Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 3.303
Filtrar
1.
Ann Intern Med ; 174(7): ITC97-ITC112, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34251902

RESUMO

This review focuses on the diagnosis and management of menopause, highlighting both hormonal and nonhormonal treatment options. In particular, the article focuses on recent data on the risks and benefits of hormone therapy to help clinicians better counsel their patients about decision making with regard to understanding and treating menopause symptoms.


Assuntos
Menopausa/fisiologia , Neoplasias da Mama/etiologia , Doenças Cardiovasculares/prevenção & controle , Transtornos Cognitivos/etiologia , Contraindicações de Medicamentos , Terapia de Reposição de Estrogênios/efeitos adversos , Feminino , Estilo de Vida Saudável , Fogachos/tratamento farmacológico , Fogachos/terapia , Humanos , Menopausa/sangue , Menopausa/psicologia , Osteoporose Pós-Menopausa/prevenção & controle , Educação de Pacientes como Assunto , Medição de Risco , Inibidores de Captação de Serotonina/uso terapêutico , Sudorese/fisiologia , Vagina/fisiologia , Sistema Vasomotor/fisiologia
2.
Am J Physiol Heart Circ Physiol ; 320(6): H2401-H2415, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33989080

RESUMO

Cardiovascular adaptation underlies all athletic training modalities, with a variety of factors contributing to overall response during exercise-induced stimulation. In this regard the role of circulating biomarkers is a well-established and invaluable tool for monitoring cardiovascular function. Specifically, novel biomarkers such as circulating cell free DNA and RNA are now becoming attractive tools for monitoring cardiovascular function with the advent of next generation technologies that can provide unprecedented precision and resolution of these molecular signatures, paving the way for novel diagnostic and prognostic avenues to better understand physiological remodeling that occurs in trained versus untrained states. In particular, microRNAs are a species of regulatory RNAs with pleiotropic effects on multiple pathways in tissue-specific manners. Furthermore, the identification of cell free microRNAs within peripheral circulation represents a distal signaling mechanism that is just beginning to be explored via a diversity of molecular and bioinformatic approaches. This article provides an overview of the emerging field of sports/performance genomics with a focus on the role of microRNAs as novel functional diagnostic and prognostic tools, and discusses present knowledge in the context of athletic vascular remodeling. This review concludes with current advantages and limitations, touching upon future directions and implications for applying contemporary systems biology knowledge of exercise-induced physiology to better understand how disruption can lead to pathology.


Assuntos
MicroRNA Circulante/genética , Endotélio Vascular/metabolismo , Exercício Físico/fisiologia , Remodelação Vascular/genética , Animais , Ácidos Nucleicos Livres , MicroRNA Circulante/metabolismo , Endotélio Vascular/fisiologia , Treino Aeróbico , Humanos , Inflamação/genética , Neovascularização Fisiológica/genética , Condicionamento Físico Animal/fisiologia , Estresse Mecânico , Trombose/genética , Remodelação Vascular/fisiologia , Sistema Vasomotor/metabolismo , Sistema Vasomotor/fisiologia
3.
Int J Mol Sci ; 21(22)2020 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-33228032

RESUMO

It is well known that blood lipoproteins (LPs) are multimolecular complexes of lipids and proteins that play a crucial role in lipid transport. High-density lipoproteins (HDL) are a class of blood plasma LPs that mediate reverse cholesterol transport (RCT)-cholesterol transport from the peripheral tissues to the liver. Due to this ability to promote cholesterol uptake from cell membranes, HDL possess antiatherogenic properties. This function was first observed at the end of the 1970s to the beginning of the 1980s, resulting in high interest in this class of LPs. It was shown that HDL are the prevalent class of LPs in several types of living organisms (from fishes to monkeys) with high resistance to atherosclerosis and cardiovascular disorders. Lately, understanding of the mechanisms of the antiatherogenic properties of HDL has significantly expanded. Besides the contribution to RCT, HDL have been shown to modulate inflammatory processes, blood clotting, and vasomotor responses. These particles also possess antioxidant properties and contribute to immune reactions and intercellular signaling. Herein, we review data on the structure and mechanisms of the pleiotropic biological functions of HDL from the point of view of their evolutionary role and complex dynamic nature.


Assuntos
Aterosclerose/sangue , Colesterol/metabolismo , Homeostase/fisiologia , Lipoproteínas HDL/fisiologia , Animais , Anti-Infecciosos/sangue , Anti-Infecciosos/farmacologia , Anti-Inflamatórios/sangue , Anti-Inflamatórios/farmacologia , Antioxidantes/metabolismo , Antioxidantes/farmacologia , Aterosclerose/genética , Aterosclerose/fisiopatologia , Transporte Biológico , Coagulação Sanguínea/efeitos dos fármacos , Coagulação Sanguínea/fisiologia , Colesterol/química , Humanos , Lipoproteínas HDL/química , Lipoproteínas HDL/classificação , Lipoproteínas HDL/isolamento & purificação , Transdução de Sinais , Vasodilatadores/sangue , Vasodilatadores/farmacologia , Sistema Vasomotor/efeitos dos fármacos , Sistema Vasomotor/fisiologia
4.
Sci Rep ; 10(1): 10884, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616832

RESUMO

Peripheral hemodynamics, measured via the blood volume pulse and vasomotion, provide a valuable way of monitoring physiological state. Camera imaging-based systems can be used to measure these peripheral signals without contact with the body, at distances of multiple meters. While researchers have paid attention to non-contact imaging photoplethysmography, the study of peripheral hemodynamics and the effect of autonomic nervous system activity on these signals has received less attention. Using a method, based on a tissue-like model of the skin, we extract melanin [Formula: see text] and hemoglobin [Formula: see text] concentrations from videos of the hand and face and show that significant decreases in peripheral pulse signal power (by 36% ± 29%) and vasomotion signal power (by 50% ± 26%) occur during periods of cognitive and psychological stress. Via three experiments we show that similar results are achieved across different stimuli and regions of skin (face and hand). While changes in peripheral pulse and vasomotion power were significant the changes in pulse rate variability were less consistent across subjects and tasks.


Assuntos
Hemodinâmica , Fotopletismografia/métodos , Estresse Psicológico/diagnóstico por imagem , Pensamento , Estimulação Acústica , Adulto , Volume Sanguíneo , Conjuntos de Dados como Assunto , Face , Feminino , Dedos , Mãos , Frequência Cardíaca/fisiologia , Hemoglobinas/análise , Humanos , Masculino , Matemática , Melaninas/análise , Estimulação Luminosa , Estresse Psicológico/fisiopatologia , Sistema Vasomotor/fisiologia , Adulto Jovem
5.
Physiol Int ; 107(1): 134-144, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32491291

RESUMO

Microvascular function has been assessed by determining the rhythmic oscillations in blood flow induced by the vasomotion of resistance vessels. Although laser-Doppler flowmetry (LDF) allows simple, non-invasive evaluation of this flow-motion in the cutaneous microcirculation, the temporal and spatial reproducibility of such assessments remains unclear.In the present study, we investigated cutaneous flow-motion in three consecutive years in eight skin regions using LDF in six healthy young volunteers. The characteristic flow-motion frequency was determined using fast-Fourier transformation. Additionally, in two years a more traditional measure of microvascular reactivity, postocclusive reactive hyperemia (PORH) was evoked in the forearm after transient brachial artery occlusion (1-2-3 min) induced by cuff inflation.Well-defined flow-motion was found in six regions showing significant differences in frequency: the highest flow-motion frequency was found in the frontal and temporal regions (8.0 ± 1.1 and 8.5 ± 1.0 cycles/min, cpm, respectively, mean ± SD) followed by the scapular, infraclavicular and coxal regions (7.5 ± 1.3; 6.7 ± 1.1 and 6.5 ± 1.2 cpm, respectively). The lowest, stable flow-motion was found in the posterior femoral region (5.5 ± 1.0 cpm), whereas flow-motion was detectable only sporadically in the limbs. The region-dependent flow-motion frequencies were very stable within individuals either between the body sides, or among the three measurements, only the infraclavicular region showed a small difference (114 ± 17%∗, % of value in 1st year; ∗P < 0.05). However, PORH indices differed after 2-3 min occlusions significantly in consecutive years.We report that flow-motion frequencies determined from LDF signals show both region-specificity and excellent intra-individual temporal and spatial reproducibility suggesting their usefulness for non-invasive follow-up of microvascular reactivity.


Assuntos
Hiperemia , Microcirculação/fisiologia , Pele , Sistema Vasomotor/fisiologia , Adulto , Feminino , Antebraço/irrigação sanguínea , Antebraço/fisiologia , Voluntários Saudáveis , Humanos , Hiperemia/diagnóstico , Hiperemia/fisiopatologia , Fluxometria por Laser-Doppler/métodos , Masculino , Fluxo Sanguíneo Regional , Reprodutibilidade dos Testes , Pele/irrigação sanguínea , Pele/fisiopatologia
6.
Lipids Health Dis ; 19(1): 128, 2020 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-32505182

RESUMO

BACKGROUND: Inhalation of common air pollutants such as diesel and biodiesel combustion products can induce vascular changes in humans which may contribute to increased mortality and morbidity associated with fine particulate matter exposures. Diesel, biodiesel, and other combustion byproducts contain fatty acid components capable of entering the body through particulate matter inhalation. Fatty acids can also be endogenously released into circulation following a systemic stress response to some inhaled pollutants such as ozone. When in the circulation, bioactive fatty acids may interact with cells lining the blood vessels, potentially inducing endothelial dysfunction. To examine whether fatty acids could potentially be involved in human vascular responses to air pollutants, we determined the effects of fatty acids and derivatives on important vascular cell functions. METHODS: Human umbilical vein endothelial cells (HUVEC) were exposed in vitro to oleic acid (OA) or OA metabolites for 4-48 h. Cytotoxicity, vasodilator production (by ELISA measurement), mitochondrial function (using Sea Horse assays), and iron metabolism (inferred by ICP-OES measurements) were examined, with standard statistical testing (ANOVA, t-tests) employed. RESULTS: Dose-dependent cytotoxicity was noted at 24 h, with 12-hydroxy OA more potent than OA. Mitochondrial stress testing showed that 12-hydroxy OA and OA induce mitochondrial dysfunction. Analysis of soluble mediator release from HUVEC showed a dose-dependent increase in prostaglandin F2α, a lipid involved in control of vascular tone, at 24 h (85% above controls) after OA-BSA exposure. RT-PCR analysis revealed OA did not induce changes in gene expression at noncytotoxic concentrations in exposed HUVEC, but 12-OH OA did alter ICAM and COX2 gene expression. CONCLUSIONS: Together, these data demonstrate that FA may be capable of inducing cytotoxic effects and altering expression of mediators of vascular function following inhalation exposure, and may be implicated in air pollutant-induced deaths and hospitalizations. (267 of max 350 words).


Assuntos
Células Endoteliais da Veia Umbilical Humana/ultraestrutura , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/fisiologia , Ácido Oleico/toxicidade , Sistema Vasomotor/efeitos dos fármacos , Poluentes Atmosféricos/toxicidade , Ciclo-Oxigenase 2/genética , Dinoprosta/biossíntese , Expressão Gênica/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Células Endoteliais da Veia Umbilical Humana/fisiologia , Humanos , Molécula 1 de Adesão Intercelular/genética , Ferro/metabolismo , Ácidos Ricinoleicos/toxicidade , Sistema Vasomotor/fisiologia
7.
Am J Physiol Regul Integr Comp Physiol ; 318(1): R182-R187, 2020 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-31644318

RESUMO

Isocapnic hyperoxia (IH) evokes cerebral and peripheral hypoperfusion via both disturbance of redox homeostasis and reduction in nitric oxide (NO) bioavailability. However, it is not clear whether the magnitude of the vasomotor responses depends on the vessel network exposed to IH. To test the hypothesis that the magnitude of IH-induced reduction in peripheral blood flow (BF) may differ from the hypoperfusion response observed in the cerebral vascular network under oxygen-enriched conditions, nine healthy men (25 ± 3 yr, mean ± SD) underwent 10 min of IH during either saline or vitamin C (3 g) infusion, separately. Femoral artery (FA), internal carotid artery (ICA), and vertebral artery (VA) BF (Doppler ultrasound), as well as arterial oxidant (8-isoprostane), antioxidant [ascorbic acid (AA)], and NO bioavailability (nitrite) markers were simultaneously measured. IH increased 8-isoprostane levels and reduced nitrite levels; these responses were followed by a reduction in both FA BF and ICA BF, whereas VA BF did not change. Absolute and relative reductions in FA BF were greater than IH-induced changes in ICA and VA perfusion. Vitamin C infusion increased arterial AA levels and abolished the IH-induced increase in 8-isoprostane levels and reduction in nitrite levels. Whereas ICA and VA BF did not change during the vitamin C-IH trial, FA perfusion increased and reached similar levels to those observed during normoxia with saline infusion. Therefore, the magnitude of IH-induced reduction in femoral blood flow is greater than that observed in the vessel network of the brain, which might involve the determinant contribution that NO has in the regulation of peripheral vascular perfusion.


Assuntos
Artéria Carótida Interna/fisiologia , Circulação Cerebrovascular/fisiologia , Cérebro/irrigação sanguínea , Hiperóxia , Sistema Vasomotor/fisiologia , Adulto , Hemodinâmica , Humanos , Masculino , Fluxo Sanguíneo Regional , Artéria Vertebral/fisiologia , Adulto Jovem
8.
Climacteric ; 23(1): 46-52, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31269826

RESUMO

Purpose: This study aimed to prospectively determine the prevalence, duration, and severity of vasomotor symptoms (VMS) during menopause in a Chinese longitudinal cohort.Methods: This longitudinal cohort study recruited 187 participants from an urban Chinese community. The presence, frequency, degree, and duration of VMS were measured and analyzed.Results: A total of 83.4% of participating women experienced hot flashes and 82.9% reported night sweats, with nearly half reporting moderate to severe VMS (more than 3 times per day, or rated 4 or greater on a 1-8 severity scale). The median duration for both hot flashes and night sweats was 4.5 years. In a generalized linear mixed model, presence of VMS was significantly related to menopause stages, serum follicle stimulating hormone concentrations, general distress levels, and baseline body mass index.Discussion and conclusions: The prevalence of VMS in this longitudinal cohort was higher than that of previous Chinese cross-sectional studies and consistent with prior studies in western women. Meanwhile, the duration of symptomatic years in our study was shorter than that of western women. These results indicate that the difference in VMS between western and Chinese women appears to be in terms of the duration of symptoms, not prevalence.


Assuntos
Fogachos/epidemiologia , Menopausa/fisiologia , Sistema Vasomotor/fisiologia , China/epidemiologia , Feminino , Humanos , Estudos Longitudinais , Pessoa de Meia-Idade , Prevalência , Estudos Prospectivos , Sudorese
9.
Semin Reprod Med ; 37(3): 125-130, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31869840

RESUMO

Vasomotor symptoms, including hot flushes and night sweats, pose a significant symptomatic burden to women undergoing menopause, and negatively impact on both their physical and psychological well-being. Management of these symptoms can be challenging, with the use of conventional hormone replacement therapy limited by duration of treatment and clinical contraindications. Recent advances in our understanding of the neuroendocrine regulation of the reproductive axis and thermoregulation postmenopause has helped identify a promising new therapeutic target to ameliorate hot flushes. Antagonism of the neurokinin B/neurokinin-3 receptor (NK3R) signaling pathway has emerged as an efficacious treatment in managing vasomotor symptoms, with evidence of rapid and sustained reduction in hot flush frequency and severity and improvements in secondary quality-of-life measures such as sleep. Within this review, we will explore the growing body of evidence supporting the use of NK3R antagonists in the management of vasomotor symptoms, and the possible utility in managing dysfunctional sex-hormone-dependent disorders and glycolipid metabolism disorders such as polycystic ovarian syndrome.


Assuntos
Fogachos/etiologia , Fogachos/terapia , Menopausa/fisiologia , Neurocinina B/fisiologia , Receptores da Neurocinina-3/fisiologia , Feminino , Terapia de Reposição Hormonal/métodos , Humanos , Qualidade de Vida , Transdução de Sinais/fisiologia , Sistema Vasomotor/fisiologia , Sistema Vasomotor/fisiopatologia
10.
Neurogastroenterol Motil ; 31(12): e13709, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31452314

RESUMO

BACKGROUND: The rat has served usefully as a model for fecal incontinence and exploration of the mechanism of action of sacral neuromodulation. However, there is a gap in knowledge concerning representation(s) on the primary sensory cortex of this anatomical region. METHODS: Multi-electrode array (32 channels) and intrinsic optical signal (IOS) processing were used to map cortical activation sites following anorectal electrical stimulation in the rat. A simple method for expanding a 32-electrode array to a virtual 2700 array was refined. KEY RESULTS: The IOS method identified activation of parietal cortex following anorectal or first sacral nerve root (S1) stimulation; however, the signal was poorly localized and large spontaneous vasomotion was observed in pial vessels. In contrast, the resulting high-density maps showed two anatomically distinct cortical activation sites to anorectal stimulation. CONCLUSIONS & INFERENCES: There are two distinct sites of activation on the parietal cortex following anorectal stimulation in the rat. The implications for sacral neuromodulation as a therapy for fecal incontinence are discussed.


Assuntos
Canal Anal/inervação , Mapeamento Encefálico/métodos , Potenciais Somatossensoriais Evocados , Ratos/anatomia & histologia , Reto/inervação , Córtex Somatossensorial/fisiologia , Vias Aferentes/anatomia & histologia , Animais , Estimulação Elétrica , Eletrodos , Feminino , Pia-Máter/irrigação sanguínea , Ratos Wistar , Raízes Nervosas Espinhais/anatomia & histologia , Raízes Nervosas Espinhais/fisiologia , Sistema Vasomotor/anatomia & histologia , Sistema Vasomotor/fisiologia
11.
Pharmacol Ther ; 201: 120-136, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31153955

RESUMO

Based on work-done in the rostral ventrolateral medulla (RVLM), this review presents four lessons learnt from studying the differential impacts of oxidative stress and nitrosative stress on sympathetic vasomotor tone and their clinical and therapeutic implications. The first lesson is that an increase in sympathetic vasomotor tone because of augmented oxidative stress in the RVLM is responsible for the generation of neurogenic hypertension. On the other hand, a shift from oxidative stress to nitrosative stress in the RVLM underpins the succession of increase to decrease in sympathetic vasomotor tone during the progression towards brain stem death. The second lesson is that, by having different cellular sources, regulatory mechanisms on synthesis and degradation, kinetics of chemical reactions, and downstream signaling pathways, reactive oxygen species and reactive nitrogen species should not be regarded as a singular moiety. The third lesson is that well-defined differential roles of oxidative stress and nitrosative stress with distinct regulatory mechanisms in the RVLM during neurogenic hypertension and brain stem death clearly denote that they are not interchangeable phenomena with unified cellular actions. Special attention must be paid to their beneficial or detrimental roles under a specific disease or a particular time-window of that disease. The fourth lesson is that, to be successful, future antioxidant therapies against neurogenic hypertension must take into consideration the much more complicated picture than that presented in this review on the generation, maintenance, regulation or modulation of the sympathetic vasomotor tone. The identification that the progression towards brain stem death entails a shift from oxidative stress to nitrosative stress in the RVLM may open a new vista for therapeutic intervention to slow down this transition.


Assuntos
Estresse Nitrosativo/fisiologia , Estresse Oxidativo/fisiologia , Sistema Nervoso Simpático/fisiologia , Animais , Antioxidantes/farmacologia , Tronco Encefálico/fisiologia , Tronco Encefálico/fisiopatologia , Humanos , Hipertensão/fisiopatologia , Espécies Reativas de Nitrogênio/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Sistema Vasomotor/fisiologia
12.
Sci Rep ; 9(1): 186, 2019 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-30655574

RESUMO

Arterioles in the cutaneous microcirculation frequently display an oscillatory phenomenon defined vasomotion, consistent with periodic diameter variations in the micro-vessels associated with particular physiological or abnormal conditions. The cellular mechanisms underlying vasomotion and its physiological role have not been completely elucidated. Various mechanisms were demonstrated, based on cell Ca2+ oscillations determined by the activity of channels in the plasma membrane or sarcoplasmic reticulum of vascular cells. However, the possible engagement in vasomotion of cell metabolic oscillations of mitochondrial or glycolytic origin has been poorly explored. Metabolic oscillations associated with the production of ATP energy were previously described in cells, while limited studies have investigated these fluctuations in-vivo. Here, we characterised a low-frequency metabolic oscillator (MO-1) in skin from live wild-type and Nrf2-/- mice, by combination of fluorescence spectroscopy and wavelet transform processing technique. Furthermore, the relationships between metabolic and microvascular oscillators were examined during phenylephrine-induced vasoconstriction. We found a significant interaction between MO-1 and the endothelial EDHF vasomotor mechanism that was reduced in the presence of oxidative stress (Nrf2-/- mice). Our findings suggest indirectly that metabolic oscillations may be involved in the mechanisms underlying endothelium-mediated skin vasomotion, which might be altered in the presence of metabolic disturbance.


Assuntos
Estresse Oxidativo , Periodicidade , Pele/metabolismo , Sistema Vasomotor/fisiologia , Animais , Arteríolas/fisiologia , Fatores Biológicos/metabolismo , Metabolismo/fisiologia , Camundongos , Camundongos Knockout , Microcirculação/fisiologia , Fator 2 Relacionado a NF-E2/deficiência , Fator 2 Relacionado a NF-E2/genética , Fenilefrina/farmacologia , Pele/irrigação sanguínea , Vasoconstrição/efeitos dos fármacos
13.
Microvasc Res ; 121: 82-86, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30343001

RESUMO

This study examined cutaneous vasoconstriction to whole-body hypothermia, specifically contributions of neural and endothelial vasomotor responses in glabrous and non-glabrous skin. Eleven participants were semi-recumbent at an ambient temperature of 22 °C for 30 min, after which ambient temperature was decreased to 0 °C until rectal temperature (Tre) had decreased by 0.5 °C. Laser-Doppler fluxmetry was measured at the forehead and thigh for measures of glabrous and non-glabrous skin, respectively; wavelet analysis was performed on the laser-Doppler signal to determine endothelial and neural activities. Hypothermia took on average 97 ±â€¯7 min and caused marked decreases at glabrous (42 ±â€¯5%baseline, p < 0.001) and non-glabrous (69 ±â€¯4%baseline, p < 0.001) skin. In glabrous skin, neural activity increased from 11 ±â€¯1% at thermoneutral to 18 ±â€¯1% (p < 0.001). In non-glabrous skin there was an initial decrease (p = 0.001) in neural activity from 13 ±â€¯2% to 9 ±â€¯1% (-0.2 °C decrease in Tre) and then increased (p = 0.002) to 21 ±â€¯2% baseline at -0.5 °C Tre. Endothelial activity decreased in both glabrous (16 ±â€¯3% to 6 ±â€¯1%, p < 0.001) and non-glabrous (15 ±â€¯1% to 7 ±â€¯1%, p = 0.003) skin. Hypothermia elicits large decreases in skin blood flow in both glabrous and non-glabrous skin that are related to increases in neural activity and a reduction of endothelial activity.


Assuntos
Microcirculação , Microvasos/inervação , Pele/irrigação sanguínea , Vasoconstrição , Sistema Vasomotor/fisiologia , Adulto , Velocidade do Fluxo Sanguíneo , Humanos , Hipotermia Induzida , Fluxometria por Laser-Doppler , Masculino , Fluxo Sanguíneo Regional , Análise de Ondaletas , Adulto Jovem
14.
Acta Physiol (Oxf) ; 225(1): e13108, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29858558

RESUMO

Vascular endothelial cells, as well as smooth muscle cells, show heterogeneity with regard to their receptor expression and reactivity. For the vascular wall to act as a functional unit, the various cells' responses require integration. Such an integration is not only required for a homogeneous response of the vascular wall, but also for the vasomotor behaviour of consecutive segments of the microvascular arteriolar tree. As flow resistances of individual sections are connected in series, sections require synchronization and coordination to allow effective changes of conductivity and blood flow. A prerequisite for the local coordination of individual vascular cells and different sections of an arteriolar tree is intercellular communication. Connexins are involved in a dual manner in this coordination. (i) By forming gap junctions between cells, they allow an intercellular exchange of signalling molecules and electrical currents. In particular, the spread of electrical currents allows for coordination of cell responses over longer distances. (ii) Connexins are able to interact with other proteins to form signalling complexes. In this way, they can modulate and integrate individual cells' responses also in a channel-independent manner. This review outlines mechanisms allowing the vascular connexins to exert their coordinating function and to regulate the vasomotor reactions of blood vessels both locally, and in vascular networks. Wherever possible, we focus on the vasomotor behaviour of small vessels and arterioles which are the main vessels determining vascular resistance, blood pressure and local blood flow.


Assuntos
Conexinas/metabolismo , Células Endoteliais/fisiologia , Sistema Vasomotor/fisiologia , Conexinas/química , Conexinas/genética , Regulação da Expressão Gênica , Humanos
15.
Med Sci Sports Exerc ; 51(4): 653-662, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30489494

RESUMO

INTRODUCTION: The acute blood pressure (BP) decrease is greater after evening than morning exercise, suggesting that evening training (ET) may have a greater hypotensive effect. OBJECTIVE: This study aimed to compare the hypotensive effect of aerobic training performed in the morning versus evening in treated hypertensives. METHODS: Fifty treated hypertensive men were randomly allocated to three groups: morning training (MT), ET, and control (C). Training groups cycled for 45 min at moderate intensity (progressing from the heart rate of the anaerobic threshold to 10% below the heart rate of the respiratory compensation point), while C stretched for 30 min. Interventions were conducted 3 times per week for 10 wk. Clinic and ambulatory BP and hemodynamic and autonomic mechanisms were evaluated before and after the interventions. Clinic assessments were performed in the morning (7:00-9:00 AM) and evening (6:00-8:00 PM). Between-within ANOVA was used (P ≤ 0.05). RESULTS: Only ET decreased clinic systolic BP differently from C and MT (morning assessment -5 ± 6 mm Hg and evening assessment -8 ± 7 mm Hg, P < 0.05). Only ET reduced 24 h and asleep diastolic BP differently from C and MT (-3 ± 5 and -3 ± 4 mm Hg, respectively, P < 0.05). Systemic vascular resistance decreased from C only in ET (P = 0.03). Vasomotor sympathetic modulation decreased (P = 0.001) and baroreflex sensitivity (P < 0.02) increased from C in both training groups with greater changes in ET than MT. CONCLUSIONS: In treated hypertensive men, aerobic training performed in the evening decreased clinic and ambulatory BP due to reductions in systemic vascular resistance and vasomotor sympathetic modulation. Aerobic training conducted at both times of day increases baroreflex sensitivity, but with greater after ET.


Assuntos
Pressão Sanguínea/fisiologia , Exercício Físico/fisiologia , Hipertensão/fisiopatologia , Condicionamento Físico Humano , Adulto , Anti-Hipertensivos/uso terapêutico , Barorreflexo/fisiologia , Humanos , Hipertensão/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Fatores de Tempo , Resistência Vascular/fisiologia , Sistema Vasomotor/fisiologia
16.
PLoS One ; 13(9): e0203347, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30252845

RESUMO

Vasomotor response is related to the capacity of the vessel to maintain vascular tone within a narrow range. Two main control mechanisms are involved: the autonomic control of the sympathetic neural drive (global control) and the endothelial smooth cells capacity to respond to mechanical stress by releasing vasoactive factors (peripheral control). The aim of this study was to evaluate the effects of respiratory muscle training (RMT) on vasomotor response, assessed by flow-mediated dilation (FMD) and heart rate variability, in young healthy females. The hypothesis was that RMT could enhance the balance between sympathetic and parasympathetic neural drive and reduce vessel shear stress. Thus, twenty-four women were randomly assigned to either RMT or SHAM group. Maximal inspiratory mouth pressure and maximum voluntary ventilation were utilized to assess the effectiveness of the RMT program, which consisted of three sessions of isocapnic hyperventilation/ week for eight weeks, (twenty-four training sessions). Heart rate variability assessed autonomic balance, a global factor regulating the vasomotor response. Endothelial function was determined by measuring brachial artery vasodilation normalized by shear rate (%FMD/SR). After RMT, but not SHAM, maximal inspiratory mouth pressure and maximum voluntary ventilation increased significantly (+31% and +16%, respectively). Changes in heart rate variability were negligible in both groups. Only RMT exhibited a significant increase in %FMD/SR (+45%; p<0.05). These data suggest a positive effect of RMT on vasomotor response that may be due to a reduction in arterial shear stress, and not through modulation of sympatho-vagal balance.


Assuntos
Exercícios Respiratórios , Sistema Vasomotor/fisiologia , Adolescente , Adulto , Artéria Braquial/fisiologia , Exercícios Respiratórios/métodos , Feminino , Frequência Cardíaca/fisiologia , Humanos , Hiperemia/fisiopatologia , Hiperventilação/fisiopatologia , Ventilação Voluntária Máxima/fisiologia , Músculos Respiratórios/fisiologia , Vasodilatação/fisiologia , Adulto Jovem
17.
Basic Res Cardiol ; 113(5): 33, 2018 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-30073416

RESUMO

The local metabolic hypothesis proposes that myocardial oxygen tension determines the degree of autoregulation by increasing the production of vasodilator metabolites as perfusion pressure is reduced. Thus, normal physiologic levels of coronary venous PO2, an index of myocardial oxygenation, are proposed to be required for effective autoregulation. The present study challenged this hypothesis through determination of coronary responses to changes in coronary perfusion pressure (CPP 140-40 mmHg) in open-chest swine in the absence (n = 7) and presence of euvolemic hemodilution (~ 50% reduction in hematocrit), with (n = 5) and without (n = 6) infusion of dobutamine to augment MVO2. Coronary venous PO2 decreased over similar ranges (~ 28-15 mmHg) as CPP was lowered from 140 to 40 mmHg in each of the groups. However, coronary venous PO2 was not associated with changes in coronary blood flow (r = - 0.11; P = 0.29) or autoregulatory gain (r = - 0.29; P = 0.12). Coronary zero-flow pressure (Pzf) was measured in 20 mmHg increments and determined to be directly related to vascular resistance (r = 0.71; P < 0.001). Further analysis demonstrated that changes in coronary blood flow remained minimal at Pzf > 20 mmHg, but progressively increased as Pzf decreased below this threshold value (r = 0.68; P < 0.001). Coronary Pzf was also positively correlated with autoregulatory gain (r = 0.43; P = 0.001). These findings support that coronary autoregulatory behavior is predominantly dependent on an adequate degree of underlying vasomotor tone, independent of normal myocardial oxygen tension.


Assuntos
Circulação Coronária , Vasos Coronários/metabolismo , Hemodinâmica , Miocárdio/metabolismo , Oxigênio/sangue , Sistema Vasomotor/metabolismo , Agonistas de Receptores Adrenérgicos beta 1/farmacologia , Animais , Pressão Sanguínea , Circulação Coronária/efeitos dos fármacos , Vasos Coronários/efeitos dos fármacos , Dobutamina/farmacologia , Hemodiluição , Homeostase , Masculino , Modelos Animais , Transdução de Sinais , Sus scrofa , Vasodilatação , Sistema Vasomotor/fisiologia
18.
Gynecol Endocrinol ; 34(11): 913-919, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-29902942

RESUMO

Women during perimenopausal period experience a range of symptoms, which interfere with physical, sexual, and social life. About 65-75% of symptoms connected with postmenopausal period are vasomotor symptoms (VMS), such as hot flushes and night sweats. Hot flushes are subjective sensation of heat associated with cutaneous vasodilatation and drop in core temperature. It is suspected that VMS are strongly correlated with pulsatile oversecretion of gonadotropin-releasing hormone (GnRH) and subsequently luteinizing hormone (LH). Evidence has accumulated in parallel showing that lack of negative feedback of steroid hormones synthesized in ovary causes overactivation of hypertrophied kisspeptin/neurokinin B/dynorphin (KNDy) neurons, located in infundibular nucleus. Oversecretion of both kisspeptin (KISS1) and neurokinin B (NKB), as well as downregulation of dynorphin, plays dominant role in creation of GnRH pulses. This in turn causes VMS. Administration of senktide, highly potent and selective NK3R agonist, resulted in increase of serum LH concentration, induction of VMS, increase in heart rate, and skin temperature in postmenopausal women. These finding suggest that modulation of KNDy neurons may become new therapeutic approach in the treatment of VMS.


Assuntos
Fogachos/etiologia , Hipotálamo/fisiologia , Neurônios/fisiologia , Pós-Menopausa/fisiologia , Sistema Vasomotor/fisiologia , Dinorfinas/fisiologia , Retroalimentação Fisiológica , Feminino , Fogachos/tratamento farmacológico , Humanos , Kisspeptinas/fisiologia , Neurocinina B/fisiologia
19.
Am J Physiol Heart Circ Physiol ; 315(3): H602-H609, 2018 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-29906226

RESUMO

Current research indicates that vasomotor responses are altered with aging in skeletal muscle resistance arteries. The changes in vasomotor function are characterized by impaired vasodilator and vasoconstrictor responses. The detrimental effects of aging on vasomotor function are attenuated in some vascular beds after a program of endurance exercise training. The signals associated with exercise responsible for inducing improvements in vasomotor function have been proposed to involve short-duration increases in intraluminal shear stress and/or pressure during individual bouts of exercise. Here, we review evidence that increases in shear stress and pressure, within a range believed to present in these arteries during exercise, promote healthy vasomotor function in aged resistance arteries. We conclude that available research is consistent with the interpretation that short-duration mechanical stimulation, through increases in shear stress and pressure, contributes to the beneficial effects of exercise on vasomotor function in aged skeletal muscle resistance arteries.


Assuntos
Artérias/fisiologia , Exercício Físico , Músculo Esquelético/irrigação sanguínea , Sistema Vasomotor/fisiologia , Animais , Artérias/crescimento & desenvolvimento , Humanos , Mecanotransdução Celular , Músculo Esquelético/crescimento & desenvolvimento , Estresse Mecânico , Sistema Vasomotor/crescimento & desenvolvimento
20.
J Nutr ; 148(6): 844-850, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29878271

RESUMO

Background: The recycling of citrulline by argininosuccinate synthase 1 (ASS1) and argininosuccinate lyase (ASL) is crucial to maintain arginine availability and nitric oxide (NO) production. Pegylated arginine deiminase (ADI-PEG20) is a bacterial enzyme used to deplete circulating arginine. Objective: The goal of this research was to test the hypothesis that citrulline is able to sustain intracellular arginine availability for NO production in ADI-PEG20 arginine-depleted mice. Methods: Six- to 8-wk-old male C57BL/6J mice injected with ADI-PEG20 (5 IU) or saline (control) were used in 4 different studies. Arginine, citrulline, and NO kinetics were determined by using stable isotopes in unchallenged (study 1) and endotoxin-challenged (study 2) mice. Blood pressure was determined by telemetry for 6 d after ADI-PEG20 administration (study 3), and vasomotor activity and ASS1 and ASL gene expression were determined in mesenteric arteries collected from additional mice (study 4). Results: ADI-PEG20 administration resulted in arginine depletion (<1 compared with 111 ± 37 µmol/L) but in greater plasma citrulline concentrations (900 ± 123 compared with 76 ± 8 µmol/L; P < 0.001) and fluxes (402 ± 17 compared with 126 ± 4 µmol ⋅ kg-1 ⋅ h-1; P < 0.001) compared with controls. Endotoxin-challenged ADI-PEG20-treated mice produced less NO than controls (13 ± 1 compared with 27 ± 2 µmol ⋅ kg-1 ⋅ h-1; P < 0.001). No differences (P > 0.50) were observed for cardiovascular variables (heart rate, blood pressure) between ADI-PEG20-treated and control mice. Furthermore, no ex vivo vasomotor differences were observed between the 2 treatments. ADI-PEG20 administration resulted in greater gene expression of ASS1 (∼3-fold) but lower expression of ASL (-30%). Conclusion: ADI-PEG20 successfully depleted circulating arginine without any effect on cardiovascular endpoints in healthy mice but limited NO production after endotoxin challenge. Therefore, the citrulline recycling pathway can sustain local arginine availability independently from circulating arginine, satisfying the demand of arginine for endothelial NO production; however, it is unable to do so when a high demand for arginine is elicited by endotoxin.


Assuntos
Arginina/deficiência , Citrulina/metabolismo , Endotoxinas/toxicidade , Óxido Nítrico/metabolismo , Animais , Argininossuccinato Sintase , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Hidrolases , Marcação por Isótopo , Masculino , Redes e Vias Metabólicas , Camundongos , Camundongos Endogâmicos C57BL , Polietilenoglicóis , Sistema Vasomotor/efeitos dos fármacos , Sistema Vasomotor/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...