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 JovemRESUMO
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/fisiologiaRESUMO
BACKGROUND: Obesity is associated with increased risk for stroke. The breath-holding index (BHI) is a measure of vasomotor reactivity of the brain which can be measured with the transcranial Doppler (TCD). We aim to evaluate obesity as an independent factor for altered cerebrovascular reactivity. METHODS: Cerebrovascular hemodynamics (mean flow velocities MFV, pulsatility index, PI, resistance index, RI, and BHI) was determined in 85 non-obese (Body Mass Index, BMI ≤27 kg/m2) and 85 obese subjects (BMI ≥35 kg/m2) without diabetes mellitus and hypertension. Anthropometric and metabolic variables, and scores to detect risk for obstructive sleep apnea (OSA) were analyzed for their association with the cerebrovascular reactivity. RESULTS: The BHI was significantly lower in subjects with obesity according to BMI and in subjects with abdominal obesity, but the PI and RI were not different between groups. There was a linear association between the BMI, the HOMA-IR, the Matsuda index, the waist circumference, and the neck circumference, with the cerebrovascular reactivity. After adjusting for insulin resistance, neck circumference, and abdominal circumference, obesity according to BMI was negatively correlated with the cerebrovascular reactivity. CONCLUSIONS: We found a diminished vasomotor reactivity in individuals with obesity which was not explained by the presence of insulin resistance.
Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Índice de Massa Corporal , Transtornos Cerebrovasculares/fisiopatologia , Resistência à Insulina/fisiologia , Obesidade/fisiopatologia , Sistema Vasomotor/fisiologia , Adulto , Estudos de Casos e Controles , Transtornos Cerebrovasculares/diagnóstico , Transtornos Cerebrovasculares/epidemiologia , Estudos Transversais , Feminino , Humanos , Masculino , Obesidade/diagnóstico , Obesidade/epidemiologia , Fatores de Risco , Apneia Obstrutiva do Sono/diagnóstico , Apneia Obstrutiva do Sono/epidemiologia , Apneia Obstrutiva do Sono/fisiopatologia , Circunferência da Cintura/fisiologiaRESUMO
OBJECTIVE: To examine the relationship between climate (including altitude, temperature, humidity and annual range of temperature) and experience of hot flushes and night sweats amongst Spanish-speaking mid-aged women living in five urban centers. METHODS: A total of 896 peri- and postmenopausal women from centers in Chile (Santiago de Chile), Ecuador (Guayaquil and Quito), Panama (Panama City) and Spain (Madrid) completed questionnaires eliciting information about sociodemographics, hot flushes (prevalence, frequency and problem-rating), health and lifestyle (body mass index, diet, exercise, alcohol use) and mood (Women's Health Questionnaire). RESULTS: There was a wide range of altitude and temperature in the participating centers. Of the sample, 58.5% (524/896) were currently experiencing vasomotor symptoms. Prevalence was associated with higher temperatures, while hot flushes were more frequent and problematic for women living in higher temperature and lower altitudes. Hot flush variables were not associated with seasonal variation in temperature. When health and lifestyle variables were included as covariates in regression analyses, prevalence was best predicted by age (younger), poor general health, more depressed mood and anxiety; hot flush frequency by anxiety, temperature, life satisfaction (lower), age (higher), regular strenuous exercise (more strenuous exercise more frequent), and a diet including regular hot spicy food intake. Hot flush problem-rating was best predicted by anxiety, life satisfaction, altitude (lower more problematic), any regular exercise (more exercise less problematic), and depressed mood. CONCLUSIONS: In this study of Spanish-speaking women, those living in countries with higher temperatures and lower altitudes reported more frequent and problematic hot flushes.
Assuntos
Altitude , Clima , Fogachos/epidemiologia , Hiperidrose/epidemiologia , Perimenopausa/fisiologia , Pós-Menopausa/fisiologia , Temperatura , Fatores Etários , Análise de Variância , Distribuição de Qui-Quadrado , Chile , Intervalos de Confiança , Equador , Exercício Físico , Feminino , Alimentos , Humanos , Idioma , Pessoa de Meia-Idade , Razão de Chances , Panamá , Perimenopausa/psicologia , Pós-Menopausa/psicologia , Prevalência , Espanha , População Urbana , Sistema Vasomotor/fisiologiaRESUMO
The aim of the present work is to describe the integration of a mathematical model for the baroreceptor reflex mechanism to provide regulatory action into a dimensionally heterogeneous (3D-1D-0D) closed-loop model of the cardiovascular system. Such heterogeneous model comprises a 1D description of the arterial tree, a 0D network for the venous, cardiac and pulmonary circulations and 3D patient-specific geometries for vascular districts of interest. Thus, the detailed topological description of the arterial network allows us to perform vasomotor control actions in a differentiated way, while gaining insight about the effects of the baroreflex regulation over hemodynamic quantities of interest throughout the entire network. Two examples of application are presented. Firstly, we simulate the hemorrhage in the abdominal aorta artery and analyze the action of the baroreflex over the system. Secondly, the self-regulated closed-loop model is applied to study the influence of the control action in the hemodynamic environment that determines the blood flow pattern in a cerebral aneurism in the presence of a regurgitating aortic valve.
Assuntos
Barorreflexo/fisiologia , Hemostasia/fisiologia , Modelos Cardiovasculares , Aorta Abdominal/lesões , Pressão Sanguínea/fisiologia , Volume Sanguíneo/fisiologia , Hemorragia/fisiopatologia , Humanos , Sistema Vasomotor/fisiologia , Função Ventricular Esquerda/fisiologiaRESUMO
Several cardiovascular diseases (CVD) observed in adulthood have been associated with environmental influences during fetal growth. Here, we show that maternal exposure to cadmium, a ubiquitously distributed heavy metal and main component of cigarette smoke is able to induce cardiovascular morpho-functional changes in the offspring at adult age. Heart morphology and vascular reactivity were evaluated in the adult offspring of rats exposed to 30ppm of cadmium during pregnancy. Echocardiographic examination shows altered heart morphology characterized by a concentric left ventricular hypertrophy. Also, we observed a reduced endothelium-dependent reactivity in isolated aortic rings of adult offspring, while endothelium-independent reactivity remained unaltered. These effects were associated with an increase of hem-oxygenase 1 (HO-1) expression in the aortas of adult offspring. The expression of HO-1 was higher in females than males, a finding likely related to the sex-dependent expression of the vascular cell adhesion molecule 1 (VCAM-1), which was lower in the adult female. All these long-term consequences were observed along with normal birth weights and absence of detectable levels of cadmium in fetal and adult tissues of the offspring. In placental tissues however, cadmium levels were detected and correlated with increased NF-κB expression--a transcription factor sensitive to inflammation and oxidative stress--suggesting a placentary mechanism that affect genes related to the development of the cardiovascular system. Our results provide, for the first time, direct experimental evidence supporting that exposure to cadmium during pregnancy reprograms cardiovascular development of the offspring which in turn may conduce to a long term increased risk of CVD.
Assuntos
Cádmio/toxicidade , Exposição Materna/efeitos adversos , Efeitos Tardios da Exposição Pré-Natal/induzido quimicamente , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Sistema Vasomotor/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/fisiologia , Cádmio/administração & dosagem , Feminino , Masculino , Gravidez , Ratos , Ratos Wistar , Sistema Vasomotor/fisiologiaRESUMO
Extracellular nucleotides transmit signals into the cells through the P2 family of cell surface receptors. These receptors are amply expressed in human blood vessels and participate in vascular tone control; however, their signaling mechanisms remain unknown. Here we show that in smooth muscle cells of isolated human chorionic arteries, the activation of the P2Y(2) receptor (P2Y(2)R) induces not only its partition into membrane rafts but also its rapid internalization. Cholesterol depletion with methyl-beta-cyclodextrin reduced the association of the agonist-activated receptor into membrane rafts but did not affect either the UTP-mediated vasoconstrictions or the vasomotor responses elicited by both serotonin and KCl. Ex vivo perfusion of human chorionic artery segments with 1-10 mum UTP, a selective P2Y(2)R agonist, displaced the P2Y(2)R localization into membrane rafts within 1 min, a process preceded by the activation of both RhoA and Rac1 GTPases. AG1478, a selective and potent inhibitor of the epidermal growth factor receptor tyrosine kinase activity, not only blocked the UTP-induced vasomotor activity but also abrogated both RhoA and Rac1 activation, the P2Y(2)R association with membrane rafts, and its internalization. Altogether, these results show for the first time that the plasma membrane distribution of the P2Y(2)R is transregulated by the epidermal growth factor receptor, revealing an unsuspected functional interplay that controls both the membrane distribution and the vasomotor activity of the P2Y(2)R in intact human blood vessels.
Assuntos
Córion/irrigação sanguínea , Receptores ErbB/metabolismo , Regulação da Expressão Gênica , Receptores Purinérgicos P2/biossíntese , Uridina Trifosfato/metabolismo , Actinas/química , Artérias/metabolismo , Feminino , Humanos , Ligantes , Microdomínios da Membrana/metabolismo , Placenta/metabolismo , Gravidez , Receptores Purinérgicos P2/química , Receptores Purinérgicos P2Y2 , Transdução de Sinais , Uridina Trifosfato/química , Sistema Vasomotor/fisiologiaRESUMO
Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.
Assuntos
Pressão Sanguínea/fisiologia , Hipertensão/fisiopatologia , Bulbo/fisiologia , Sistema Nervoso Simpático/fisiologia , Sistema Vasomotor/fisiologia , Animais , Barorreflexo/fisiologia , Humanos , RatosRESUMO
Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.
Numerosas formas de evidência experimental obtidas nos últimos 37 anos demonstraram inequivocamente que a medula oblongata contém os principais circuitos responsáveis pela geração e manutenção do tono vasomotor e a regulação da pressão arterial. A visão atual que possuímos destes circuitos deriva em grande parte dos estudos de Pedro Guertzenstein, um estudante e mais tarde Professor de Fisiologia da UNIFESP e seus colaboradores. Nesta revisão nós sumarizamos os seus principais resultados assim como a nossa colaboração para uma melhor compreensão da regulação da pressão arterial em condições normais e patológicas.
Assuntos
Animais , Humanos , Ratos , Pressão Sanguínea/fisiologia , Hipertensão/fisiopatologia , Bulbo/fisiologia , Sistema Nervoso Simpático/fisiologia , Sistema Vasomotor/fisiologia , Barorreflexo/fisiologiaRESUMO
INTRODUCTION: Systolic blood pressure (SBP) is still measured in rats by the tail-cuff method, allowing readings when pulse/flow disappears during cuff inflation and reappears during deflation, separated by a compression interval. Although cuff deflation is habitually used to estimate SBP, we found cuff deflation-cuff inflation pressure to be usually negative, indicating that cuff deflation pressure < cuff inflation pressure. METHODS: SBP was measured in 226 male Wistar and SHR utilizing compression intervals of different durations, and also pharmacological interventions intended to modulate the cuff deflation-cuff inflation cycle. Direct, simultaneous intravascular measurements were also performed in some animals. RESULTS AND DISCUSSION: With compression interval congruent with 15 s, cuff deflation-cuff inflation was--6 +/- 0.6 mmHg in 73 Wistar and--6 +/- 1.4 mmHg in 51 SHR. Lengthening compression interval up to 4 min increased cuff deflation-cuff inflation pressure significantly to--27 +/- 3 mmHg in Wistar and to - 31 +/- 5 mmHg in SHR, suggesting accumulation of a vasodilating mediator. This increase of cuff deflation-cuff inflation pressure was prevented by papaverine (totally in Wistar, partially in SHR), indicating its dependence on vasodilatory capacity. Adrenergic blockade decreased cuff deflation-cuff inflation pressure to--13 +/- 5 mmHg (P < 0.05) in SHR, but had no effect in Wistar rats. Injection of L-NAME decreased cuff deflation-cuff inflation pressure to--5 +/- 2 mmHg (P < 0.05) in Wistar rats but was ineffective in SHR. Simultaneous measurements by tail-cuff method and carotid cannulation revealed that the cuff inflation most accurately estimated the intravascular SBP. CONCLUSIONS: 1) Cuff inflation measurements should be considered representative of SBP, as cuff deflation can underestimate SBP depending on compression interval duration, 2) nitric oxide accumulation due to flow deprivation is the main cause of SBP underestimation by cuff deflation in Wistar, and 3) in SHR, nitric oxide effects were minimal, and sympathetic activation plus physical factors seemed to predominate in the determining the outcome of measurements.