RESUMO
PURPOSE OF REVIEW: Pulse wave velocity (PWV) is an important and well-established measure of arterial stiffness that is strongly associated with aging. Age-related alterations in the elastic properties and integrity of arterial walls can lead to cardiovascular disease. PWV measurements play an important role in the early detection of these changes, as well as other cardiovascular disease risk factors, such as hypertension. This review provides a comprehensive summary of the current knowledge of the effects of aging on arterial stiffness, as measured by PWV. RECENT FINDINGS: This review highlights recent findings showing the applicability of PWV analysis for investigating heart failure, hypertension, and other cardiovascular diseases, as well as cerebrovascular diseases and Alzheimer's disease. It also discusses the clinical implications of utilizing PWV to monitor treatment outcomes, various challenges in implementing PWV assessment in clinical practice, and the development of new technologies, including machine learning and artificial intelligence, which may improve the usefulness of PWV measurements in the future. Measuring arterial stiffness through PWV remains an important technique to study aging, especially as the technology continues to evolve. There is a clear need to leverage PWV to identify interventions that mitigate age-related increases in PWV, potentially improving CVD outcomes and promoting healthy vascular aging.
Assuntos
Doenças Cardiovasculares , Hipertensão , Rigidez Vascular , Humanos , Hipertensão/tratamento farmacológico , Doenças Cardiovasculares/etiologia , Análise de Onda de Pulso/métodos , Inteligência Artificial , ArtériasRESUMO
With sparse treatment options, cardiac disease remains a significant cause of death among humans. As a person ages, mitochondria breakdown and the heart becomes less efficient. Heart failure is linked to many mitochondria-associated processes, including endoplasmic reticulum stress, mitochondrial bioenergetics, insulin signaling, autophagy, and oxidative stress. The roles of key mitochondrial complexes that dictate the ultrastructure, such as the mitochondrial contact site and cristae organizing system (MICOS), in aging cardiac muscle are poorly understood. To better understand the cause of age-related alteration in mitochondrial structure in cardiac muscle, we used transmission electron microscopy (TEM) and serial block facing-scanning electron microscopy (SBF-SEM) to quantitatively analyze the three-dimensional (3-D) networks in cardiac muscle samples of male mice at aging intervals of 3 mo, 1 yr, and 2 yr. Here, we present the loss of cristae morphology, the inner folds of the mitochondria, across age. In conjunction with this, the three-dimensional (3-D) volume of mitochondria decreased. These findings mimicked observed phenotypes in murine cardiac fibroblasts with CRISPR/Cas9 knockout of Mitofilin, Chchd3, Chchd6 (some members of the MICOS complex), and Opa1, which showed poorer oxidative consumption rate and mitochondria with decreased mitochondrial length and volume. In combination, these data show the need to explore if loss of the MICOS complex in the heart may be involved in age-associated mitochondrial and cristae structural changes.NEW & NOTEWORTHY This article shows how mitochondria in murine cardiac changes, importantly elucidating age-related changes. It also is the first to show that the MICOS complex may play a role in outer membrane mitochondrial structure.
Assuntos
Mitocôndrias , Miocárdio , Humanos , Masculino , Camundongos , Animais , Mitocôndrias/metabolismo , Miocárdio/metabolismo , Coração , Envelhecimento , Transdução de Sinais , Proteínas Mitocondriais/metabolismoRESUMO
Cattle belonging to seven different genetic groups in Kerala state, India were chosen for the study to find out the genetic diversity between the groups, which would aid in their sustainable improvement and conservation of native cattle. They included the native groups namely, Vechur, Kasaragod, Vadakara dwarf and Vilwadri, along with three different grades of crossbred cattle, based on milk production. Genomic DNA was isolated from 20 to 30 unrelated animals of each group and a panel of 25 microsatellite markers as suggested by FAO-ISAG, were amplified by multiplex PCR. The PCR amplicons were genotyped and the allelic data analyzed using suitable Bioinformatics softwares. The present study showed that the observed number of alleles was much more than the expected, in all populations. The mean PIC value obtained for the present study was 0.8912 and increased number of private alleles were observed, especially in Vilwadri and Kasaragod groups. Negative value of FIS (-0.055) indicated that the level of inbreeding was less. The FST value was 0.1442 indicating that the populations showed good genetic differentiation. The results of Structure analysis revealed admixture only in Vadakara population. The results obtained from the present study showed that Vilwadri and Kasaragod cattle showed distinct differences from other groups.
Assuntos
Variação Genética , Endogamia , Animais , Bovinos/genética , Variação Genética/genética , Genótipo , Repetições de Microssatélites/genética , Reação em Cadeia da Polimerase MultiplexRESUMO
We analyzed the effect of a single nucleotide polymorphism, g. C3141T in the 3' UTR of Signal transducer and activator of transcription-1 gene (STAT1) on milk production traits in the Holstein Friesian crossbred cattle of Kerala (n = 144) by association analysis and expression study. The population was genotyped by restriction fragment length polymorphism using Pag1. Association study using the General Linear Model-Analysis of Variance revealed that none of the yield or composition traits analyzed were significantly differed. The expression profile of STAT1 gene in leucocytes of animals bearing homozygous genotypes was compared by quantitative real time PCR using SYBR green chemistry with and relative expression was not found to be significantly differed. The second stage of the study, the STAT1 mRNA spanning 3213 bp was amplified from leucocytes and sequenced (GenBank: MT459802.1). Two novel SNPs were identified; one synonymous mutation in the coding region (g.A1212G) and the other in the 3'UTR (g.T3042C). The novel SNPs might contribute to STAT1 gene regulation mediated by alternate spicing or binding sites for regulatory molecules. The results reiterate the importance of extensive studies of STAT1 gene variants to substantiate the presence of a quantitative trait loci for dairy traits in the vicinity of STAT1 gene.
Assuntos
Leite , Locos de Características Quantitativas , Animais , Bovinos/genética , Feminino , Locos de Características Quantitativas/genética , Leite/química , Polimorfismo de Nucleotídeo Único/genética , Genótipo , Fenótipo , Lactação/genéticaRESUMO
The incidence of diastolic dysfunction increases with age in both humans and mice. This is characterized by increased passive stiffness and slower relaxation of the left ventricle. The stiffness arises at least partially from progressively increased interstitial collagen deposition because of highly secretory fibroblasts. In the past, we demonstrated that AMPK activation via the drug 5-aminoimidazole-4-carboxamide riboside (AICAR) in middle-aged mice reduced adverse remodeling after myocardial infarction. Therefore, as an attempt to normalize the fibroblast phenotype, we used 21-mo-old male and female mice and treated them with AICAR (0.166 mg/g body wt) where each mouse was followed in a functional study over a 3-mo period. We found sex-related differences in extracellular matrix (ECM) composition as well as heart function indices at baseline, which were further accentuated by AICAR treatment. AICAR attenuated the age-related increase in left atrial volume (LAV, an indicator of diastolic dysfunction) in female but not in male hearts, which was associated with reduced collagen deposition in the old female heart, and reduced the transcription factor Gli1 expression in cardiac fibroblasts. We further demonstrated that collagen synthesis was dependent on Gli1, which is a target of AMPK-mediated degradation. By contrast, AICAR had a minor impact on cardiac fibroblasts in the old male heart because of blunted AMPK phosphorylation. Hence, it did not significantly improve old male heart function indices. In conclusion, we demonstrated that male and female hearts are phenotypically different, and sex-specific differences need to be considered when analyzing the response to pharmacological intervention.NEW & NOTEWORTHY The aging heart develops diastolic dysfunction because of increased collagen deposition. We attempted to reduce collagen expression in the old heart by activating AMPK using AICAR. An improvement of diastolic function and reduction of cardiac fibrosis was found only in the female heart and correlated with decreased procollagen expression and increased degradation of the transcription factor Gli1. Male hearts display blunted AICAR-dependent AMPK activation and therefore this treatment had no benefits for the male mice.
Assuntos
Proteínas Quinases Ativadas por AMP , Cardiomiopatias , Proteínas Quinases Ativadas por AMP/metabolismo , Envelhecimento/metabolismo , Aminoimidazol Carboxamida/farmacologia , Animais , Colágeno/metabolismo , Feminino , Fibrose , Masculino , Camundongos , Fenótipo , Proteína GLI1 em Dedos de Zinco/genéticaRESUMO
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/genéticaRESUMO
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/metabolismoRESUMO
There is a dearth of approaches to experimentally direct cell migration by continuously varying signal input to a single cell, evoking all possible migratory responses and quantitatively monitoring the cellular and molecular response dynamics. Here we used a visual blue opsin to recruit the endogenous G-protein network that mediates immune cell migration. Specific optical inputs to this optical trigger of signaling helped steer migration in all possible directions with precision. Spectrally selective imaging was used to monitor cell-wide phosphatidylinositol (3,4,5)-triphosphate (PIP3), cytoskeletal, and cellular dynamics. A switch-like PIP3 increase at the cell front and a decrease at the back were identified, underlying the decisive migratory response. Migration was initiated at the rapidly increasing switch stage of PIP3 dynamics. This result explains how a migratory cell filters background fluctuations in the intensity of an extracellular signal but responds by initiating directionally sensitive migration to a persistent signal gradient across the cell. A two-compartment computational model incorporating a localized activator that is antagonistic to a diffusible inhibitor was able to simulate the switch-like PIP3 response. It was also able simulate the slow dissipation of PIP3 on signal termination. The ability to independently apply similar signaling inputs to single cells detected two cell populations with distinct thresholds for migration initiation. Overall the optical approach here can be applied to understand G-protein-coupled receptor network control of other cell behaviors.
Assuntos
Movimento Celular/fisiologia , Proteínas de Ligação ao GTP/metabolismo , Luz , Modelos Biológicos , Opsinas de Bastonetes/metabolismo , Opsinas de Bastonetes/efeitos da radiação , Transdução de Sinais/efeitos da radiação , Animais , Linhagem Celular , Movimento Celular/efeitos da radiação , Camundongos , Fosfatos de Fosfatidilinositol/metabolismoRESUMO
Innate immune mechanism plays a key role in mammary defense, from recognition of pathogens to activation of nonspecific and specific immunity involved in elimination of pathogens. Expression profiles of innate immune response genes namely Toll like receptor 2 (TLR-2), Peptidoglycan recognition protein 1 (PGLYRP-1), Interleukin 8 receptor (IL-8 R), L-Selectin (SELL), and Osteopontin (OPN) in milk somatic cells of subclinical mastitis (SCM) affected crossbred cows were investigated under this study at transcript level using quantitative real time polymerase chain reaction (qRT-PCR). Dairy cows in mid lactation were screened for SCM using California Mastitis Test (CMT), Somatic Cell Count (SCC) and Electrical Conductivity test (EC). Based on results of SCM screening tests, crossbred cows were clustered into two groups with four Staphylococcus aureus infected SCM cows and four apparently healthy cows. The expressions levels of TLR-2, PGLYRP-1, IL-8 R, SELL, and OPN in milk somatic cells of SCM affected cows were significantly higher (p < 0.05) than healthy cows. These genes could be considered as candidate genes for innate immune response against S. aureus SCM infection.
Assuntos
Imunidade Inata , Mastite Bovina/imunologia , Leite/citologia , Leite/imunologia , Animais , Bovinos , Células Cultivadas , Citocinas/análise , Citocinas/genética , Citocinas/metabolismo , Feminino , Perfilação da Expressão Gênica , Imunidade Inata/genética , Imunidade Inata/imunologia , Selectina L/análise , Selectina L/genética , Selectina L/metabolismo , Receptor 2 Toll-Like/análise , Receptor 2 Toll-Like/genética , Receptor 2 Toll-Like/metabolismoRESUMO
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/biossínteseRESUMO
G-protein ßγ subunits translocate reversibly from the plasma membrane to internal membranes on receptor activation. Translocation rates differ depending on the γ subunit type. There is limited understanding of the role of the differential rates of Gßγ translocation in modulating signaling dynamics in a cell. Bifurcation analysis of the calcium oscillatory network structure predicts that the translocation rate of a signaling protein can regulate the damping of system oscillation. Here, we examined whether the Gßγ translocation rate regulates calcium oscillations induced by G-protein-coupled receptor activation. Oscillations in HeLa cells expressing γ subunit types with different translocation rates were imaged and quantitated. The results show that differential Gßγ translocation rates can underlie the diversity in damping characteristics of calcium oscillations among cells. Mathematical modeling shows that a translocation embedded motif regulates damping of G-protein-mediated calcium oscillations consistent with experimental data. The current study indicates that such a motif may act as a tuning mechanism to design oscillations with varying damping patterns by using intracellular translocation of a signaling component.
Assuntos
Sinalização do Cálcio , Subunidades beta da Proteína de Ligação ao GTP/metabolismo , Subunidades gama da Proteína de Ligação ao GTP/metabolismo , Modelos Biológicos , Membrana Celular/metabolismo , Retroalimentação Fisiológica , Subunidades beta da Proteína de Ligação ao GTP/química , Subunidades gama da Proteína de Ligação ao GTP/química , Células HeLa , HumanosRESUMO
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 VascularRESUMO
Alzheimer's Disease (AD) is a global health issue, affecting over 6 million in the United States, with that number expected to increase as the aging population grows. As a neurodegenerative disorder that affects memory and cognitive functions, it is well established that AD is associated with cardiovascular risk factors beyond only cerebral decline. However, the study of cerebrovascular techniques for AD is still evolving. Here, we provide reproducible methods to measure impedance-based pulse wave velocity (PWV), a marker of arterial stiffness, in the systemic vascular (aortic PWV) and in the cerebral vascular (cerebral PWV) systems. Using aortic impedance and this relatively novel technique of cerebral impedance to comprehensively describe the systemic vascular and the cerebral vascular systems, we examined the sex-dependent differences in 5x transgenic mice (5XFAD) with AD under normal and high-fat diet, and in wild-type mice under a normal diet. Additionally, we validated our method for measuring cerebrovascular impedance in a model of induced stress in 5XFAD. Together, our results show that sex and diet differences in wildtype and 5XFAD mice account for very minimal differences in cerebral impedance. Interestingly, 5XFAD, and not wildtype, male mice on a chow diet show higher cerebral impedance, suggesting pathological differences. Opposingly, when we subjected 5XFAD mice to stress, we found that females showed elevated cerebral impedance. Using this validated method of measuring impedance-based aortic and cerebral PWV, future research may explore the effects of modifying factors including age, chronic diet, and acute stress, which may mediate cardiovascular risk in AD.
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/metabolismoRESUMO
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/fisiopatologiaRESUMO
Introduction: Heart failure (HF) is the leading cause of death worldwide. Most large and small animal disease models of HF are based on surgical procedures. A common surgical technique to induce HF is transverse aortic constriction (TAC), which induces pressure overload. The conventional TAC (cTAC) procedure is a highly invasive surgery that is associated with severe inflammation and excessive perioperative deaths. Aim: To establish an improved, minimally invasive TAC (mTAC) procedure that does not require thoracotomy. Methods and results: Following anesthesia, mice were intubated, and a small incision was made at the neck and chest. After cutting the sternum about 4 mm, the aortic arch was approached without opening the pleural cavity. A suture was placed between the brachiocephalic artery and the left common carotid artery. This model was associated with low perioperative mortality and a highly reproducible constriction evidenced by an increased right-to-left carotid blood flow velocity ratio in mTAC mice (5.9 ± 0.2) vs. sham controls (1.2 ± 0.1; P < 0.001). mTAC mice exhibited progressive cardiac remodeling during the 8 weeks post-TAC, resulting in reduced left ventricular (LV) contractility, increased LV end-systolic diameter, left atrial enlargement and diastolic dysfunction, and an increased heart weight to tibia length ratio (mTAC: 15.0 ± 0.8 vs. sham: 10.1 ± 0.6; P < 0.01). Conclusion: Our data show that the mTAC procedure yields a highly reproducible phenotype consisting of LV contractile dysfunction and enlargement, combined with left atrial enlargement and diastolic dysfunction. Potential impact of the findings: This model may be used to test the molecular mechanisms underlying atrial remodeling associated with HF development or to evaluate therapeutic strategies to treat these conditions.
RESUMO
Introduction: Many studies in mice have demonstrated that cardiac-specific innate immune signaling pathways can be reprogrammed to modulate inflammation in response to myocardial injury and improve outcomes. While the echocardiography standard parameters of left ventricular (LV) ejection fraction, fractional shortening, end-diastolic diameter, and others are used to assess cardiac function, their dependency on loading conditions somewhat limits their utility in completely reflecting the contractile function and global cardiovascular efficiency of the heart. A true measure of global cardiovascular efficiency should include the interaction between the ventricle and the aorta (ventricular-vascular coupling, VVC) as well as measures of aortic impedance and pulse wave velocity. Methods: We measured cardiac Doppler velocities, blood pressures, along with VVC, aortic impedance, and pulse wave velocity to evaluate global cardiac function in a mouse model of cardiac-restricted low levels of TRAF2 overexpression that conferred cytoprotection in the heart. Results: While previous studies reported that response to myocardial infarction and reperfusion was improved in the TRAF2 overexpressed mice, we found that TRAF2 mice had significantly lower cardiac systolic velocities and accelerations, diastolic atrial velocity, aortic pressures, rate-pressure product, LV contractility and relaxation, and stroke work when compared to littermate control mice. Also, we found significantly longer aortic ejection time, isovolumic contraction and relaxation times, and significantly higher mitral early/atrial ratio, myocardial performance index, and ventricular vascular coupling in the TRAF2 overexpression mice compared to their littermate controls. We found no significant differences in the aortic impedance and pulse wave velocity. Discussion: While the reported tolerance to ischemic insults in TRAF2 overexpression mice may suggest enhanced cardiac reserve, our results indicate diminished cardiac function in these mice.
RESUMO
During aging, muscle gradually undergoes sarcopenia, the loss of function associated with loss of mass, strength, endurance, and oxidative capacity. However, the 3D structural alterations of mitochondria associated with aging in skeletal muscle and cardiac tissues are not well described. Although mitochondrial aging is associated with decreased mitochondrial capacity, the genes responsible for the morphological changes in mitochondria during aging are poorly characterized. We measured changes in mitochondrial morphology in aged murine gastrocnemius, soleus, and cardiac tissues using serial block-face scanning electron microscopy and 3D reconstructions. We also used reverse transcriptase-quantitative PCR, transmission electron microscopy quantification, Seahorse analysis, and metabolomics and lipidomics to measure changes in mitochondrial morphology and function after loss of mitochondria contact site and cristae organizing system (MICOS) complex genes, Chchd3, Chchd6, and Mitofilin. We identified significant changes in mitochondrial size in aged murine gastrocnemius, soleus, and cardiac tissues. We found that both age-related loss of the MICOS complex and knockouts of MICOS genes in mice altered mitochondrial morphology. Given the critical role of mitochondria in maintaining cellular metabolism, we characterized the metabolomes and lipidomes of young and aged mouse tissues, which showed profound alterations consistent with changes in membrane integrity, supporting our observations of age-related changes in muscle tissues. We found a relationship between changes in the MICOS complex and aging. Thus, it is important to understand the mechanisms that underlie the tissue-dependent 3D mitochondrial phenotypic changes that occur in aging and the evolutionary conservation of these mechanisms between Drosophila and mammals.
Assuntos
Imageamento Tridimensional , Membranas Associadas à Mitocôndria , Camundongos , Animais , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , DNA Mitocondrial/metabolismo , Proteínas Mitocondriais/metabolismo , Mamíferos/genética , Mamíferos/metabolismoRESUMO
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/instrumentaçãoRESUMO
OBJECTIVES: The presence of comorbidities such as cardiovascular disease, peripheral vascular disease, and chronic renal disease, or and the prevention of these ailments in diabetics, frequently demands multiple drug treatments, increasing the risk of drug-drug interactions (DDIs). The current study was focused on identifying possible DDIs on concomitant administration of losartan, a drug used to regulate hypertension along with a combination of glimepiride + metformin, widely used to treat diabetes mellitus. Possible pharmacodynamic and pharmacokinetic interactions were observed for, following single-dose as well as multiple-dose treatment protocols in normal and alloxan-induced diabetes in albino Wistar rats and rabbits. MATERIALS AND METHODS: Blood samples from surviving rats/rabbits obtained through orbital venous sinus bleeding/marginal ear vein bleeding, respectively, at predetermined intervals and put through to biochemical estimations of sugar level in the blood by Glucose oxidase/peroxidase method; insulin levels in serum using the enzyme-linked immunosorbent assay and serum glimepiride levels using the high-performance liquid chromatography. RESULTS AND DISCUSSION: Losartan, when treated as a single drug, resulted in a slight lowering of blood glucose levels in normal rats, diabetic rats and normal rabbits. Hypoglycemic activity of a combination of glimepiride + metformin was enhanced when losartan was co-administered as a single dosage schedule as well as a multiple dose schedule as indicated by a reduced blood glucose level and enhanced levels of insulin in rats as well as in rabbits. Serum glimepiride levels were also higher and pharmacokinetic parameters of glimepiride including mean residence time, Cmax, T1/2, AUMC0-∞, AUMC0-t, and AUC0-∞, were significantly higher, whereas its clearance was decreased in the two regimens of losartan that was followed. CONCLUSION: It can therefore be concluded, that in diabetics with hypertension as a comorbidity condition, co-administration of losartan with glimepiride + metformin should be avoided or the dosage of a combination of glimepiride + metformin needs to be tittered to avoid recurrence of hypoglycemic episodes.