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2.
Cell Stem Cell ; 24(4): 579-591.e12, 2019 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-30853557

RESUMO

Heart disease is a paramount cause of global death and disability. Although cardiomyocyte death plays a causal role and its suppression would be logical, no clinical counter-measures target the responsible intracellular pathways. Therapeutic progress has been hampered by lack of preclinical human validation. Mitogen-activated protein kinase kinase kinase kinase-4 (MAP4K4) is activated in failing human hearts and relevant rodent models. Using human induced-pluripotent-stem-cell-derived cardiomyocytes (hiPSC-CMs) and MAP4K4 gene silencing, we demonstrate that death induced by oxidative stress requires MAP4K4. Consequently, we devised a small-molecule inhibitor, DMX-5804, that rescues cell survival, mitochondrial function, and calcium cycling in hiPSC-CMs. As proof of principle that drug discovery in hiPSC-CMs may predict efficacy in vivo, DMX-5804 reduces ischemia-reperfusion injury in mice by more than 50%. We implicate MAP4K4 as a well-posed target toward suppressing human cardiac cell death and highlight the utility of hiPSC-CMs in drug discovery to enhance cardiomyocyte survival.


Assuntos
Doxorrubicina/farmacologia , Infarto/tratamento farmacológico , Infarto/patologia , Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Animais , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Relação Dose-Resposta a Droga , Feminino , Humanos , Peróxido de Hidrogênio/farmacologia , Células-Tronco Pluripotentes Induzidas/citologia , Infarto/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miócitos Cardíacos/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Relação Estrutura-Atividade
3.
Am J Physiol Heart Circ Physiol ; 301(2): H269-78, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21572013

RESUMO

With the growth of genetic engineering, mice have become increasingly common as models of human diseases, and this has stimulated the development of techniques to assess the murine cardiovascular system. Our group has developed nonimaging and dedicated Doppler techniques for measuring blood velocity in the large and small peripheral arteries of anesthetized mice. We translated technology originally designed for human vessels for use in smaller mouse vessels at higher heart rates by using higher ultrasonic frequencies, smaller transducers, and higher-speed signal processing. With these methods one can measure cardiac filling and ejection velocities, velocity pulse arrival times for determining pulse wave velocity, peripheral blood velocity and vessel wall motion waveforms, jet velocities for the calculation of the pressure drop across stenoses, and left main coronary velocity for the estimation of coronary flow reserve. These noninvasive methods are convenient and easy to apply, but care must be taken in interpreting measurements due to Doppler sample volume size and angle of incidence. Doppler methods have been used to characterize and evaluate numerous cardiovascular phenotypes in mice and have been particularly useful in evaluating the cardiac and vascular remodeling that occur following transverse aortic constriction. Although duplex ultrasonic echo-Doppler instruments are being applied to mice, dedicated Doppler systems are more suitable for some applications. The magnitudes and waveforms of blood velocities from both cardiac and peripheral sites are similar in mice and humans, such that much of what is learned using Doppler technology in mice may be translated back to humans.


Assuntos
Artérias/diagnóstico por imagem , Doenças Cardiovasculares/diagnóstico por imagem , Hemodinâmica , Fluxometria por Laser-Doppler , Ultrassonografia Doppler , Animais , Artérias/fisiopatologia , Velocidade do Fluxo Sanguíneo , Doenças Cardiovasculares/fisiopatologia , Modelos Animais de Doenças , Desenho de Equipamento , Fluxometria por Laser-Doppler/instrumentação , Camundongos , Miniaturização , Modelos Cardiovasculares , Fluxo Pulsátil , Fluxo Sanguíneo Regional , Transdutores de Pressão , Ultrassonografia Doppler/instrumentação
4.
Conf Proc IEEE Eng Med Biol Soc ; 2010: 3780-3, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-21096875

RESUMO

Mice are now commonly used as models of human cardiovascular diseases and conditions, but it is challenging to measure blood flow velocity in small vessels such as coronary arteries. Accordingly, we have developed a method using a 2 mm diameter 20 MHz pulsed Doppler probe applied to the chest of an anesthetized mouse to measure left main coronary blood flow velocity noninvasively. We also found that coronary flow velocity could be increased from baseline (B) to hyperemic (H) levels by changing the concentration of isoflurane gas anesthesia from 1% to 2.5% in oxygen and that the H levels are similar to or higher than those induced by adenosine. We used the ratio H/B to estimate coronary flow reserve (CFR) in young, adult, and old mice and in mice with atherosclerosis, coronary occlusion, pressure overload, and angiotensin infusion. We found that H/B increases with age from 2.4 (young) to 3.6 (old) and is reduced by all forms of coronary and vascular disease to as low as 1.1 by pressure overload. We conclude that CFR can be measured noninvasively and serially in mice as their cardiovascular systems adapt and remodel to various imposed or natural conditions, and that left main coronary flow reserve may be a good index of global cardiac function.


Assuntos
Fatores Etários , Aterosclerose/fisiopatologia , Vasos Coronários/fisiologia , Animais , Camundongos , Fluxo Sanguíneo Regional
5.
Circ Res ; 106(3): 546-50, 2010 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-20007913

RESUMO

RATIONALE: Cardiovascular physiology and pathophysiology vary dramatically over the course of the day. For example, myocardial infarction onset occurs with greater incidence during the early morning hours in humans. However, whether myocardial infarction tolerance exhibits a time-of-day dependence is unknown. OBJECTIVE: To investigate whether time of day of an ischemic insult influences clinically relevant outcomes in mice. METHODS AND RESULTS: Wild-type mice were subjected to ischemia/reperfusion (I/R) (45 minutes of ischemia followed by 1 day or 1 month of reperfusion) at distinct times of the day, using the closed-chest left anterior descending coronary artery occlusion model. Following 1 day of reperfusion, hearts subjected to ischemia at the sleep-to-wake transition (zeitgeber time [ZT]12) resulted in 3.5-fold increases in infarct size compared to hearts subjected to ischemia at the wake-to-sleep transition (ZT0). Following 1 month of reperfusion, prior ischemic event at ZT12 versus ZT0 resulted in significantly greater infarct volume, fibrosis, and adverse remodeling, as well as greater depression of contractile function. Genetic ablation of the cardiomyocyte circadian clock (termed cardiomyocyte-specific circadian clock mutant [CCM] mice) attenuated/abolished time-of-day variations in I/R outcomes observed in wild-type hearts. Investigation of Akt and glycogen synthase kinase-3beta in wild-type and CCM hearts identified these kinases as potential mechanistic ties between the cardiomyocyte circadian clock and I/R tolerance. CONCLUSIONS: We expose a profound time-of-day dependence for I/R tolerance, which is mediated by the cardiomyocyte circadian clock. Further understanding of I/R tolerance rhythms will potentially provide novel insight regarding the etiology and treatment of ischemia-induced cardiac dysfunction.


Assuntos
Ritmo Circadiano/fisiologia , Quinase 3 da Glicogênio Sintase/fisiologia , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Miócitos Cardíacos/fisiologia , Fatores de Transcrição ARNTL/biossíntese , Fatores de Transcrição ARNTL/genética , Animais , Fatores de Transcrição de Zíper de Leucina Básica/biossíntese , Fatores de Transcrição de Zíper de Leucina Básica/genética , Ritmo Circadiano/genética , Proteínas de Ligação a DNA/biossíntese , Proteínas de Ligação a DNA/genética , Regulação da Expressão Gênica/fisiologia , Quinase 3 da Glicogênio Sintase/genética , Glicogênio Sintase Quinase 3 beta , Masculino , Camundongos , Camundongos Mutantes , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/enzimologia , Traumatismo por Reperfusão Miocárdica/patologia , Miócitos Cardíacos/enzimologia , Fosforilação , Fosfosserina/análise , Processamento de Proteína Pós-Traducional , Recuperação de Função Fisiológica , Sono/fisiologia , Fatores de Tempo , Fatores de Transcrição/biossíntese , Fatores de Transcrição/genética , Vigília/fisiologia
6.
Conf Proc IEEE Eng Med Biol Soc ; 2009: 1094-7, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19963485

RESUMO

Mice are now commonly used as models of human cardiovascular diseases and conditions, but it is challenging to measure blood flow velocity in small vessels such as coronary arteries. Accordingly, we have developed a method using a 2 mm diameter 20 MHz pulsed Doppler probe applied to the chest of anesthetized mice to measure left main coronary blood flow velocity noninvasively. We also found that coronary flow velocity could be increased from baseline (B) to hyperemic (H) levels by changing the concentration of isoflurane gas anesthesia from 1% to 2.5% in oxygen. We used the ratio B/H to estimate coronary flow reserve (CFR) in young, adult, and old mice and in mice with obesity, atherosclerosis, pressure overload hypertrophy, and coronary artery occlusion. We found that B/H increases with age from 2.4 (young) to 3.6 (old) and is decreased to as low as 1.1 by all forms of heart and vascular disease studied. We conclude that CFR can be measured noninvasively and serially in mice as their cardiovascular systems adapt and remodel to various imposed or natural conditions, and that coronary flow reserve may be a good index of overall cardiac function in mice and potentially in man.


Assuntos
Anormalidades Cardiovasculares/fisiopatologia , Circulação Coronária/fisiologia , Envelhecimento/fisiologia , Animais , Apolipoproteínas E/deficiência , Apolipoproteínas E/genética , Engenharia Biomédica , Velocidade do Fluxo Sanguíneo/fisiologia , Anormalidades Cardiovasculares/diagnóstico por imagem , Doença da Artéria Coronariana/diagnóstico por imagem , Doença da Artéria Coronariana/fisiopatologia , Estenose Coronária/diagnóstico por imagem , Estenose Coronária/fisiopatologia , Vasos Coronários/diagnóstico por imagem , Vasos Coronários/fisiopatologia , Modelos Animais de Doenças , Eletrocardiografia , Testes de Função Cardíaca/métodos , Humanos , Camundongos , Camundongos Knockout , Ultrassonografia Doppler
7.
Ultrasound Med Biol ; 34(6): 892-901, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18255218

RESUMO

Aortic banding produces pressure overload cardiac hypertrophy in mice, leading to decompensated heart failure in four to eight weeks, but the effects on coronary blood flow velocity and reserve are unknown. To determine whether coronary flow reserve (CFR) was reduced, we used noninvasive 20-MHz Doppler ultrasound to measure left main coronary flow velocity at baseline (B) and at hyperemia (H) induced by low (1%) and high (2.5%) concentrations of isoflurane gas anesthesia. Ten mice were studied before (Pre) and at 1 d, 7 d, 14 d and 21 d after constricting the aortic arch to 0.4 mm diameter distal to the innominate artery. We also measured cardiac inflow and outflow velocities at the mitral and aortic valves and velocity at the jet distal to the aortic constriction. The pressure drop as estimated by 4V2 at the jet was 51 +/- 5.1 (mean +/- SE) mm Hg at 1 d, increasing progressively to 74 +/- 5.2 mm Hg at 21 d. Aortic and mitral blood velocities were not significantly different after banding (p = NS), but CFR, as estimated by H/B, dropped progressively from 3.2 +/- 0.3 before banding to 2.2 +/- 0.4, 1.7 +/- 0.3, 1.4 +/- 0.2 and 1.1 +/- 0.1 at 1 d, 7 d, 14 d and 21 d, respectively (all p < 0.01 vs. Pre). There was also a significant and progressive increase the systolic/diastolic velocity ratio (0.17 Pre to 0.92 at 21 d, all p < 0.01 vs. Pre) suggesting a redistribution of perfusion from subendocardium to subepicardium. We show for the first time that CFR, as estimated by the hyperemic response to isoflurane and measured by Doppler ultrasound, can be measured serially in mice and conclude that CFR is virtually eliminated in banded mice after 21 d of remodeling and hypertrophy. These results demonstrate that CFR is reduced in mice as in humans with cardiac disease but before the onset of decompensated heart failure.


Assuntos
Cardiomegalia/diagnóstico por imagem , Vasos Coronários/diagnóstico por imagem , Ultrassonografia Doppler/métodos , Anestésicos , Animais , Valva Aórtica/diagnóstico por imagem , Velocidade do Fluxo Sanguíneo , Cardiomegalia/fisiopatologia , Vasos Coronários/fisiopatologia , Hiperemia/diagnóstico por imagem , Hiperemia/fisiopatologia , Isoflurano , Camundongos , Camundongos Endogâmicos C57BL , Valva Mitral/diagnóstico por imagem , Modelos Animais , Fluxo Sanguíneo Regional , Disfunção Ventricular Esquerda/diagnóstico por imagem , Disfunção Ventricular Esquerda/fisiopatologia
8.
Ultrasound Med Biol ; 33(4): 512-21, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17346873

RESUMO

The commonly used anesthetic agent isoflurane (ISO) is a potent coronary vasodilator that could potentially be used in the assessment of coronary reserve, but its effects on coronary blood flow in mice are unknown. Coronary reserve is reduced by age, coronary artery disease and other cardiac pathologies in man, and some of these conditions can now be modeled in mice. Accordingly, we used Doppler ultrasound to measure coronary flow velocity in mice anesthetized with low (1%) and high (2.5%) levels of ISO to generate baseline (B) and elevated hyperemic (H) coronary flows, respectively. A 20-MHz Doppler probe was mounted in a micromanipulator and pointed trans-thoracically toward the origin of the left main coronary arteries of 10 6-wk (Young [Y]), 10 2-y (Old [O]) and 20 2-y apolipoprotein-E null (ApoE(-/-)) atherosclerotic (A) mice. In each mouse, we measured (B) and (H) peak diastolic velocities. B was 35.4 +/- 1.4 cm/s (Y), 24.8 +/- 1.6 (O) and 51.7 +/- 6.4 (A); H was 83.5 +/- 1.3 (Y), 86.5 +/- 1.9 (O) and 120 +/- 16.9 (A) and H/B was 2.4 +/- 0.1 (Y), 3.6 +/- 0.2 (O) and 2.5 +/- 0.2 (A). The differences in baseline velocities and H/B between O and Y and between A and O were significant (p < 0.01), whereas the differences in hyperemic velocities were not (p > 0.05). H/B was higher in old mice as a result of decreased baseline flow rather than increased hyperemic flow velocity. In contrast, ApoE(-/-) mice have increased baseline and hyperemic velocities, perhaps because of coronary lesions. The differences in baseline velocities between young and old mice could be the result of age-related changes in basal metabolism or to differential sensitivity to isoflurane. We conclude that Doppler ultrasound combined with coronary vasodilation via isoflurane could provide a convenient and noninvasive method to estimate coronary reserve in mice, but also that care must be taken when assessing coronary flow in mice under isoflurane anesthesia because of its potent coronary vasodilator properties.


Assuntos
Envelhecimento , Apolipoproteínas E/genética , Circulação Coronária/efeitos dos fármacos , Isoflurano/farmacologia , Vasodilatadores/farmacologia , Animais , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Vasos Coronários/efeitos dos fármacos , Vasos Coronários/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Ultrassonografia Doppler/instrumentação , Ultrassonografia Doppler/métodos
9.
J Gerontol A Biol Sci Med Sci ; 62(12): 1319-25, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18166681

RESUMO

We studied cardiac function in young and old, wild-type (WT), and longer-living Little mice using cardiac flow velocities, echocardiographic measurements, and left ventricular (LV) pressure (P) to determine if enhanced reserves were in part responsible for longevity in these mice. Resting/baseline cardiac function, as measured by velocities, LV dimensions, +dP/dt(max), and -dP/dt(max), was significantly lower in young Little mice versus young WT mice. Fractional shortening (FS) increased significantly, and neither +dP/dt(max) nor -dP/dt(max) declined with age in Little mice. In contrast, old WT mice had no change in FS but had significantly lower +dP/dt(max) and -dP/dt(max) versus young WT mice. Significant decreases were observed in the velocity indices of old Little mice versus old WT mice, but other parameters were unchanged. The magnitude of dobutamine stress response remained unchanged with age in Little mice, while that in WT mice decreased. These data suggest that while resting cardiac function in Little mice versus WT mice is lower at young age, it is relatively unaltered with aging. Additionally, cardiac function in response to stress was maintained with age in Little mice but not in their WT counterparts. Thus, some mouse models of increased longevity may not be associated with enhanced reserves.


Assuntos
Envelhecimento/fisiologia , Coração/fisiologia , Camundongos/fisiologia , Animais , Peso Corporal , Nanismo/fisiopatologia , Ecocardiografia , Teste de Esforço , Fator de Crescimento Insulin-Like I/análise
10.
J Mol Cell Cardiol ; 41(1): 62-7, 2006 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-16781728

RESUMO

Myocardial ischemia-reperfusion injury represents a combination of factors, namely the intrinsic cellular response to ischemia and the extrinsic acute inflammatory response. Recent studies in mesenteric and skeletal muscle reperfusion models identified natural IgM as a major initiator of pathology through the activation of the complement system and inflammatory cells. To determine whether a similar mechanism is involved in myocardial tissues, mice bearing an altered natural IgM repertoire (Cr2-/-) were examined in a murine model of coronary artery ischemia. Notably, these mice were significantly protected based on the reduced infarct size, limited apoptosis of cardiomyocytes, and decreased neutrophil infiltration. Protection was IgM-dependent as reconstitution of these mice with wild-type IgM restored myocardial reperfusion injury. These results support a model in which natural IgM initiates the acute inflammatory response in the myocardium following ischemia and reperfusion.


Assuntos
Imunoglobulina M/fisiologia , Isquemia Miocárdica/imunologia , Traumatismo por Reperfusão Miocárdica/imunologia , Traumatismo por Reperfusão Miocárdica/patologia , Animais , Apoptose , Modelos Animais de Doenças , Proteínas de Homeodomínio/genética , Proteínas de Homeodomínio/metabolismo , Camundongos , Camundongos Mutantes , Necrose , Neutrófilos/patologia , Receptores de Complemento/genética
11.
FASEB J ; 20(7): 916-25, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16675849

RESUMO

Ventricular myocyte hypertrophy is an important compensatory growth response to pressure overload. However, pathophysiological cardiac hypertrophy is accompanied by reactive fibrosis and remodeling. The Rho kinase family, consisting of ROCK1 and ROCK2, has been implicated in cardiac hypertrophy and ventricular remodeling. However, these previous studies relied heavily on pharmacological inhibitors,and not on gene deletion. Here we used ROCK1knockout (ROCK1-/-) mice to investigate role of ROCK1 in the development of ventricular remodeling induced by transverse aortic banding. We observed that ROCK1 deletion did not impair compensatory hypertrophic response induced by pressure overload. However, ROCK1-/- mice exhibited reduced perivascular and interstitial fibrosis, which was observed at 3 wk but not at 1 wk after the banding. The reduced fibrosis in the myocardium of ROCK1-/- mice was closely associated with reduced expression of a variety of extracellular matrix (ECM) proteins and fibrogenic cytokines such as TGFbeta2 and connective tissue growth factor. This inhibitory effect of ROCK1 deletion on pathophysiological induction of fibrogenic cytokines was further confirmed in the myocardium of transgenic mice with cardiomyocyte-specific overexpression of Gq. Thus, these results indicate that ROCK1 contributes to the development of cardiac fibrosis and induction of fibrogenic cytokines in cardiomyocytes in response to pathological stimuli.


Assuntos
Cardiomegalia/metabolismo , Fibrose/metabolismo , Fibrose/prevenção & controle , Coração/fisiopatologia , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/metabolismo , Animais , Cardiomegalia/genética , Cardiomegalia/patologia , Cardiomegalia/fisiopatologia , Fibrose/patologia , Regulação Enzimológica da Expressão Gênica , Genótipo , Coração/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Camundongos Knockout , Fenótipo , Pressão , Proteínas Serina-Treonina Quinases/genética , Remodelação Ventricular/fisiologia , Quinases Associadas a rho
12.
Am J Physiol Heart Circ Physiol ; 291(5): H2504-14, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16731644

RESUMO

Epidemiological studies indicate that obesity, insulin resistance, and diabetes are important comorbidities of patients with ischemic heart disease and increase mortality and development of congestive heart failure after myocardial infarction. Although ob/ob and db/db mice are commonly used to study obesity with insulin resistance or diabetes, mutations in the leptin gene or its receptor are rarely the cause of obesity in humans, which is, instead, primarily a consequence of dietary and lifestyle factors. Therefore, we used a murine model of diet-induced obesity to examine the physiological effects of obesity and the inflammatory and healing response of diet-induced obese (DIO) mice after myocardial ischemia-reperfusion injury. DIO mice developed hyperinsulinemia and insulin resistance and hepatic steatosis, with significant ectopic lipid deposition in the heart and cardiac hypertrophy in the absence of significant changes in blood pressure. The mRNA levels of chemokines at 24 h and cytokines at 24 and 72 h of reperfusion were higher in DIO than in lean mice. In granulation tissue at 72 h of reperfusion, macrophage density was significantly increased, whereas neutrophil density was reduced, in DIO mice compared with lean mice. At 7 days of reperfusion, collagen deposition in the scar was significantly reduced and left ventricular (LV) dilation and cardiac hypertrophy were increased, indicative of adverse LV remodeling, in infarcted DIO mice. Characterization of a murine diet-induced model of obesity and insulin resistance that satisfies many aspects commonly observed in human obesity allows detailed examination of the adverse cardiovascular effects of diet-induced obesity at the molecular level.


Assuntos
Dieta/efeitos adversos , Inflamação/etiologia , Infarto do Miocárdio/complicações , Obesidade/fisiopatologia , Remodelação Ventricular , Animais , Feminino , Inflamação/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/etiologia , Infarto do Miocárdio/fisiopatologia , Traumatismo por Reperfusão Miocárdica/fisiopatologia , Obesidade/etiologia
13.
IEEE Trans Biomed Eng ; 52(10): 1771-83, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16235663

RESUMO

We have developed a high-frequency, high-resolution Doppler spectrum analyzer (DSPW) and compared its performance against an adapted clinical Medasonics spectrum analyzer (MSA) and a zero-crossing interval histogram (ZCIH) used previously by us to evaluate cardiovascular physiology in mice. The aortic velocity (means +/- SE: 92.7 +/- 2.5 versus 82.2 +/- 1.8 cm/s) and aortic acceleration (8194 +/- 319 versus 5178 +/- 191 cm/s2) determined by the DSPW were significantly higher compared to those by the MSA. Aortic ejection time was shorter (48.3 +/- 0.9 versus 64.6 +/- 1.8 ms) and the isovolumic relaxation was longer (17.6 +/- 0.6 versus 13.5 +/- 0.6 ms) when determined by the DSPW because it generates shorter temporal widths in the velocity spectra when compared to the MSA. These data indicate that the performance of the DSPW in evaluating cardiovascular physiology was better than that of the MSA. There were no significant differences between the aortic pulse wave velocity determined by using the ZCIH (391 +/- 16 cm/s) and the DSPW (394 +/- 20 cm/s). Besides monitoring cardiac function, we have used the DSPW for studying peripheral vascular physiology in normal, transgenic, and surgical models of mice. Several applications such as the detection of high stenotic jet velocities (> 4 m/s), vortex shedding frequencies (250 Hz), and subtle changes in wave shapes in peripheral vessels which could not obtained with clinical Doppler systems are now made possible with the DSPW.


Assuntos
Estenose da Valva Aórtica/diagnóstico por imagem , Estenose da Valva Aórtica/fisiopatologia , Velocidade do Fluxo Sanguíneo , Ecocardiografia Doppler de Pulso/instrumentação , Hemorreologia/instrumentação , Interpretação de Imagem Assistida por Computador/instrumentação , Processamento de Sinais Assistido por Computador/instrumentação , Algoritmos , Animais , Inteligência Artificial , Ecocardiografia Doppler de Pulso/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Hemorreologia/métodos , Interpretação de Imagem Assistida por Computador/métodos , Camundongos
14.
Circulation ; 111(22): 2935-42, 2005 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-15927970

RESUMO

BACKGROUND: Matricellular proteins are extracellular matrix proteins that do not contribute directly to tissue integrity but are capable of modulating cell function. We hypothesized that the matricellular protein thrombospondin (TSP)-1, a potent inhibitor of angiogenesis and activator of transforming growth factor (TGF-beta), is induced in healing myocardial infarcts and plays a role in suppressing the postinfarction inflammatory response, inhibiting local angiogenesis, and limiting expansion of granulation tissue into the noninfarcted area. METHODS AND RESULTS: We used a canine and a murine model of reperfused infarction. TSP-1 mRNA was induced in canine infarcts after 1 hour of ischemia and 3 to 7 days of reperfusion. TSP-1 protein showed a strikingly selective localization in the extracellular matrix, microvascular endothelium, and a subset of mononuclear cells of the infarct border zone after 5 to 28 days of reperfusion. Isolated canine venous endothelial cells showed low-level constitutive expression of TSP-1 mRNA, which was markedly induced by TGF-beta, and basic fibroblast growth factor. Murine infarcts also had marked TSP-1 deposition in the border zone. Infarcted TSP-1-/- mice exhibited sustained upregulation of the chemokines monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, and interferon-gamma-inducible protein-10/CXCL10 and the cytokines interleukin-1beta, interleukin-6, and TGF-beta, suggesting an enhanced and prolonged postinfarction inflammatory response. In addition, TSP-1-/- mice had markedly increased macrophage and myofibroblast density in infarcts and in remodeling noninfarcted myocardial areas neighboring the myocardial scar, suggesting expansion of granulation tissue formation into the noninfarcted territory. TSP-1-/- animals had more extensive postinfarction remodeling than wild-type mice, although infarct size was similar in both groups. CONCLUSIONS: The infarct border zone may be capable of modulating the healing process through its unique extracellular matrix content. The selective endogenous expression of TSP-1 in the infarct border zone may serve as a "barrier," limiting expansion of granulation tissue and protecting the noninfarcted myocardium from fibrotic remodeling.


Assuntos
Infarto do Miocárdio/imunologia , Infarto do Miocárdio/patologia , Regeneração , Trombospondina 1/fisiologia , Animais , Quimiocinas/genética , Modelos Animais de Doenças , Cães , Endotélio Vascular/metabolismo , Proteínas da Matriz Extracelular/fisiologia , Regulação da Expressão Gênica , Inflamação , Camundongos , Camundongos Knockout , RNA Mensageiro/análise , Regeneração/imunologia , Traumatismo por Reperfusão , Trombospondina 1/análise , Trombospondina 1/genética , Regulação para Cima
15.
Circ Res ; 96(8): 881-9, 2005 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-15774854

RESUMO

The CC chemokine Monocyte Chemoattractant Protein (MCP)-1/CCL2 has potent mononuclear cell chemo-attractant properties, modulates fibroblast and endothelial cell phenotype and may play an important role in wound healing. In order to examine whether MCP-1 critically regulates myocardial infarct healing, we studied the effects of MCP-1 gene disruption and antibody neutralization in a closed-chest model of reperfused murine myocardial infarction. MCP-1-/- mice had decreased and delayed macrophage infiltration in the healing infarct and demonstrated delayed replacement of injured cardiomyocytes with granulation tissue. In contrast, the time course and density of neutrophil infiltration was similar in MCP-1 null and wild-type animals. MCP-1-/- infarcts had decreased mRNA expression of the cytokines TNF-alpha, IL-1beta, TGF-beta2, -beta3, and IL-10 and demonstrated defective macrophage differentiation evidenced by decreased Osteopontin-1 expression. MCP-1 deficiency diminished myofibroblast accumulation but did not significantly affect infarct angiogenesis. Despite showing delayed phagocytotic removal of dead cardiomyocytes, MCP-1-/- mice had attenuated left ventricular remodeling, but similar infarct size when compared with wild-type animals. MCP-1 antibody inhibition resulted in defects comparable with the pathological findings noted in infarcted MCP-1-/- animals without an effect on macrophage recruitment. MCP-1 has important effects on macrophage recruitment and activation, cytokine synthesis and myofibroblast accumulation in healing infarcts. Absence of MCP-1 results in attenuated post-infarction left ventricular remodeling, at the expense of a prolonged inflammatory phase and delayed replacement of injured cardiomyocytes with granulation tissue.


Assuntos
Quimiocina CCL2/fisiologia , Infarto do Miocárdio/fisiopatologia , Animais , Quimiocinas/genética , Citocinas/biossíntese , Feminino , Granuloma/patologia , Leucócitos/fisiologia , Macrófagos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Infarto do Miocárdio/patologia , Miócitos Cardíacos/patologia , Neovascularização Patológica/etiologia , Osteopontina , RNA Mensageiro/análise , Sialoglicoproteínas/análise , Remodelação Ventricular
16.
Am J Physiol Heart Circ Physiol ; 288(6): H2836-42, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15665051

RESUMO

Limitation of damage after ischemia and reperfusion injury to the myocardium remains an elusive clinical goal. Previous studies have suggested that molecular chaperones, which include members of the heat shock protein (Hsp) family, may have cardioprotective effects, although the protective role of endogenous chaperones has not been well documented. CHIP (carboxyl terminus of Hsp70-interacting protein) is a cochaperone/ubiquitin ligase that integrates the response to stress at multiple levels. We tested the response of CHIP(-/-) mice to in vivo ischemia and reperfusion injury induced by left anterior descending coronary artery ligation. Compared with wild-type littermates, CHIP(-/-) mice had decreased survival and increased incidence of arrhythmias during reperfusion. The size of myocardial infarction, as assessed by the ratio of infarct area to area at risk, was 50% greater in CHIP(-/-) mice. Increased infarct size was accompanied by impaired upregulation of the chaperone Hsp70 after ischemia-reperfusion injury. In situ analysis also indicated that hearts of CHIP(-/-) mice were more prone to develop apoptosis in cardiomyocytes and especially endothelial cells of intramural vessels. Previous studies have found that CHIP plays a central role in maintaining protein quality control and coordinating the response to stress. The present data indicate that these functions of CHIP provide a critical cardioprotective effect in the setting of ischemia-reperfusion injury due in part to increased apoptosis in cardiac cells. Quality control mechanisms therefore may be underappreciated clinical targets for maximizing myocardial protection after injury.


Assuntos
Cardiotônicos/farmacologia , Proteínas de Transporte/fisiologia , Proteínas de Choque Térmico HSP70/fisiologia , Infarto do Miocárdio/fisiopatologia , Ubiquitina-Proteína Ligases/fisiologia , Proteínas Adaptadoras de Transdução de Sinal , Animais , Arritmias Cardíacas/prevenção & controle , Proteínas de Transporte/genética , Ecocardiografia , Proteínas de Choque Térmico HSP70/deficiência , Proteínas de Choque Térmico HSP70/genética , Frequência Cardíaca/fisiologia , Camundongos , Camundongos Knockout , Isquemia Miocárdica/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Ubiquitina-Proteína Ligases/genética , Função Ventricular Esquerda/fisiologia
17.
J Pathol ; 205(1): 102-11, 2005 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-15586361

RESUMO

Mast cells and macrophages infiltrate healing myocardial infarcts and may play an important role in regulating fibrous tissue deposition and extracellular matrix remodelling. This study examined the time-course of macrophage and mast cell accumulation in healing infarcts and studied the histological characteristics and protease expression profile of mast cells in a canine model of experimental infarction. Although macrophages were more numerous than mast cells in infarct granulation tissue, macrophage density decreased during maturation of the scar, whereas mast cell numbers remained persistently elevated. During the inflammatory phase of infarction, newly recruited leucocytes infiltrated the injured myocardium and appeared to be clustered in close proximity to degranulating cardiac mast cells. During the proliferative phase of healing, mast cells had decreased granular content and were localized close to infarct neovessels. In contrast, macrophages showed no selective localization. Mast cells in healing canine infarcts were alcian blue/safranin-positive cells that expressed both tryptase and chymase. In order to explain the pro-inflammatory and angiogenic actions of tryptase--the major secretory protein of mast cells--its effects on endothelial chemokine expression were examined. Chemokines are chemotactic cytokines that play an important role in leucocyte trafficking and angiogenesis and are highly induced in infarcts. Tryptase, a proteinase-activated receptor (PAR)-2 agonist, induced endothelial expression of the angiogenic chemokines CCL2/MCP-1 and CXCL8/IL-8, but not the angiostatic chemokine CXCL10/IP-10. Endothelial PAR-2 stimulation with the agonist peptide SLIGKV induced a similar chemokine expression profile. Mast cell tryptase may exert its angiogenic effects in part through selective stimulation of angiogenic chemokines.


Assuntos
Endotélio Vascular/patologia , Mastócitos/enzimologia , Infarto do Miocárdio/patologia , Serina Endopeptidases/fisiologia , Animais , Degranulação Celular , Células Cultivadas , Quimiocinas/metabolismo , Circulação Coronária , Cães , Células Endoteliais/patologia , Feminino , Macrófagos/patologia , Masculino , Mastócitos/patologia , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/metabolismo , Reperfusão Miocárdica , Traumatismo por Reperfusão Miocárdica/enzimologia , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Neovascularização Patológica , Triptases , Cicatrização
18.
EMBO J ; 23(17): 3559-69, 2004 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-15297879

RESUMO

Hypertrophy allows the heart to adapt to workload but culminates in later pump failure; how it is achieved remains uncertain. Previously, we showed that hypertrophy is accompanied by activation of cyclin T/Cdk9, which phosphorylates the C-terminal domain of the large subunit of RNA polymerase II, stimulating transcription elongation and pre-mRNA processing; Cdk9 activity was required for hypertrophy in culture, whereas heart-specific activation of Cdk9 by cyclin T1 provoked hypertrophy in mice. Here, we report that alphaMHC-cyclin T1 mice appear normal at baseline yet suffer fulminant apoptotic cardiomyopathy when challenged by mechanical stress or signaling by the G-protein Gq. At pathophysiological levels, Cdk9 activity suppresses many genes for mitochondrial proteins including master regulators of mitochondrial function (peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1), nuclear respiratory factor-1). In culture, cyclin T1/Cdk9 suppresses PGC-1, decreases mitochondrial membrane potential, and sensitizes cardiomyocytes to apoptosis, effects rescued by exogenous PGC-1. Cyclin T1/Cdk9 inhibits PGC-1 promoter activity and preinitiation complex assembly. Thus, chronic activation of Cdk9 causes not only cardiomyocyte enlargement but also defective mitochondrial function, via diminished PGC-1 transcription, and a resulting susceptibility to apoptotic cardiomyopathy.


Assuntos
Quinase 9 Dependente de Ciclina/metabolismo , Insuficiência Cardíaca/etiologia , Miocárdio/metabolismo , Fatores de Transcrição/metabolismo , Animais , Apoptose , Células Cultivadas , Ciclina T , Ciclinas/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Ativação Enzimática , Expressão Gênica , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/metabolismo , Humanos , Camundongos , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Fator 1 Relacionado a NF-E2 , Fator 1 Nuclear Respiratório , Fatores Nucleares Respiratórios , Regiões Promotoras Genéticas , RNA Polimerase II/metabolismo , Ratos , Transativadores/genética , Transativadores/metabolismo , Fatores de Transcrição/genética , Transcrição Genética
19.
Am J Physiol Heart Circ Physiol ; 287(3): H1426-32, 2004 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15317682

RESUMO

Despite the extensive use of genetically altered mice to study cardiovascular physiology and pathology, it remains difficult to quantify arterial function noninvasively in vivo. We have developed a noninvasive Doppler method for quantifying vessel wall motion in anesthetized mice. A 20-MHz probe was held by an alligator clip and positioned over the carotid arteries of 16 mice, including six 3- to 5-mo-old wild-type (WT), four 30-mo-old senescent (old), two apolipoprotein E null (ApoE), and four alpha-smooth muscle actin null (alpha-SMA) mice. Doppler signals were obtained simultaneously from both vessel walls and from blood flow. The calculated displacement signals from the near and far walls were subtracted to generate a diameter signal from which the excursion and an augmentation index were calculated. The excursion ranged between 13 microm (in ApoE) and 95 microm (in alpha-SMA). The augmentation index was lowest in the WT mice (0.06) and highest in the old mice (0.29). We conclude that Doppler signal processing may be used to measure vessel wall motion in mice with high spatial and temporal resolution and that diameter signals can replace pressure signals for calculating the augmentation index. This noninvasive method is able to identify and confirm characteristic changes in arterial properties previously associated with age, atherosclerosis, and the absence of vascular tone.


Assuntos
Artérias Carótidas/diagnóstico por imagem , Movimento (Física) , Actinas/deficiência , Envelhecimento , Animais , Apolipoproteínas E/deficiência , Velocidade do Fluxo Sanguíneo , Artérias Carótidas/fisiologia , Camundongos , Camundongos Knockout , Modelos Cardiovasculares , Músculo Liso/metabolismo , Ultrassonografia Doppler/instrumentação
20.
J Interv Card Electrophysiol ; 11(1): 5-14, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15273447

RESUMO

INTRODUCTION: The transgenic mouse is a popular model for human inherited cardiac disease. Electrophysiology (EP) studies have recently been performed in transgenic mice to characterize the electrical phenotype of the heart. However, little is known regarding the impact of experimental conditions or model selection on the outcome of EP studies in mice. METHODS AND RESULTS: We investigated the effects of experimental conditions on mouse cardiac EP by (1) comparing the findings of transesophageal pacing with those of invasive intracardiac pacing, (2) elucidating the effects of commonly used anesthetic agents, and (3) determining the impact of changes in body temperature. We also investigated the effects of model selection by (1) studying the dependence on mouse strain, and (2) exploring the effects of age. We found that EP parameters derived by both transesophageal and intracardiac pacing/recordings methods were similar. On the other hand, the anesthetic mixture of ketamine, xylazine, and acepromazine had profound effects on cardiac EP compared to sodium pentobarbital or isoflurane. Meanwhile, compared to normal body temperature (97-99 F), low body temperature (92-94 F) prolonged most cardiac EP parameters, while high body temperature (102-104 F) had little effect. Heart rate was a sensitive indicator of changes in body temperature. Significant differences were observed in specialized conduction system properties among the mouse strains studied (FVB, C57, and DBA). Furthermore, atrial electrical remodeling was evidently associated with age, while ventricular electrical properties were virtually unaltered. In comparison with corresponding invasive EP parameters, we found that the QT interval was not a reliable EP index in the mouse. CONCLUSIONS: Cardiac EP variability may result from differences in experimental techniques including anesthesia and body temperature and from differences in mouse selection including strain and age. The influence of these factors should be considered when characterizing the electrical phenotype of transgenic mice in cardiovascular research.


Assuntos
Envelhecimento/fisiologia , Anestésicos/farmacologia , Temperatura Corporal , Estimulação Cardíaca Artificial/métodos , Técnicas Eletrofisiológicas Cardíacas , Coração/fisiologia , Fatores Etários , Animais , Temperatura Corporal/efeitos dos fármacos , Temperatura Corporal/fisiologia , Estimulação Elétrica , Eletrocardiografia , Feminino , Coração/efeitos dos fármacos , Átrios do Coração , Sistema de Condução Cardíaco/fisiologia , Masculino , Camundongos , Camundongos Transgênicos , Fatores Sexuais , Função Ventricular
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