos , Equipamentos e Provisões , Gases , Humanos , Técnicas In Vitro , Macrófagos/efeitos dos fármacos , Microbolhas , Isquemia Miocárdica/diagnóstico , Isquemia Miocárdica/tratamento farmacológico , Óxido Nítrico/química , Tamanho da Partícula , Fagocitose , PósRESUMO
BACKGROUND: Pharmacological inhibition of arginase and remote ischemic perconditioning (RIPerc) are known to protect the heart against ischemia/reperfusion (IR) injury. PURPOSE: The objective of this study was to investigate whether (1) peroxynitrite-mediated RhoA/Rho associated kinase (ROCK) signaling pathway contributes to arginase upregulation following myocardial IR; (2) the inhibition of this pathway is involved as a cardioprotective mechanism of remote ischemic perconditioning and (3) the influence of diabetes on these mechanisms. METHODS: Anesthetized rats were subjected to 30 min left coronary artery ligation followed by 2 h reperfusion and included in two protocols. In protocol 1 rats were randomized to 1) control IR, 2) RIPerc induced by bilateral femoral artery occlusion for 15 min during myocardial ischemia, 3) RIPerc and administration of the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA), 4) administration of the ROCK inhibitor hydroxyfasudil or 5) the peroxynitrite decomposition catalyst FeTPPS. In protocol 2 non-diabetic and type 1 diabetic rats were randomosed to IR or RIPerc as described above. RESULTS: Infarct size was significantly reduced in rats treated with FeTPPS, hydroxyfasudil and RIPerc compared to controls (P<0.001). FeTPPS attenuated both ROCK and arginase activity (P<0.001 vs. control). Similarly, RIPerc reduced arginase and ROCK activity, peroxynitrite formation and enhanced phospho-eNOS expression (P<0.05 vs. control). The cardioprotective effect of RIPerc was abolished by L-NMMA. The protective effect of RIPerc and its associated changes in arginase and ROCK activity were abolished in diabetes. CONCLUSION: Arginase is activated by peroxynitrite/ROCK signaling cascade in myocardial IR. RIPerc protects against IR injury via a mechanism involving inhibition of this pathway and enhanced eNOS activation. The beneficial effect and associated molecular changes of RIPerc is abolished in type 1 diabetes.
Assuntos
Arginase/metabolismo , Diabetes Mellitus Experimental/metabolismo , Precondicionamento Isquêmico , Traumatismo por Reperfusão Miocárdica/metabolismo , Ácido Peroxinitroso/metabolismo , Quinases Associadas a rho/metabolismo , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/análogos & derivados , 1-(5-Isoquinolinasulfonil)-2-Metilpiperazina/farmacologia , Animais , Inibidores Enzimáticos/farmacologia , Masculino , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , ômega-N-Metilarginina/farmacologiaRESUMO
Two distinct enzymes of arginase (1 and 2) are critically regulating nitric oxide (NO) bioavailability by competing with NO synthase for their common substrate l-arginine. Increased expression and activity of arginase is observed in atherosclerosis and myocardial ischemia-reperfusion (I/R). Several studies have demonstrated a key pathophysiological role of increased activity of arginase during I/R. Pharmacological inhibition of arginase results in restoration of NO availability and salvage of myocardium during I/R. Arginase inhibition might be a promising therapeutic strategy for the limitation of myocardial injury in acute myocardial infarction. Current understanding of the role of arginase and efficacy of arginase inhibition during myocardial I/R is reviewed in the present article.
Assuntos
Arginase/metabolismo , Traumatismo por Reperfusão Miocárdica/metabolismo , Animais , Humanos , Óxido Nítrico/metabolismoRESUMO
BACKGROUND: Reduced bioavailability of nitric oxide (NO) is a key factor contributing to myocardial ischemia and reperfusion injury. The mechanism behind the reduction of NO is related to deficiency of the NO synthase (NOS) substrate L-arginine and cofactor tetrahydrobiopterin (BH4) resulting in NOS uncoupling. The aim of the study was to investigate if the combination of L-arginine and BH4 given iv or intracoronary before reperfusion protects from reperfusion injury. METHODS: Sprague-Dawley rats and pigs were subjected to myocardial ischemia and reperfusion. Rats received vehicle, L-arginine, BH4, L-arginine+BH4 with or without the NOS-inhibitor L-NMMA iv 5 min before reperfusion. Pigs received infusion of vehicle, L-arginine, BH4 or L-arginine+BH4 into the left main coronary artery for 30 min starting 10 min before reperfusion. RESULTS: Infarct size was significantly smaller in the rats (50 ± 2%) and pigs (54 ± 5%) given L-arginine+BH4 in comparison with the vehicle groups (rats 65 ± 3% and pigs 86 ± 5%, P<0.05). Neither L-arginine nor BH4 alone significantly reduced infarct size. Administration of L-NMMA abrogated the cardioprotective effect of L-arginine+BH4. Myocardial BH4 levels were 3.5- to 5-fold higher in pigs given L-arginine+BH4 and BH4 alone. The generation of superoxide in the ischemic-reperfused myocardium was reduced in pigs treated with intracoronary L-arginine+BH4 versus the vehicle group (P<0.05). CONCLUSION: Administration of L-arginine+BH4 before reperfusion protects the heart from ischemia-reperfusion injury. The cardioprotective effect is mediated via NOS-dependent pathway resulting in diminished superoxide generation.
Assuntos
Arginina/administração & dosagem , Biopterinas/análogos & derivados , Cardiotônicos/administração & dosagem , Isquemia Miocárdica/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Animais , Biopterinas/administração & dosagem , Quimioterapia Combinada , Masculino , Isquemia Miocárdica/patologia , Traumatismo por Reperfusão Miocárdica/patologia , Ratos , Ratos Sprague-Dawley , Sus scrofa , SuínosRESUMO
The theory that red blood cells (RBCs) generate and release nitric oxide (NO)-like bioactivity has gained considerable interest. However, it remains unclear whether it can be produced by endothelial NO synthase (eNOS), which is present in RBCs, and whether NO can escape scavenging by hemoglobin. The aim of this study was to test the hypothesis that arginase reciprocally controls NO formation in RBCs by competition with eNOS for their common substrate arginine and that RBC-derived NO is functionally active following arginase blockade. We show that rodent and human RBCs contain functional arginase 1 and that pharmacological inhibition of arginase increases export of eNOS-derived nitrogen oxides from RBCs under basal conditions. The functional importance was tested in an ex vivo model of myocardial ischemia-reperfusion injury. Inhibitors of arginase significantly improved postischemic functional recovery in rat hearts if administered in whole blood or with RBCs in plasma. By contrast, arginase inhibition did not improve postischemic recovery when administered with buffer solution or plasma alone. The protective effect of arginase inhibition was lost in the presence of a NOS inhibitor. Moreover, hearts from eNOS(-/-) mice were protected when the arginase inhibitor was given with blood from wild-type donors. In contrast, when hearts from wild-type mice were given blood from eNOS(-/-) mice, the arginase inhibitor failed to protect against ischemia-reperfusion. These results strongly support the notion that RBCs contain functional eNOS and release NO-like bioactivity. This process is under tight control by arginase 1 and is of functional importance during ischemia-reperfusion.
Assuntos
Arginase/sangue , Eritrócitos/metabolismo , Óxido Nítrico Sintase Tipo III/sangue , Óxido Nítrico/sangue , Animais , Arginase/antagonistas & inibidores , Arginina/análogos & derivados , Arginina/farmacologia , Transporte Biológico Ativo , Cardiotônicos/farmacologia , Inibidores Enzimáticos/farmacologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Traumatismo por Reperfusão Miocárdica/sangue , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Nitratos/sangue , Óxido Nítrico Sintase Tipo III/deficiência , Óxido Nítrico Sintase Tipo III/genética , Nitritos/sangue , Ratos , Ratos WistarRESUMO
Reduced bioavailability of nitric oxide (NO) contributes to the development of myocardial ischemia-reperfusion (I/R) injury. Increased activity of arginase is a potential factor that reduces NO bioavailability by competing for the substrate L-arginine. The aim of the study was to test the hypothesis that inhibition of arginase after coronary artery occlusion protects from I/R injury and to explore possible mechanisms behind this effect. Male Sprague-Dawley rats subjected to 30 min of coronary artery ligation and 2h reperfusion were given i.v. before the reperfusion: 1) saline; 2) the arginase inhibitor N-omega-hydroxy-nor-L-arginine (nor-NOHA); 3) nor-NOHA with the NO synthase (NOS) inhibitor N(G)-monomethyl-L-arginine (L-NMMA); 4) nor-NOHA with the mitochondrial ATP-dependent K(+) (mitoKATP) channel blocker 5-hydroxydecanoic acid (5-HD); 5) nor-NOHA with the protein kinase C epsilon (PKCε) inhibitor ε-V1-2 or 6) ε-V1-2 alone. Infarct size in the control groups was 61±3% and it was reduced to 47±3% (P<0.01) by nor-NOHA. The cardioprotective effect was blocked by the NOS inhibitor L-NMMA. PKCε expression was reduced by I/R and this reduction was attenuated by nor-NOHA. Furthermore, the PKCε inhibitor ε-V1-2 abolished the protective effect of nor-NOHA (infarct size 69±6%). In addition, the cardioprotective effect of nor-NOHA was also abolished following blockade of the mitoKATP channel (infarct size 62±1%). Inhibition of arginase before reperfusion protects the heart from I/R injury via a NOS-dependent pathway, increased expression of PKCε and activation of mitoKATP channels.
Assuntos
Arginase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Óxido Nítrico/biossíntese , Canais de Potássio/metabolismo , Proteína Quinase C-épsilon/metabolismo , Animais , Arginase/metabolismo , Ativação Enzimática/efeitos dos fármacos , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Ativação do Canal Iônico/efeitos dos fármacos , Masculino , Infarto do Miocárdio/complicações , Infarto do Miocárdio/fisiopatologia , Ratos , Ratos Sprague-Dawley , Traumatismo por Reperfusão/complicações , Traumatismo por Reperfusão/prevenção & controleRESUMO
Consumption of L-arginine contributes to reduced bioavailability of nitric oxide (NO) that is critical for the development of ischemia-reperfusion injury. The aim of the study was to determine myocardial arginase expression and activity in ischemic-reperfusion myocardium and whether local inhibition of arginase within the ischemic myocardium results in increased NO production and protection against myocardial ischemia-reperfusion. Anesthetized pigs were subjected to coronary artery occlusion for 40 min followed by 4 h reperfusion. The pigs were randomized to intracoronary infusion of vehicle (n = 7), the arginase inhibitor N-hydroxy-nor-L-arginine (nor-NOHA, 2 mg/min, n = 7), the combination of nor-NOHA and the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA, 0.35 mg/min, n = 6) into the jeopardized myocardial area or systemic intravenous infusion of nor-NOHA (2 mg/min, n = 5) at the end of ischemia and start of reperfusion. The infarct size of the vehicle group was 80 ± 4% of the area at risk. Intracoronary nor-NOHA reduced infarct size to 46 ± 5% (P<0.01). Co-administration of L-NMMA abrogated the cardioprotective effect mediated by nor-NOHA (infarct size 72 ± 6%). Intravenous nor-NOHA did not reduce infarct size. Arginase I and II were expressed in cardiomyocytes, endothelial, smooth muscle and poylmorphonuclear cells. There was no difference in cytosolic arginase I or mitochondrial arginase II expression between ischemic-reperfused and non-ischemic myocardium. Arginase activity increased 2-fold in the ischemic-reperfused myocardium in comparison with non-ischemic myocardium. In conclusion, ischemia-reperfusion increases arginase activity without affecting cytosolic arginase I or mitochondrial arginase II expression. Local arginase inhibition during early reperfusion reduces infarct size via a mechanism that is dependent on increased bioavailability of NO.
Assuntos
Arginase/antagonistas & inibidores , Cardiotônicos/farmacologia , Inibidores Enzimáticos/farmacologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Óxido Nítrico/biossíntese , Animais , Western Blotting , Feminino , Miocárdio/enzimologia , SuínosRESUMO
Hypoxia and hypoxia/reoxygenation (H/R) are components of tissue ischemia and reperfusion implicated in myocardial infarction, organ transplantation, and tumor perfusion. H/R enhances production of reactive oxygen species (ROS). Candidate molecular targets of ROS are the catalytic site cysteine of protein tyrosine phosphatases (PTPs), which are major regulators of tyrosine kinase signaling. This study aimed at analyzing potential effects of H/R on PTP-oxidation in cultured cells and in heart tissue. Exposure of mouse NIH3T3 fibroblasts to H/R increased the oxidation of the PTPs SHP-2- and DEP-1. The catalytic pan-PTP- and SHP-2-activity after H/R were also decreased in rat cardiomyoblasts. In vivo dephosphorylation of the Platelet-derived Growth Factor (PDGF)-receptor in NIH3T3 fibroblasts was delayed following H/R. Erk1/2 displayed an antioxidant-sensitive increase in H/R. Furthermore, increased PDGF-induced cytoskeleton re-arrangements were evident following H/R and could be prevented by antioxidant pretreatment. Finally, decreased pan-PTP- and SHP-2 activity was demonstrated in tissue extracts from an ex vivo Langendorff-model of rat heart ischemia-reperfusion. This study thus demonstrates PTP-oxidation as a previously unrecognized molecular component of the cellular response to H/R in cells and tissues. The study additionally provides the first demonstration of increased PTP-oxidation in tissues under patho-physiological settings.
Assuntos
Proteínas Tirosina Fosfatases/metabolismo , Animais , Hipóxia Celular , Linhagem Celular , Camundongos , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Miócitos Cardíacos/metabolismo , Oxirredução , Oxigênio/metabolismo , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Ratos , Proteínas Tirosina Fosfatases Classe 3 Semelhantes a Receptores/metabolismo , Receptores do Fator de Crescimento Derivado de Plaquetas/metabolismoRESUMO
Eribis peptide 94 (EP 94) is a novel enkephalin analog, thought to interact with the µ- and δ-opioid receptors. The purpose of the present study was to examine the cardioprotective potential of EP 94 in two clinically relevant porcine models of myocardial ischaemia and reperfusion, and to investigate if such an effect is associated with an increased expression of endothelial nitric oxide synthase (eNOS). Forty-one anesthetized pigs underwent 40min of coronary occlusion followed by 4h of reperfusion. In Protocol I, balloon occlusion of the left anterior descending artery was performed with concurrent intravenous administration of (A) vehicle (n=7), (B) EP 94 (1ug/kg) after 5, 12, 19 and 26min of ischaemia (n=4) or (C) EP 94 (1ug/kg) after 26, 33, 40min of ischaemia (n=6). In Protocol II, open-chest pigs were administered (D) vehicle (n=6) or (E) 0.2ug/kg/min of EP 94 (n=6) through an intracoronary infusion into the jeopardized myocardium, started after 30min of ischaemia and maintained for 15min. The hearts were stained and the protein content of eNOS measured. EP 94 reduces infarct size when administered both early and late during ischaemia compared with vehicle (infarct size group A 61.6±2%, group B 50.2±3% and group C 49.2±2%, respectively, P<0.05), as well as when infused intracoronary (infarct size group D 82.2±3.9% and group E 61.2±2.5% respectively, P<0.01). Phosphorylated eNOS Ser(1177) in relation to total eNOS was significantly increased in the group administered EP 94, indicating activation of nitric oxide production.
Assuntos
Encefalinas/farmacologia , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/tratamento farmacológico , Traumatismo por Reperfusão Miocárdica/patologia , Peptídeos Opioides/farmacologia , Receptores Opioides/agonistas , Animais , Cardiotônicos/administração & dosagem , Cardiotônicos/farmacologia , Cardiotônicos/uso terapêutico , Modelos Animais de Doenças , Encefalinas/administração & dosagem , Encefalinas/uso terapêutico , Feminino , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/enzimologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Óxido Nítrico Sintase Tipo III/metabolismo , Peptídeos Opioides/administração & dosagem , Peptídeos Opioides/uso terapêutico , SuínosRESUMO
CONTEXT: Expression of the vasoconstrictor and proinflammatory peptide endothelin (ET)-1 is increased in insulin-resistant (IR) subjects. OBJECTIVE: The aim of this study was to investigate whether ET-1 regulates skeletal muscle glucose uptake in IR subjects in vivo and in cultured human skeletal muscle cells. DESIGN AND PARTICIPANTS: Eleven subjects participated in three protocols using brachial artery infusion of: A) BQ123 (10 nmol/min) and BQ788 (10 nmol/min) (ET(A) and ET(B) receptor antagonist, respectively), followed by coinfusion with insulin (0.05 mU/kg/min); B) insulin alone; and C) insulin followed by coinfusion with ET-1 (20 pmol/min). MAIN OUTCOME MEASURES: Forearm blood flow (FBF) and forearm glucose uptake (FGU) were determined. Glucose uptake and molecular signaling were determined in cultured skeletal muscle cells. RESULTS: ET(A)/ET(B) receptor blockade increased FGU by 63% (P < 0.05). Coadministration of insulin caused a further 2-fold increase in FGU (P < 0.001). ET(A)/ET(B) receptor blockade combined with insulin resulted in greater FGU than insulin infusion alone (P < 0.005). ET(A)/ET(B) receptor blockade increased FBF by 30% (P < 0.05), with a further 16% increase (P < 0.01) during insulin coinfusion. ET-1 decreased basal FBF by 35% without affecting FGU. ET-1 impaired basal and insulin-stimulated glucose uptake in cultured muscle cells (P < 0.01) via an effect that was prevented by ET(A)/ET(B) receptor blockade. CONCLUSION: ET(A)/ET(B) receptor blockade enhances basal and insulin-stimulated glucose uptake in IR subjects. ET-1 directly impairs glucose uptake in skeletal muscle cells via a receptor-dependent mechanism. These data suggest that ET-1 regulates glucose metabolism via receptor-dependent mechanisms in IR subjects.
Assuntos
Endotelina-1/fisiologia , Glucose/metabolismo , Resistência à Insulina/fisiologia , Músculo Esquelético/metabolismo , Transporte Biológico , Glicemia/análise , Índice de Massa Corporal , Artéria Braquial , Proteína C-Reativa/metabolismo , Endotelina-1/administração & dosagem , Endotelina-1/farmacologia , Antebraço/irrigação sanguínea , Hemoglobinas Glicadas/análise , Humanos , Hipertensão/metabolismo , Infusões Intra-Arteriais , Insulina/administração & dosagem , Insulina/sangue , Insulina/farmacologia , Masculino , Pessoa de Meia-Idade , Oligopeptídeos/administração & dosagem , Oligopeptídeos/farmacologia , Peptídeos Cíclicos/administração & dosagem , Peptídeos Cíclicos/farmacologia , Piperidinas/administração & dosagem , Piperidinas/farmacologia , Fluxo Sanguíneo Regional , Triglicerídeos/sangueRESUMO
AIMS: Nitric oxide (NO) is vital for the integrity of the cardiovascular system and protection against ischaemic heart disease. Arginase is up-regulated during ischaemia-reperfusion (IR) and this enzyme might compete with NO synthase (NOS) for arginine. The present study investigated whether arginase blockade protects from myocardial IR injury and whether such an effect is coupled to increased NO bioavailability. METHODS AND RESULTS: Sprague-Dawley rats were subjected to 30 min of coronary artery ligation, followed by 2 h of reperfusion. The animals were given either saline, or the arginase inhibitor N-omega-hydroxy-nor-l-arginine (nor-NOHA) with or without the NO scavenger carboxy-2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (cPTIO) or the NOS inhibitor N(G)-monomethyl-l-arginine (l-NMMA) iv 15 min before ischaemia. The infarct size was 79 +/- 4% of the area at risk in the control group. Nor-NOHA treatment reduced the infarct size to 39 +/- 7% (P < 0.001). Administration of cPTIO or l-NMMA completely abolished the protective effect of nor-NOHA. Expression of arginase I was significantly (P < 0.05) increased in ischaemic myocardium. Nor-NOHA treatment resulted in higher plasma levels of nitrite (P < 0.05) and a 10-fold increase in the citrulline/ornithine ratio (P < 0.001), indicating a shift in arginine utilization towards NOS. CONCLUSION: Inhibition of arginase protects from myocardial infarction by a mechanism that is dependent on NOS activity and bioavailability of NO by shifting arginine utilization from arginase towards NOS. These findings suggest that targeting of arginase is a promising future therapeutic strategy for protection against myocardial IR injury.
Assuntos
Arginase/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Óxido Nítrico/metabolismo , Aminoácidos/análise , Aminoácidos/sangue , Animais , Arginina/análogos & derivados , Arginina/farmacologia , Pressão Sanguínea , Frequência Cardíaca , Masculino , Infarto do Miocárdio/tratamento farmacológico , Miocárdio/metabolismo , Óxido Nítrico Sintase/fisiologia , Nitritos/sangue , Ratos , Ratos Sprague-DawleyRESUMO
AIMS: Cardiovascular disease and type 2 diabetes mellitus are associated with low plasma concentration of adiponectin. The aim of this study was to investigate whether adiponectin exerts cardioprotective effects during myocardial ischaemia-reperfusion and whether this effect is related to the production of nitric oxide (NO). METHODS AND RESULTS: Isolated rat hearts were subjected to 30 min of either global or local ischaemia followed by 60 min of reperfusion. The hearts received vehicle, adiponectin (3 microg/mL), the NO-synthase inhibitor nitro-l-arginine (L-NNA) (0.1 mM), or a combination of adiponectin and L-NNA at the onset of ischaemia. Haemodynamics, infarct size, and expression of endothelial NO-synthase (eNOS), AMP-activated protein kinase (AMPK), and Akt were determined. Adiponectin significantly increased left ventricular function and coronary flow during reperfusion in comparison with the vehicle group. Co-administration of L-NNA abrogated the improvement in myocardial function induced by adiponectin. Infarct size following local ischaemia-reperfusion was 40 +/- 6% of the area at risk in the vehicle group. Adiponectin reduced infarct size to 19 +/- 2% (P < 0.01). L-NNA did not affect infarct size per se but abolished the protective effect of adiponectin (infarct size 40 +/- 5%). Phosphorylation of eNOS Ser1177, AMPK Thr172, and Akt Ser 473 was increased in the adiponectin group (P < 0.05). CONCLUSION: Adiponectin protects from myocardial contractile dysfunction and limits infarct size following ischaemia and reperfusion by a mechanism involving activation of AMPK and production of NO.