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1.
Am J Hum Genet ; 103(2): 276-287, 2018 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-30075114

RESUMO

Primary hypertension is a major risk factor for ischemic heart disease, stroke, and chronic kidney disease. Insights obtained from the study of rare Mendelian forms of hypertension have been invaluable in elucidating the mechanisms causing primary hypertension and development of antihypertensive therapies. Endothelial cells play a key role in the regulation of blood pressure; however, a Mendelian form of hypertension that is primarily due to endothelial dysfunction has not yet been described. Here, we show that the urea cycle disorder, argininosuccinate lyase deficiency (ASLD), can manifest as a Mendelian form of endothelial-dependent hypertension. Using data from a human clinical study, a mouse model with endothelial-specific deletion of argininosuccinate lyase (Asl), and in vitro studies in human aortic endothelial cells and induced pluripotent stem cell-derived endothelial cells from individuals with ASLD, we show that loss of ASL in endothelial cells leads to endothelial-dependent vascular dysfunction with reduced nitric oxide (NO) production, increased oxidative stress, and impaired angiogenesis. Our findings show that ASLD is a unique model for studying NO-dependent endothelial dysfunction in human hypertension.


Assuntos
Argininossuccinato Liase/genética , Acidúria Argininossuccínica/genética , Células Endoteliais/patologia , Hipertensão/genética , Adolescente , Animais , Pressão Sanguínea/genética , Células Cultivadas , Criança , Modelos Animais de Doenças , Endotélio Vascular/patologia , Feminino , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Neovascularização Patológica/genética , Óxido Nítrico/genética , Estresse Oxidativo/genética , Distúrbios Congênitos do Ciclo da Ureia/genética
2.
Cardiovasc Eng Technol ; 9(1): 94-104, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29150791

RESUMO

As tissue engineering continues to mature, it is necessary to develop new technologies that bring insight into current paradigms and guide improvements for future experiments. To this end, we have developed a system to characterize our bioartificial heart model and compare them to functional native structures. In the present study, the hearts of adult Sprague-Dawley were decellularized resulting in a natural three-dimensional cardiac scaffold. Neonatal rat primary cardiac cells were then cultured within a complex 3D fibrin gel, forming a 3-dimensional cardiac construct, which was sutured to the acellular scaffold and suspended in media for 24-48 h. The resulting bioartificial hearts (BAHs) were then affixed with 16 electrodes, in different configurations to evaluate not only the electrocardiographic characteristics of the cultured tissues, but to also test the system's consistency. Histological evaluation showed cellularization and cardiac tissue formation. The BAHs and native hearts were then evaluated with our 16-channel flexible system to acquire the metrics associated with their respective electrophysiological properties. Time delays between the native signals were in the range of 0-95 ms. As well, color maps revealed a trend in impulse propagation throughout the native hearts. After evaluation of the normal rat QRS complex we found the average amplitude of the R-wave to be 5351.48 ± 44.92 µV and the average QRS duration was found to be 10.61 ± 0.18 ms. In contrast, BAHs exhibited more erratic and non-uniform activity that garnered no appreciable quantification. The data collected in this study proves our system's efficacy for EKG data procurement.


Assuntos
Potenciais de Ação , Órgãos Bioartificiais , Engenharia Biomédica/instrumentação , Eletrocardiografia/instrumentação , Coração Artificial , Miócitos Cardíacos/fisiologia , Engenharia Tecidual/instrumentação , Tecidos Suporte , Animais , Animais Recém-Nascidos , Engenharia Biomédica/métodos , Células Cultivadas , Eletrocardiografia/métodos , Feminino , Fibrina/metabolismo , Géis , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/transplante , Ratos Sprague-Dawley , Fatores de Tempo , Engenharia Tecidual/métodos
3.
PLoS One ; 11(12): e0168644, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28006821

RESUMO

Framingham Heart Study suggests that dysfunction of steroid receptor coactivator-1 may be involved in the development of hypertension. However, there is no functional evidence linking steroid receptor coactivator-1 to the regulation of blood pressure. We used immunohistochemistry to map the expression of steroid receptor coactivator-1 protein in mouse brain, especially in regions implicated in the regulation of blood pressure. Steroid receptor coactivator-1 protein was found in central amygdala, medial amygdala, supraoptic nucleus, arcuate nucleus, ventromedial, dorsomedial, paraventricular hypothalamus, and nucleus of the solitary tract. To determine the effects of steroid receptor coactivator-1 protein on cardiovascular system we measured blood pressures, blood flow velocities, echocardiographic parameters, and aortic input impedance in female steroid receptor coactivator-1 knockout mice and their wild type littermates. Steroid receptor coactivator-1 knockout mice had higher blood pressures and increased aortic stiffness when compared to female wild type littermates. Additionally, the hearts of steroid receptor coactivator-1 knockout mice seem to consume higher energy as evidenced by increased impedance and higher heart rate pressure product when compared to female wild type littermates. Our results demonstrate that steroid receptor coactivator-1 may be functionally involved in the regulation of blood pressure and aortic stiffness through the regulation of sympathetic activation in various neuronal populations.


Assuntos
Coativador 1 de Receptor Nuclear/fisiologia , Rigidez Vascular/fisiologia , Animais , Pressão Sanguínea , Ecocardiografia , Feminino , Masculino , Camundongos , Camundongos Knockout
4.
J Immunol ; 197(1): 288-95, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27206768

RESUMO

Localization of the platelet glycoprotein Ib-IX complex to the membrane lipid domain is essential for platelet adhesion to von Willebrand factor and subsequent platelet activation in vitro. Yet, the in vivo importance of this localization has never been addressed. We recently found that the disulfide linkage between Ibα and Ibß is critical for the association of Ibα with the glycosphingolipid-enriched membrane domain; in this study, we established a transgenic mouse model expressing this mutant human Ibα that is also devoid of endogenous Ibα (HαSSMα(-/-)). Characterization of this model demonstrated a similar dissociation of Ibα from murine platelet glycosphingolipid-enriched membrane to that expressed in Chinese hamster ovary cells, which correlates well with the impaired adhesion of the transgenic platelets to von Willebrand factor ex vivo and in vivo. Furthermore, we bred our transgenic mice into an atherosclerosis-prone background (HαSSMα(-/-)ApoE(-/-) and HαWTMα(-/-)ApoE(-/-)). We observed that atheroma formation was significantly inhibited in mutant mice where fewer platelet-bound CD11c(+) leukocytes were circulating (CD45(+)/CD11c(+)/CD41(+)) and residing in atherosclerotic lesions (CD45(+)/CD11c(+)), suggesting that platelet-mediated adhesion and infiltration of CD11c(+) leukocytes may be one of the mechanisms. To our knowledge, these observations provide the first in vivo evidence showing that the membrane GEM is physiologically and pathophysiologically critical in the function of the glycoprotein Ib-IX complex.


Assuntos
Aterosclerose/imunologia , Plaquetas/imunologia , Proteínas de Ligação a DNA/metabolismo , Glicoesfingolipídeos/metabolismo , Microdomínios da Membrana/metabolismo , Placa Aterosclerótica/imunologia , Complexo Glicoproteico GPIb-IX de Plaquetas/metabolismo , Trombose/imunologia , Animais , Apolipoproteínas E/genética , Aterosclerose/genética , Células CHO , Proteínas de Ligação ao Cálcio , Cricetulus , Proteínas de Ligação a DNA/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Proteínas dos Microfilamentos , Ligação Proteica , Fator de von Willebrand/metabolismo
5.
IEEE Trans Biomed Eng ; 62(6): 1614-22, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25667345

RESUMO

The purpose of this study was to develop, assess, and validate a custom 32-channel system to analyze the electrical properties of 3-D artificial heart muscle (3D-AHM). In this study, neonatal rat cardiac cells were cultured in a fibrin gel to drive the formation of 3D-AHM. Once the tissues were fully formed, the customized electrocardiogram (EKG) sensing system was used to obtain the different electrophysiological characteristics of the muscle constructs. Additionally, this system was used to evaluate the electrical properties of native rat hearts, for comparison to the fabricated tissues and native values found in the literature. Histological evaluation showed extensive cellularization and cardiac tissue formation. EKG data analysis yielded time delays between the signals ranging from 0 to 7 ms. Optical maps exhibited slight trends in impulse propagation throughout the fabricated tissue. Conduction velocities were calculated longitudinally at 277.81 cm/s, transversely at 300.79 cm/s, and diagonally at 285.68 cm/s for 3D-AHM. The QRS complex exhibited an R-wave amplitude of 438.42 ± 36.96 µV and an average duration of 317.5 ± 16.5 ms for the tissue constructs. The data collected in this study provide a clearer picture about the intrinsic properties of the 3D-AHM while proving our system's efficacy for EKG data procurement. To achieve a viable and permanent solution, the bioengineered heart muscle must physiologically resemble native heart tissue as well as mimic its electrical properties for proper contractile function. This study allows us to monitor such properties and assess the necessary changes that will improve construct development and function.


Assuntos
Técnicas Eletrofisiológicas Cardíacas/instrumentação , Miocárdio/citologia , Miócitos Cardíacos/fisiologia , Engenharia Tecidual/instrumentação , Animais , Eletrodos , Técnicas Eletrofisiológicas Cardíacas/métodos , Desenho de Equipamento , Feminino , Ratos , Ratos Sprague-Dawley , Engenharia Tecidual/métodos
6.
Am J Physiol Heart Circ Physiol ; 307(3): H284-91, 2014 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-24906918

RESUMO

The naked mole-rat (NMR) is the longest-lived rodent known, with a maximum lifespan potential (MLSP) of >31 years. Despite such extreme longevity, these animals display attenuation of many age-associated diseases and functional changes until the last quartile of their MLSP. We questioned if such abilities would extend to cardiovascular function and structure in this species. To test this, we assessed cardiac functional reserve, ventricular morphology, and arterial stiffening in NMRs ranging from 2 to 24 years of age. Dobutamine echocardiography (3 µg/g ip) revealed no age-associated changes in left ventricular (LV) function either at baseline or with exercise-like stress. Baseline and dobutamine-induced LV pressure parameters also did not change. Thus the NMR, unlike other mammals, maintains cardiac reserve with age. NMRs showed no cardiac hypertrophy, evidenced by no increase in cardiomyocyte cross-sectional area or LV dimensions with age. Age-associated arterial stiffening does not occur since there are no changes in aortic blood pressures or pulse-wave velocity. Only LV interstitial collagen deposition increased 2.5-fold from young to old NMRs (P < 0.01). However, its effect on LV diastolic function is likely minor since NMRs experience attenuated age-related increases in diastolic dysfunction in comparison with other species. Overall, these findings conform to the negligible senescence phenotype, as NMRs largely stave off cardiovascular changes for at least 75% of their MLSP. This suggests that using a comparative strategy to find factors that change with age in other mammals but not NMRs could provide novel targets to slow or prevent cardiovascular aging in humans.


Assuntos
Envelhecimento/fisiologia , Aorta/fisiologia , Frequência Cardíaca , Coração/fisiologia , Ratos-Toupeira/fisiologia , Função Ventricular Esquerda , Fatores Etários , Envelhecimento/metabolismo , Animais , Pressão Arterial , Colágeno/metabolismo , Complacência (Medida de Distensibilidade) , Ecocardiografia sob Estresse , Feminino , Longevidade , Masculino , Ratos-Toupeira/metabolismo , Miocárdio/metabolismo , Análise de Onda de Pulso , Fatores de Tempo , Rigidez Vascular
7.
J Gerontol A Biol Sci Med Sci ; 69(2): 152-9, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23682160

RESUMO

To investigate the effect of growth hormone and insulin-like growth factor 1 deficiency on the aging mouse arterial system, we compared the hemodynamics in young (4 months) and old (30 months) growth hormone-releasing hormone receptor null dwarf (Little) mice and their wild-type littermates. Young Little mice had significantly lower peak and mean aortic velocity and significantly higher aortic impedance than young wild-type mice. However, unlike the wild-type mice, there were no significant changes in arterial function with age in the Little mice. Aortic pulse wave velocity estimated using characteristic impedance increased with age in the wild-type mice, but it changed minimally in the Little mouse. We therefore conclude that arterial function in Little mice expresses a premature aging phenotype at young age and may neither enhance nor reduce their longevity.


Assuntos
Senilidade Prematura/etiologia , Envelhecimento/fisiologia , Aorta/crescimento & desenvolvimento , Aorta/fisiopatologia , Hormônio do Crescimento/fisiologia , Fator de Crescimento Insulin-Like I/fisiologia , Animais , Pressão Arterial/fisiologia , Velocidade do Fluxo Sanguíneo/fisiologia , Camundongos , Camundongos Mutantes , Fenótipo
8.
PLoS One ; 8(9): e75882, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24086656

RESUMO

Increasing evidence suggests that microRNAs are intimately involved in the pathophysiology of heart failure. MicroRNA-22 (miR-22) is a muscle-enriched miRNA required for optimum cardiac gene transcription and adaptation to hemodynamic stress by pressure overload in mice. Recent evidence also suggests that miR-22 induces hypertrophic growth and it is oftentimes upregulated in end stage heart failure. However the scope of mRNA targets and networks of miR-22 in the heart failure remained unclear. We analyzed transgenic mice with enhanced levels of miR-22 expression in adult cardiomyocytes to identify important pathophysiologic targets of miR-22. Our data shows that forced expression of miR-22 induces a pro-hypertrophic gene expression program, and it elicits contractile dysfunction leading to cardiac dilation and heart failure. Increased expression of miR-22 impairs the Ca(2+) transient, Ca(2+) loading into the sarcoplasmic reticulum plus it interferes with transcription of estrogen related receptor (ERR) and PPAR downstream genes. Mechanistically, miR-22 postranscriptionally inhibits peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), PPARα and sirtuin 1 (SIRT1) expression via a synergistic circuit, which may account for deleterious actions of unchecked miR-22 expression on the heart.


Assuntos
Regulação da Expressão Gênica/genética , Insuficiência Cardíaca/genética , MicroRNAs/genética , Retículo Sarcoplasmático/metabolismo , Animais , Cálcio/metabolismo , Insuficiência Cardíaca/patologia , Immunoblotting , Luciferases , Camundongos , Camundongos Transgênicos , MicroRNAs/metabolismo , Análise em Microsséries , Receptores Ativados por Proliferador de Peroxissomo/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Receptores Estrogênicos/metabolismo , Sirtuína 1/metabolismo , Estatísticas não Paramétricas
9.
Am J Physiol Regul Integr Comp Physiol ; 305(4): R334-42, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23761641

RESUMO

Obstructive sleep apnea (OSA), a condition in which the upper airway collapses during sleep, is strongly associated with metabolic and cardiovascular diseases. Little is known how OSA affects the cerebral circulation. The goals of this study were 1) to develop a rat model of chronic OSA that involved apnea and 2) to test the hypothesis that 4 wk of apneas during the sleep cycle alters endothelium-mediated dilations in middle cerebral arteries (MCAs). An obstruction device, which was chronically implanted into the trachea of rats, inflated to obstruct the airway 30 times/h for 8 h during the sleep cycle. After 4 wk of apneas, MCAs were isolated, pressurized, and exposed to luminally applied ATP, an endothelial P2Y2 receptor agonist that dilates through endothelial-derived nitric oxide (NO) and endothelial-dependent hyperpolarization (EDH). Dilations to ATP were attenuated ~30% in MCAs from rats undergoing apneas compared with those from a sham control group (P < 0.04 group effect; n = 7 and 10, respectively). When the NO component of the dilation was blocked to isolate the EDH component, the response to ATP in MCAs from the sham and apnea groups was similar. This finding suggests that the attenuated dilation to ATP must occur through reduced NO. In summary, we have successfully developed a novel rat model for chronic OSA that incorporates apnea during the sleep cycle. Using this model, we demonstrate that endothelial dysfunction occurred by 4 wk of apnea, likely increasing the vulnerability of the brain to cerebrovascular related accidents.


Assuntos
Trifosfato de Adenosina/farmacologia , Modelos Animais de Doenças , Endotélio Vascular/efeitos dos fármacos , Artéria Cerebral Média/efeitos dos fármacos , Agonistas do Receptor Purinérgico P2Y/farmacologia , Apneia Obstrutiva do Sono/metabolismo , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Animais , Fatores Biológicos/metabolismo , Doença Crônica , Relação Dose-Resposta a Droga , Endotélio Vascular/metabolismo , Endotélio Vascular/fisiopatologia , Masculino , Artéria Cerebral Média/metabolismo , Artéria Cerebral Média/fisiopatologia , Óxido Nítrico/metabolismo , Doadores de Óxido Nítrico/farmacologia , Óxido Nítrico Sintase Tipo III/metabolismo , Ratos , Ratos Long-Evans , Respiração , Sono , Apneia Obstrutiva do Sono/etiologia , Apneia Obstrutiva do Sono/fisiopatologia , Fatores de Tempo , Traqueia/fisiopatologia
10.
Am J Hum Genet ; 90(5): 836-46, 2012 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-22541557

RESUMO

Argininosuccinate lyase (ASL) is required for the synthesis and channeling of L-arginine to nitric oxide synthase (NOS) for nitric oxide (NO) production. Congenital ASL deficiency causes argininosuccinic aciduria (ASA), the second most common urea-cycle disorder, and leads to deficiency of both ureagenesis and NO production. Subjects with ASA have been reported to develop long-term complications such as hypertension and neurocognitive deficits despite early initiation of therapy and the absence of documented hyperammonemia. In order to distinguish the relative contributions of the hepatic urea-cycle defect from those of the NO deficiency to the phenotype, we performed liver-directed gene therapy in a mouse model of ASA. Whereas the gene therapy corrected the ureagenesis defect, the systemic hypertension in mice could be corrected by treatment with an exogenous NO source. In an ASA subject with severe hypertension refractory to antihypertensive medications, monotherapy with NO supplements resulted in the long-term control of hypertension and a decrease in cardiac hypertrophy. In addition, the NO therapy was associated with an improvement in some neuropsychological parameters pertaining to verbal memory and nonverbal problem solving. Our data show that ASA, in addition to being a classical urea-cycle disorder, is also a model of congenital human NO deficiency and that ASA subjects could potentially benefit from NO supplementation. Hence, NO supplementation should be investigated for the long-term treatment of this condition.


Assuntos
Acidúria Argininossuccínica/tratamento farmacológico , Acidúria Argininossuccínica/fisiopatologia , Terapia Genética , Óxido Nítrico/deficiência , Óxido Nítrico/farmacologia , Adolescente , Animais , Arginina/sangue , Argininossuccinato Liase/genética , Acidúria Argininossuccínica/complicações , Acidúria Argininossuccínica/genética , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Modelos Animais de Doenças , Humanos , Hipertensão/complicações , Hipertensão/tratamento farmacológico , Fígado/enzimologia , Masculino , Camundongos , Óxido Nítrico/biossíntese
11.
Circulation ; 125(22): 2751-61, 2012 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-22570371

RESUMO

BACKGROUND: Delineating the role of microRNAs (miRNAs) in the posttranscriptional gene regulation offers new insights into how the heart adapts to pathological stress. We developed a knockout of miR-22 in mice and investigated its function in the heart. METHODS AND RESULTS: Here, we show that miR-22-deficient mice are impaired in inotropic and lusitropic response to acute stress by dobutamine. Furthermore, the absence of miR-22 sensitized mice to cardiac decompensation and left ventricular dilation after long-term stimulation by pressure overload. Calcium transient analysis revealed reduced sarcoplasmic reticulum Ca(2+) load in association with repressed sarcoplasmic reticulum Ca(2+) ATPase activity in mutant myocytes. Genetic ablation of miR-22 also led to a decrease in cardiac expression levels for Serca2a and muscle-restricted genes encoding proteins in the vicinity of the cardiac Z disk/titin cytoskeleton. These phenotypes were attributed in part to inappropriate repression of serum response factor activity in stressed hearts. Global analysis revealed increased expression of the transcriptional/translational repressor purine-rich element binding protein B, a highly conserved miR-22 target implicated in the negative control of muscle expression. CONCLUSION: These data indicate that miR-22 functions as an integrator of Ca(2+) homeostasis and myofibrillar protein content during stress in the heart and shed light on the mechanisms that enhance propensity toward heart failure.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/fisiopatologia , MicroRNAs/genética , MicroRNAs/metabolismo , Contração Miocárdica/fisiologia , Estresse Fisiológico/fisiologia , Animais , Cálcio/metabolismo , Cardiomiopatia Dilatada/patologia , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica/fisiologia , Homeostase/fisiologia , Masculino , Camundongos , Camundongos Knockout , Miocárdio/metabolismo , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Fator de Resposta Sérica/metabolismo
12.
Nat Med ; 17(12): 1619-26, 2011 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-22081021

RESUMO

Nitric oxide (NO) is crucial in diverse physiological and pathological processes. We show that a hypomorphic mouse model of argininosuccinate lyase (encoded by Asl) deficiency has a distinct phenotype of multiorgan dysfunction and NO deficiency. Loss of Asl in both humans and mice leads to reduced NO synthesis, owing to both decreased endogenous arginine synthesis and an impaired ability to use extracellular arginine for NO production. Administration of nitrite, which can be converted into NO in vivo, rescued the manifestations of NO deficiency in hypomorphic Asl mice, and a nitric oxide synthase (NOS)-independent NO donor restored NO-dependent vascular reactivity in humans with ASL deficiency. Mechanistic studies showed that ASL has a structural function in addition to its catalytic activity, by which it contributes to the formation of a multiprotein complex required for NO production. Our data demonstrate a previously unappreciated role for ASL in NOS function and NO homeostasis. Hence, ASL may serve as a target for manipulating NO production in experimental models, as well as for the treatment of NO-related diseases.


Assuntos
Argininossuccinato Liase/metabolismo , Acidúria Argininossuccínica/metabolismo , Óxido Nítrico/biossíntese , Óxido Nítrico/deficiência , Animais , Arginina/farmacologia , Argininossuccinato Sintase/metabolismo , Acidúria Argininossuccínica/genética , Linhagem Celular , Modelos Animais de Doenças , Células Endoteliais , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Técnicas de Silenciamento de Genes , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Óxido Nítrico Sintase/metabolismo , Nitritos/metabolismo , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Análise de Sequência de DNA , Suínos
13.
Hypertension ; 58(4): 672-8, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21876070

RESUMO

K(2P)6.1, a member of the 2-pore domain K channel family, is highly expressed in the vascular system; however, its function is unknown. We tested the following hypotheses. K(2P)6.1 regulates the following: (1) systemic blood pressure; (2) the contractile state of arteries; (3) vascular smooth muscle cell migration; (4) proliferation; and/or (5) volume regulation. Mice lacking K(2P)6.1 (KO) were generated by deleting exon 1 of Kcnk6. Mean arterial blood pressure in both anesthetized and awake KO mice was increased by 17±2 and 26±3 mm Hg, respectively (P<0.05). The resting membrane potential in freshly dispersed vascular smooth muscle cells was depolarized by 17±2 mV in the KO compared with wild-type littermates (P<0.05). The contractile responses to KCl (P<0.05) and BAY K 8644 (P<0.01), an activator of L-type calcium channels, were enhanced in isolated segments of aorta from KO mice. However, there was no difference in the current density of L-type calcium channels. Responses to U46619, an agent that activates rho kinase, showed an enhanced contraction in aorta from KO mice (P<0.001). The BAY K 8644-mediated increase in contraction was decreased to wild-type levels when treated with Y27632, a rho kinase inhibitor, (P<0.05). K(2P)6.1 does not appear to be involved with migration, proliferation, or volume regulation in cultured vascular smooth muscle cells. We conclude that K(2P)6.1 deficiency induces vascular dysfunction and hypertension through a mechanism that may involve smooth muscle cell depolarization and enhanced rho kinase activity.


Assuntos
Aorta/fisiopatologia , Hipertensão/etiologia , Hipertensão/fisiopatologia , Músculo Liso Vascular/fisiopatologia , Canais de Potássio de Domínios Poros em Tandem/fisiologia , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacologia , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Animais , Aorta/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Agonistas dos Canais de Cálcio/farmacologia , Modelos Animais de Doenças , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Camundongos , Camundongos Knockout , Músculo Liso Vascular/efeitos dos fármacos , Canais de Potássio de Domínios Poros em Tandem/deficiência , Canais de Potássio de Domínios Poros em Tandem/genética , Cloreto de Potássio/farmacologia , Vasoconstrição/efeitos dos fármacos , Vasoconstrição/fisiologia , Vasoconstritores/farmacologia , Quinases Associadas a rho/fisiologia
14.
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
15.
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
16.
Ultrasound Med Biol ; 36(7): 1169-75, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20620703

RESUMO

If volume flow was measured at each end of an arterial segment with no branches, any instantaneous differences would indicate that volume was increasing or decreasing transiently within the segment. This concept could provide an alternative method to assess the mechanical properties or distensibility of an artery noninvasively using ultrasound. The goal of this study was to determine the feasibility of using Doppler measurements of pulsatile velocity (opposed to flow) at two sites to estimate the volume pulsations of the intervening arterial segment. To test the concept over a wide range of dimensions, we made simultaneous measurements of velocity in a short 5 mm segment of a mouse common carotid artery and in a longer 20 cm segment of a human brachial-radial artery using a two-channel 20 MHz pulsed Doppler and calculated the waveforms and magnitudes of the volume pulsations during the cardiac cycle. We also estimated pulse wave velocity from the velocity upstroke arrival times and measured artery wall motion using tissue Doppler methods for comparison of magnitudes and waveforms. Volume pulsations estimated from Doppler velocity measurements were 16% for the mouse carotid artery and 4% for the human brachial artery. These values are consistent with the measured pulse wave velocities of 4.2 m/s and 10 m/s, respectively, and with the mouse carotid diameter pulsation. In addition, the segmental volume waveforms resemble diameter and pressure waveforms as expected. We conclude that with proper application and further validation, dual Doppler velocity measurements can be used to estimate the magnitude and waveform of volume pulsations of an arterial segment and to provide an alternative noninvasive index of arterial mechanical properties.


Assuntos
Artérias/diagnóstico por imagem , Artérias/fisiologia , Volume Sanguíneo/fisiologia , Interpretação de Imagem Assistida por Computador/métodos , Fluxo Pulsátil/fisiologia , Ultrassonografia Doppler/métodos , Animais , Velocidade do Fluxo Sanguíneo/fisiologia , Estudos de Viabilidade , Humanos , Camundongos
17.
Am J Physiol Regul Integr Comp Physiol ; 299(2): R461-9, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20357027

RESUMO

We tested the hypothesis that TREK-1, a two-pore domain K channel, is involved with dilations in arteries. Because there are no selective activators or inhibitors of TREK-1, we generated a mouse line deficient in TREK-1. Endothelium-mediated dilations were not different in arteries from wild-type (WT) and TREK-1 knockout (KO) mice. This includes dilations of the middle cerebral artery to ATP, dilations of the basilar artery to ACh, and relaxations of the aorta to carbachol, a cholinergic agonist. The nitric oxide (NO) and endothelium-dependent hyperpolarizing factor components of ATP dilations were identical in the middle cerebral arteries of WT and TREK-1 KO mice. Furthermore, the NO and cyclooxygenase-dependent components were identical in the basilar arteries of the different genotypes. Dilations of the basilar artery to alpha-linolenic acid, an activator of TREK-1, were not affected by the absence of TREK-1. Whole cell currents recorded using patch-clamp techniques were similar in cerebrovascular smooth muscle cells (CVSMCs) from WT and TREK-1 KO mice. alpha-linolenic acid or arachidonic acid increased whole cell currents in CVSMCs from both WT and TREK-1 KO mice. The selective blockers of large-conductance Ca-activated K channels, penitrem A and iberiotoxin, blocked the increased currents elicited by either alpha-linolenic or arachidonic acid. In summary, dilations were similar in arteries from WT and TREK-1 KO mice. There was no sign of TREK-1-like currents in CVSMCs from WT mice, and there were no major differences in currents between the genotypes. We conclude that regulation of arterial diameter is not altered in mice lacking TREK-1.


Assuntos
Artéria Basilar/metabolismo , Circulação Cerebrovascular , Artéria Cerebral Média/metabolismo , Canais de Potássio de Domínios Poros em Tandem/deficiência , Potássio/metabolismo , Vasodilatação , Potenciais de Ação , Animais , Aorta/metabolismo , Ácido Araquidônico/metabolismo , Artéria Basilar/efeitos dos fármacos , Circulação Cerebrovascular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Genótipo , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Artéria Cerebral Média/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , Óxido Nítrico/metabolismo , Fenótipo , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio de Domínios Poros em Tandem/genética , Prostaglandina-Endoperóxido Sintases/metabolismo , Vasoconstrição , Vasoconstritores/farmacologia , Vasodilatação/efeitos dos fármacos , Vasodilatadores/farmacologia , Ácido alfa-Linoleico/metabolismo
18.
J Clin Invest ; 120(2): 472-84, 2010 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-20071776

RESUMO

PDGFR is an important target for novel anticancer therapeutics because it is overexpressed in a wide variety of malignancies. Recently, however, several anticancer drugs that inhibit PDGFR signaling have been associated with clinical heart failure. Understanding this effect of PDGFR inhibitors has been difficult because the role of PDGFR signaling in the heart remains largely unexplored. As described herein, we have found that PDGFR-beta expression and activation increase dramatically in the hearts of mice exposed to load-induced cardiac stress. In mice in which Pdgfrb was knocked out in the heart in development or in adulthood, exposure to load-induced stress resulted in cardiac dysfunction and heart failure. Mechanistically, we showed that cardiomyocyte PDGFR-beta signaling plays a vital role in stress-induced cardiac angiogenesis. Specifically, we demonstrated that cardiomyocyte PDGFR-beta was an essential upstream regulator of the stress-induced paracrine angiogenic capacity (the angiogenic potential) of cardiomyocytes. These results demonstrate that cardiomyocyte PDGFR-beta is a regulator of the compensatory cardiac response to pressure overload-induced stress. Furthermore, our findings may provide insights into the mechanism of cardiotoxicity due to anticancer PDGFR inhibitors.


Assuntos
Coração/fisiopatologia , Miócitos Cardíacos/fisiologia , Receptor beta de Fator de Crescimento Derivado de Plaquetas/fisiologia , Animais , Peso Corporal , Circulação Coronária , Coração/anatomia & histologia , Coração/efeitos dos fármacos , Coração/fisiologia , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/patologia , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/prevenção & controle , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Tamanho do Órgão , Fosforilação , Receptor beta de Fator de Crescimento Derivado de Plaquetas/deficiência , Receptor beta de Fator de Crescimento Derivado de Plaquetas/genética , Transdução de Sinais , Volume Sistólico , Suporte de Carga
19.
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
20.
Conf Proc IEEE Eng Med Biol Soc ; 2009: 1104-5, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19964748

RESUMO

Isoflurane is the most commonly used anesthetic in mice. We studied the effect of low and high levels of isoflurane (also a potent coronary vasodilator) on aortic impedance in mice. Aortic impedance was determined using pressure and flow velocity signals at baseline (B, pentobarbital anesthesia), low (Isol, 1%), and high (Iso2.5, 2.5%) levels of isoflurane. Significant differences were observed in peak and mean flow velocities, systolic, diastolic, mean and pulse pressures at B and Iso2.5. However in impedance indices only peripheral vascular resistance was significantly different. No changes were observed in the harmonic components that represent pulsatile characteristics of the aorta. Peak left ventricular (LV) pressure was significantly lower at Iso2.5 when compared to B, but +/-dP/dt and tau (time constant of LV relaxation) did not change significantly indicating that LV contractility was unaffected. These results show that various levels of isoflurane cause significant changes in vascular hemodynamics and care must be taken to minimize these differences when using isoflurane as an anesthesia.


Assuntos
Anestésicos Inalatórios/farmacologia , Aorta/efeitos dos fármacos , Isoflurano/farmacologia , Resistência Vascular/efeitos dos fármacos , Animais , Aorta/fisiologia , Engenharia Biomédica , Circulação Coronária/efeitos dos fármacos , Hemodinâmica/efeitos dos fármacos , Camundongos , Vasodilatadores/farmacologia
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