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1.
Neurology ; 97(2): e136-e144, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-33947784

RESUMO

OBJECTIVE: To describe the natural history of afferent baroreflex failure (ABF) based on systematic review of clinical and laboratory data in patients with a diagnosis of ABF at Mayo Clinic Rochester. METHODS: We performed a retrospective chart review of all patients who underwent standardized autonomic reflex testing between 2000 and 2020 and had confirmation of the diagnosis of ABF by an autonomic disorders specialist. Patients were identified using a data repository of medical records. Variables included demographic, all-cause mortality, medications, ABF manifestations, comorbidities, and laboratory (autonomic testing, blood pressure monitoring, echocardiogram, brain imaging, plasma catecholamines, serum sodium level, and kidney function tests). RESULTS: A total of 104 patients with ABF were identified. Head and neck radiation was the most common etiology (86.5%), followed by neck surgery (5.8%) and other causes (7.7%). The most common findings were hypertension (87.5%), fluctuating blood pressure (78.8%), orthostatic hypotension (91.3%), syncope (58.6%), headache (22.1%), and tachycardia (20.2%). Patients commonly received antihypertensives (66.3%), pressor agents (41.3%), or a combination of both (19.2%). The median latency from completion of radiation to ABF was longer compared to the latency in the surgery group (p < 0.0001). Comorbidities, including complications from neck radiation, were frequently seen and all-cause mortality was 39.4% over a 20-year period. CONCLUSIONS: ABF should be suspected in patients with prior head and neck cancer treated by radiation or surgery who present with labile hypertension and orthostatic hypotension. Management may require both antihypertensive and pressor medications. The morbidity and mortality in ABF are high.


Assuntos
Doenças do Sistema Nervoso Autônomo/fisiopatologia , Barorreflexo/fisiologia , Vias Aferentes/fisiopatologia , Doenças do Sistema Nervoso Autônomo/complicações , Pressão Sanguínea/fisiologia , Determinação da Pressão Arterial , Humanos , Hipertensão/complicações , Estudos Retrospectivos
2.
Front Immunol ; 12: 637845, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33995355

RESUMO

Baroreflex and chemoreflex act through the autonomic nervous system, which is involved with the neural regulation of inflammation. The present study reports the effects of reflex physiological sympathetic activation in endotoxemic rats using bilateral carotid occlusion (BCO), a physiological approach involving the baroreflex and chemoreflex mechanisms and the influence of the baroreceptors and peripheral chemoreceptors in the cardiovascular and systemic inflammatory responses. After lipopolysaccharide (LPS) administration, the arterial pressure was recorded during 360 min in unanesthetized rats, and serial blood samples were collected to analyze the plasma cytokine levels. BCO elicited the reflex activation of the sympathetic nervous system, providing the following outcomes: (I) increased the power of the low-frequency band in the spectrum of the systolic arterial pressure during the BCO period; (II) reduced the levels of pro-inflammatory cytokines in plasma, including the tumor necrosis factor (TNF) and the interleukin (IL)-1ß; (III) increased the plasma levels of anti-inflammatory cytokine IL-10, 90 min after LPS administration. Moreover, selective baroreceptor or chemoreceptor denervation deactivated mechanosensitive and chemical sensors, respectively, and decreased the release of the LPS-induced cytokine but did not alter the BCO modulatory effects. These results show, for the first time, that physiological reflex activation of the sympathetic circuit decreases the inflammatory response in endotoxemic rats and suggest a novel function for the baroreceptors as immunosensors during the systemic inflammation.


Assuntos
Barorreflexo/fisiologia , Endotoxemia/patologia , Inflamação/fisiopatologia , Pressorreceptores/fisiologia , Sistema Nervoso Simpático/fisiologia , Animais , Sistema Nervoso Autônomo/fisiologia , Pressão Sanguínea/fisiologia , Células Quimiorreceptoras/fisiologia , Interleucina-10/sangue , Interleucina-1beta/sangue , Lipopolissacarídeos , Ratos , Ratos Wistar , Fator de Necrose Tumoral alfa/sangue
3.
Clin Neurophysiol ; 132(7): 1537-1542, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34023631

RESUMO

OBJECTIVE: Changes in baroreflex sensitivity have been reported in patients with idiopathic Parkinson's disease (PD). We sought to investigate the hypothesis that patients with isolated rapid eye movement (REM)-sleep behavior disorder (iRBD), known to be a prodromal stage for PD, will show abnormalities in baroreflex control. METHODS: Ten iRBD patients were compared to 10 sex- and age-matched healthy controls. Their cardiovascular parameters and muscle sympathetic nerve activity (MSNA) were evaluated at rest and during baroreflex stimulation. RESULTS: MSNA at rest was higher in iRBD patients (burst frequency [BF]: 44 ± 3 bursts/min; burst incidence [BI]: 60 ± 8 bursts/100 heartbeats) as compared to the controls (BF: 29 ± 3 bursts/min, p < 0.001; BI: 43 ± 9 bursts/100 heartbeats, p < 0.001). During baroreflex stimulation, iRBD patients showed increased absolute values of MSNA (BF: F = 62.728; p < 0.001; BI: F = 16.277; p < 0.001) as compared to the controls. The iRBD patients had decreased diastolic blood pressure at baseline and during lower body negative pressure, but the level of significance was not met. CONCLUSION: Our study shows increased MSNA and impaired baroreflex control in iRBD patients. We propose that the inhibitory effect of locus coeruleus on baroreflex function might be impaired, leading to the disinhibition of sympathetic outflow. SIGNIFICANCE: These findings might reflect the destruction of brain areas due to the ascending P-α-synuclein deposits in iRBD patients.


Assuntos
Fibras Adrenérgicas/fisiologia , Barorreflexo/fisiologia , Músculo Esquelético/inervação , Músculo Esquelético/fisiopatologia , Transtorno do Comportamento do Sono REM/diagnóstico , Transtorno do Comportamento do Sono REM/fisiopatologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia/métodos
4.
Am J Physiol Regul Integr Comp Physiol ; 321(1): R62-R78, 2021 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-33978481

RESUMO

Obese Zucker rats (OZRs) develop hypertension and hyperinsulinemia by 3 mo of age. Male OZRs also have diminished baroreflex-mediated activation of nucleus tractus solitarius (NTS) and bradycardia, which are improved by correcting their hyperglycemia. Conversely, 3-mo-old female OZRs and lean Zucker rats (LZRs) have equivalent baroreflex-mediated bradycardia that is impaired in 6-mo-old OZRs. We hypothesized that 3-mo-old female OZRs maintain NTS activation and baroreflexes coincident with glycemic control. We also hypothesized that 6-mo-old female OZRs develop impaired baroreflexes with hyperglycemia and diminished NTS activation. In 12- to 16-wk-old females, sympathetic nerve activity (SNA) and arterial pressure (AP) were higher in OZRs than LZRs. However, baroreflex-mediated inhibition of SNA and bradycardia were equivalent in female OZRs and LZRs. Unlike deficits in male OZRs, female OZRs and LZRs had no differences in phenylephrine-induced c-Fos expression in NTS or decreases in SNA and AP evoked by glutamate into NTS. Compared with hyperglycemia in male OZRs (217.9 ± 34.4 mg/dL), female OZRs had normal fed blood glucose levels (108.2 ± 1.6 mg/dL in LZRs and 113.6 ± 3.5 mg/dL in OZRs) with emerging glucose intolerance. Conscious 24- to 27-wk-old female OZRs had impaired baroreflex-mediated bradycardia, but fed blood glucose was modestly elevated (124.2 ± 5.2 mg/dL) and phenylephrine-induced c-Fos expression in NTS was comparable to LZRs. These data suggest that better glycemic control in 3-mo-old female OZRs prevents diminished NTS activation and baroreflexes, supporting the notion that hyperglycemia impairs these responses in male OZRs. However, 6-mo-old female OZRs had impaired baroreflex efficacy without diminished NTS activation or pronounced hyperglycemia, suggesting baroreflex deficits develop by different mechanisms in female and male OZRs.


Assuntos
Barorreflexo/fisiologia , Glicemia/metabolismo , Controle Glicêmico , Hipertensão , Obesidade , Envelhecimento , Animais , Colesterol/sangue , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Hiperinsulinismo , Insulina/sangue , Masculino , Fenilefrina/farmacologia , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Zucker , Fatores Sexuais , Sistema Nervoso Simpático , Triglicerídeos/sangue
5.
Life Sci ; 277: 119498, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-33864817

RESUMO

AIMS: To evaluate the systemic changes and autonomic cardiocirculatory control of awaken rats chronically exposed to the cigarette smoke (CS) of 1 or 2 cigarettes/day. MAIN METHODS: Rats were exposed to clean air (control) or cigarette smoke of 1 (CS1) or 2 (CS2) cigarettes/animal/day for 30 days. Then, arterial pressure (AP) and heart rate (HR) were recorded in conscious rats to assess spontaneous baroreflex sensitivity and HR and AP variabilities. Evoked baroreflex and cardiac autonomic tone were evaluated by vasoactive drugs and autonomic blockers, respectively. In another group, ventilatory and cardiovascular parameters were recorded under hypoxia and hypercapnia stimulus. At the end of protocols, heart, lung, kidneys and liver were collected for histological analysis. KEY FINDINGS: Rats exposed to CS showed morphological changes, being more evident in the CS2 group. Also, less weight gain and cardiac hypertrophy were prominent in CS2 rats. Basal AP and HR, spontaneous baroreflex sensitivity and cardiovascular variabilities were similar among groups. CS exposure progressively blunted the bradycardia response to phenylephrine (-2.2 ± 0.1 vs. -1.7 ± 0.2 vs. -1.5 ± 0.2) while the tachycardia response to sodium nitroprusside was slightly increased compared to control. Vagal tone was not affected by CS, but CS2 rats exhibited higher sympathetic tone (-25 ± 4 vs. -28 ± 4 vs. -56 ± 9) and lower intrinsic HR (411 ± 4 vs. 420 ± 8 vs. 390 ± 6). Exposure to CS of 2 cigarettes also exacerbated the reflex cardiovascular and ventilatory responses to hypoxia and hypercapnia. SIGNIFICANCE: CS exposure for 30 days promoted systemic changes and autonomic cardiocirculatory dysfunction in rats depending on the daily exposure dose.


Assuntos
Sistema Nervoso Autônomo/efeitos dos fármacos , Sistema Cardiovascular/efeitos dos fármacos , Fumar Cigarros/efeitos adversos , Animais , Sistema Nervoso Autônomo/fisiopatologia , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Bradicardia/fisiopatologia , Sistema Cardiovascular/fisiopatologia , Relação Dose-Resposta a Droga , Coração/fisiopatologia , Frequência Cardíaca/fisiologia , Masculino , Ratos , Ratos Wistar , Reflexo , Taquicardia/fisiopatologia , Nervo Vago/fisiopatologia
6.
J Vis Exp ; (168)2021 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-33645573

RESUMO

Blood pressure (BP) and heart rate (HR) are both controlled by the autonomic nervous system (ANS) and are closely intertwined due to reflex mechanisms. The baroreflex is a key homeostatic mechanism to counteract acute, short-term changes in arterial BP and to maintain BP in a relatively narrow physiological range. BP is sensed by baroreceptors located in the aortic arch and carotid sinus. When BP changes, signals are transmitted to the central nervous system and are then communicated to the parasympathetic and sympathetic branches of the autonomic nervous system to adjust HR. A rise in BP causes a reflex decrease in HR, a drop in BP causes a reflex increase in HR. Baroreflex sensitivity (BRS) is the quantitative relationship between changes in arterial BP and corresponding changes in HR. Cardiovascular diseases are often associated with impaired baroreflex function. In various studies reduced BRS has been reported in e.g., heart failure, myocardial infarction, or coronary artery disease. Determination of BRS requires information from both BP and HR, which can be recorded simultaneously using telemetric devices. The surgical procedure is described beginning with the insertion of the pressure sensor into the left carotid artery and positioning of its tip in the aortic arch to monitor arterial pressure followed by the subcutaneous placement of the transmitter and ECG electrodes. We also describe postoperative intensive care and analgesic management. After a two-week period of post-surgery recovery long-term ECG and BP recordings are performed in conscious and unrestrained mice. Finally, we include examples of high-quality recordings and the analysis of spontaneous baroreceptor sensitivity using the sequence method.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Estado de Consciência/fisiologia , Eletrocardiografia , Telemetria , Animais , Artérias Carótidas/fisiologia , Ritmo Circadiano/fisiologia , Eletrodos Implantados , Frequência Cardíaca/fisiologia , Humanos , Masculino , Camundongos Endogâmicos C57BL , Processamento de Sinais Assistido por Computador , Software
7.
PLoS One ; 16(3): e0247576, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33661958

RESUMO

Blood pressure regulation following spinal cord injury (SCI) is often compromised due to impaired vascular sympathetic control, leading to increased reliance on cardiovagal baroreflex sensitivity to maintain pressure. Whole-body exercise improves cardiovagal baroreflex sensitivity in uninjured individuals, though has not been explored in those with SCI. Our objective was to determine changes in cardiovagal baroreflex sensitivity following 6 months of high-intensity, whole-body exercise in individuals with SCI compared to lower-intensity, arms only exercise, or waitlist. This randomized controlled trial recruited individuals with SCI aged 18-40 years old. Sixty-one individuals were randomized, with 38 completing at least one cardiovagal baroreflex sensitivity assessment. Whole-body exercise was performed with hybrid functional electrical stimulation rowing prescribed as two to three times per week, for 30-60 minutes with a target heart rate of >75% of maximum. The arms only exercise group performed upper body rowing exercise with the same prescription as whole-body exercise. Waitlist controls were not enrolled in any explicit training regimen. After 6 months, those in arms only exercise or waitlist crossed over to whole-body exercise. Cardiovagal baroreflex sensitivity was assessed via the neck suction technique at baseline and at three-month intervals thereafter. Intention to treat analysis with a structured equation model demonstrated no significant effect of waitlist control or arms only exercise on cardiovagal baroreflex sensitivity. Whole-body exercise significantly improved cardiovagal baroreflex sensitivity at 6 months for those initially randomized (p = 0.03), as well as those who crossed over from arms only exercise or waitlist control (p = 0.03 for each). However, amount of exercise performed and aerobic gains (VO2max) each poorly correlated with increases in cardiovagal baroreflex sensitivity (R2<0.15). In post-hoc analyses, individuals with paraplegia made significantly greater gains in baroreflex sensitivity compared to those with tetraplegia (p = 0.02), though gains within this group were again poorly correlated to gains in aerobic capacity. Clinicaltrials.gov number NCT02139436.


Assuntos
Pressão Sanguínea/fisiologia , Terapia por Exercício/métodos , Exercício Físico/fisiologia , Traumatismos da Medula Espinal/terapia , Adolescente , Adulto , Barorreflexo/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Avaliação de Resultados em Cuidados de Saúde , Consumo de Oxigênio/fisiologia , Estudos Prospectivos , Traumatismos da Medula Espinal/fisiopatologia , Fatores de Tempo , Adulto Jovem
8.
PLoS One ; 16(3): e0248428, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33735286

RESUMO

BACKGROUND: The increase of blood pressure (BP) variability (BPV) is recognized as an important additional cardiovascular risk factor in both normotensive subjects and hypertensive patients. Aging-induced atherosclerosis and autonomic dysfunction impair the baroreflex and, in turn, augment 24-hour BPV. In small and large animal experiments, impaired baroreflex steepens the slope of the power spectrum density (PSD) of continuous BP in the frequency range of 0.01 to 0.1 Hz. Although the repeated oscillometric BP recording over 24 hours or longer is a prerequisite to quantify BPV in humans, how the very short-term continuous BP recording reflects BPV remains unknown. This study aimed to evaluate the impact of aging on the very short-term (30-min) BPV in healthy human subjects by frequency analysis. METHODS: We recorded continuous BP tonometrically for 30 min in 56 healthy subjects aged between 28 and 85 years. Considering the frequency-dependence of the baroreflex dynamic function, we estimated the PSD of BP in the frequency range of 0.01 to 0.1 Hz, and compared the characteristics of PSD among four age groups (26-40, 41-55, 56-70 and 71-85 years). RESULTS: Aging did not significantly alter mean and standard deviation (SD) of BP among four age groups. PSD was nearly flat around 0.01 Hz and decreased gradually as the frequency increased. The slope of PSD between 0.01 and 0.1 Hz was steeper in older subjects (71 years or older) than in younger subjects (55 years or younger) (p < 0.05). CONCLUSIONS: Aging steepened the slope of PSD of BP between 0.01 and 0.1 Hz. This phenomenon may partly be related to the deterioration of the baroreflex in older subjects. Our proposed method to evaluate very short-term continuous BP recordings may contribute to the stratification of BPV.


Assuntos
Envelhecimento/fisiologia , Variação Biológica Individual , Pressão Sanguínea/fisiologia , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Barorreflexo/fisiologia , Determinação da Pressão Arterial/métodos , Determinação da Pressão Arterial/estatística & dados numéricos , Feminino , Voluntários Saudáveis , Fatores de Risco de Doenças Cardíacas , Humanos , Masculino , Manometria/métodos , Manometria/estatística & dados numéricos , Pessoa de Meia-Idade
9.
J Neurophysiol ; 125(4): 1425-1439, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33625931

RESUMO

The incidence of Parkinson's disease (PD) is increasing worldwide. Although the PD hallmark is the motor impairments, nonmotor dysfunctions are now becoming more recognized. Recently, studies have suggested that baroreflex dysfunction is one of the underlying mechanisms of cardiovascular dysregulation observed in patients with PD. However, the large body of literature on baroreflex function in PD is unclear. The baroreflex system plays a major role in the autonomic, and ultimately blood pressure and heart rate, adjustments that accompany acute cardiovascular stressors on a daily basis. Therefore, impaired baroreflex function (i.e., decreased sensitivity or gain) can lead to altered neural cardiovascular responses. Since PD affects parasympathetic and sympathetic branches of the autonomic nervous system and both are orchestrated by the baroreflex system, understanding of this crucial mechanism in PD is necessary. In the present review, we summarize the potential altered central and peripheral mechanisms affecting the feedback-controlled loops that comprise the reflex arc in patients with PD. Major factors including arterial stiffness, reduced number of C1 and activation of non-C1 neurons, presence of central α-synuclein aggregation, cardiac sympathetic denervation, attenuated muscle sympathetic nerve activity, and lower norepinephrine release could compromise baroreflex function in PD. Results from patients with PD and from animal models of PD provide the reader with a clearer picture of baroreflex function in this clinical condition. By doing so, our intent is to stimulate future studies to evaluate several unanswered questions in this research area.


Assuntos
Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Bulbo/fisiopatologia , Doença de Parkinson/fisiopatologia , Sistema Nervoso Simpático/fisiopatologia , Animais , Humanos , Bulbo/metabolismo , Bulbo/patologia
10.
Clin Exp Hypertens ; 43(4): 356-362, 2021 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-33567918

RESUMO

Purpose: Decreased baroreflex sensitivity (BRS) and sympathovagal imbalance (SVI) have been reported as a cardiovascular (CV) risk in gestational hypertension (GH). Nitric oxide (NO) has been implicated in pathophysiology of GH. In the present study, we assessed the link of CV risks (decreased BRS and SVI) to the plasma levels of NO in women having risk of developing GH. Materials and Methods: A total of 96 pregnant women having risk factors for GH were recruited for the study. The blood pressure variability (BPV), heart rate variability (HRV), plasma NO, marker of insulin resistance (HOMA-IR), lipid risk factors, inflammatory markers (hsCRP, interleukin-6), and malondialdehyde (MDA), the marker of oxidative stress (OS) were measured at 16th and 36th week. Link of various parameters to NO was assessed by correlation and multiple regression analysis. Results: Of HRV indices, parasympathetic components were decreased and sympathetic components were increased, BRS was decreased, NO was decreased, HOMA-IR, lipid risk factors, hsCRP, interleukin-6, and MDA were increased significantly at 36th week compared to 16th week of pregnancy. Most of the markers of cardiometabolic risk were correlated with NO. However, only the markers of CV risk (SVI and reduced BRS) were independently associated with decreased level of NO, but not the metabolic markers except interleukin-6. The independent contribution of BRS (ß = 0.334, P < .001) to NO was found to be most significant. Conclusion: It was concluded that decreased BRS, SVI, and increased interleukin-6 are associated with reduction in NO in GH, which may possibly be linked to the development of CV risks in GH.


Assuntos
Barorreflexo/fisiologia , Frequência Cardíaca/fisiologia , Hipertensão Induzida pela Gravidez/fisiopatologia , Óxido Nítrico/metabolismo , Adulto , Biomarcadores/sangue , Pressão Sanguínea , Índice de Massa Corporal , Peso Corporal , Feminino , Humanos , Hipertensão Induzida pela Gravidez/sangue , Mediadores da Inflamação/metabolismo , Interleucina-6 , Lipídeos/sangue , Masculino , Análise Multivariada , Estresse Oxidativo , Gravidez , Análise de Regressão , Fatores de Risco , Adulto Jovem
11.
Open Heart ; 8(1)2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33563778

RESUMO

OBJECTIVE: In the last years, a debate exists about type, intensity and frequency of physical exercise that is really indicated to protect healthy subjects from cardiovascular disease. Regular physical training has been associated with an improved cardiovascular risk profile, but it has also been demonstrated that strenuous and uncontrolled physical exercise could be dangerous, in terms of increased cardiovascular morbidity and mortality. In the present study, we evaluated a group of 35 amateur half-marathon runners, who were likewise studied 10 years before (B). The results of B suggested that an increased cardiac sympathetic modulation could potentially represent a negative prognostic factor. The aim of this follow-up was to assess the medium-long-term effects of moderate to vigorous physical training on the cardiovascular neural control, cardiac function and occurrence of cardiovascular diseases. METHODS: Each enrolled subject underwent: (1) an interview and physical examination to ascertain the presence of cardiovascular disease; (2) standing test to evaluate the cardiovascular neural control by means of heart rate variability (HRV), arterial blood pressure (AP) variability and baroreflex sensitivity (BRS); (3) transthoracic echocardiography to evaluate cardiac function. RESULTS: At 10-year follow-up (FU), in this group of middle-aged athletes the occurrence of cardiovascular diseases was low, not unlike that of the overall population. The results of HRV analysis showed a decreased sympathetic and increased vagal modulation directed to the heart, compared with B. In addition, HRV, AP variability and BRS indices showed a physiological response to active standing. Finally, athletes had normal echocardiographic measures. CONCLUSION: We conclude that in our group of athletes a regular moderate-vigorous physical training through the 10 years was quite beneficial as the prevalence of sympathetic cardiac modulation observed at B was not accompanied by increased cardiovascular risk, on the contrary a slight prevalence of vagal indices was observed at FU.


Assuntos
Atletas , Pressão Sanguínea/fisiologia , Exercício Físico/fisiologia , Previsões , Frequência Cardíaca/fisiologia , Corrida de Maratona/fisiologia , Sistema Nervoso/fisiopatologia , Adulto , Idoso , Barorreflexo/fisiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade
13.
J Exp Zool A Ecol Integr Physiol ; 335(3): 348-358, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33503334

RESUMO

The most commonly used technique to study the barostatic regulation of blood pressure in ectothermic vertebrates consists of determining the heart rate response to pharmacological manipulations of blood pressure, the so-called "Oxford method." Although well established, the Oxford method has some important limitations, such as induction of hypervolemia in small animals and undesired effects of vasoactive drugs on central and peripheral baroreflex components. As an alternative, the sequence method, which consists in the computerized evaluation of naturally-occurring baroreflex adjustments of heart rate without the need for pharmacological administrations, was developed to study baroreflexes. In the present study, we compare this sequence method with the Oxford technique in two teleost species with different life styles, and we assess the optimal software configuration for the employment of the sequence method in fish. Calculation of baroreflex gain through the sequence method was adequate and reliable when the software was configured to search for baroreflex sequences with a minimum length of three cardiac cycles with a delay of one cardiac cycle between fluctuations in mean ventral aortic blood pressure and reflex changes in pulse interval. When properly configured, the sequence and the Oxford methods yielded similar determinations of the baroreflex gain in fish.


Assuntos
Barorreflexo/fisiologia , Determinação da Pressão Arterial/veterinária , Pressão Sanguínea/fisiologia , Caraciformes , Tilápia , Animais , Determinação da Pressão Arterial/métodos
14.
Circ Heart Fail ; 14(1): e007448, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33464953

RESUMO

BACKGROUND: Continuous-flow (CF) left ventricular assist devices (LVADs) improve outcomes for patients with advanced heart failure (HF). However, the lack of a physiological pulse predisposes to side-effects including uncontrolled blood pressure (BP), and there are little data regarding the impact of CF-LVADs on BP regulation. METHODS: Twelve patients (10 males, 60±11 years) with advanced heart failure completed hemodynamic assessment 2.7±4.1 months before, and 4.3±1.3 months following CF-LVAD implantation. Heart rate and systolic BP via arterial catheterization were monitored during Valsalva maneuver, spontaneous breathing, and a 0.05 Hz repetitive squat-stand maneuver to characterize cardiac baroreceptor sensitivity. Plasma norepinephrine levels were assessed during head-up tilt at supine, 30o and 60o. Heart rate and BP were monitored during cardiopulmonary exercise testing. RESULTS: Cardiac baroreceptor sensitivity, determined by Valsalva as well as Fourier transformation and transfer function gain of Heart rate and systolic BP during spontaneous breathing and squat-stand maneuver, was impaired before and following LVAD implantation. Norepinephrine levels were markedly elevated pre-LVAD and improved-but remained elevated post-LVAD (supine norepinephrine pre-LVAD versus post-LVAD: 654±437 versus 323±164 pg/mL). BP increased during cardiopulmonary exercise testing post-LVAD, but the magnitude of change was modest and comparable to the changes observed during the pre-LVAD cardiopulmonary exercise testing. CONCLUSIONS: Among patients with advanced heart failure with reduced ejection fraction, CF-LVAD implantation is associated with modest improvements in autonomic tone, but persistent reductions in cardiac baroreceptor sensitivity. Exercise-induced increases in BP are blunted. These findings shed new light on mechanisms for adverse events such as stroke, and persistent reductions in functional capacity, among patients supported by CF-LVADs. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03078972.


Assuntos
Barorreflexo/fisiologia , Insuficiência Cardíaca/terapia , Coração Auxiliar , Pressorreceptores/fisiopatologia , Idoso , Pressão Sanguínea/fisiologia , Teste de Esforço , Feminino , Insuficiência Cardíaca/fisiopatologia , Frequência Cardíaca/fisiologia , Hemodinâmica , Humanos , Masculino , Pessoa de Meia-Idade , Norepinefrina/sangue , Manobra de Valsalva/fisiologia
15.
Eur J Appl Physiol ; 121(2): 539-547, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33151437

RESUMO

PURPOSE: We analysed the characteristics of arterial baroreflexes during the first phase of apnoea (φ1). METHODS: 12 divers performed rest and exercise (30 W) apnoeas (air and oxygen). We measured beat-by-beat R-to-R interval (RRi) and mean arterial pressure (MAP). Mean RRi and MAP values defined the operating point (OP) before (PRE-ss) and in the second phase (φ2) of apnoea. Baroreflex sensitivity (BRS, ms·mmHg-1) was calculated with the sequence method. RESULTS: In PRE-ss, BRS was (median [IQR]): at rest, 20.3 [10.0-28.6] in air and 18.8 [13.8-25.2] in O2; at exercise 9.2[8.4-13.2] in air and 10.1[8.4-13.6] in O2. In φ1, during MAP decrease, BRS was lower than in PRE-ss at rest (6.6 [5.3-11.4] in air and 7.7 [4.9-14.3] in O2, p < 0.05). At exercise, BRS in φ1 was 6.4 [3.9-13.1] in air and 6.7 [4.1-9.5] in O2. After attainment of minimum MAP (MAPmin), baroreflex resetting started. After attainment of minimum RRi, baroreflex sequences reappeared. In φ2, BRS at rest was 12.1 [9.6-16.2] in air, 12.9 [9.2-15.8] in O2. At exercise (no φ2 in air), it was 7.9 [5.4-10.7] in O2. In φ2, OP acts at higher MAP values. CONCLUSION: In apnoea φ1, there is a sudden correction of MAP fall via baroreflex. The lower BRS in the earliest φ1 suggests a possible parasympathetic mechanism underpinning this reduction. After MAPmin, baroreflex resets, displacing its OP at higher MAP level; thus, resetting may not be due to central command. After resetting, restoration of BRS suggests re-establishment of vagal drive.


Assuntos
Apneia/fisiopatologia , Barorreflexo/fisiologia , Exercício Físico/fisiologia , Descanso/fisiologia , Adulto , Apneia/metabolismo , Pressão Sanguínea/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Oxigênio/metabolismo , Nervo Vago/metabolismo , Nervo Vago/fisiologia
16.
Acta Pharmacol Sin ; 42(6): 898-908, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33154555

RESUMO

Hydrogen sulfide (H2S), which is closely related to various cardiovascular disorders, lowers blood pressure (BP), but whether this action is mediated via the modification of baroreflex afferent function has not been elucidated. Therefore, the current study aimed to investigate the role of the baroreflex afferent pathway in H2S-mediated autonomic control of BP regulation. The results showed that baroreflex sensitivity (BRS) was increased by acute intravenous NaHS (a H2S donor) administration to renovascular hypertensive (RVH) and control rats. Molecular expression data also showed that the expression levels of critical enzymes related to H2S were aberrantly downregulated in the nodose ganglion (NG) and nucleus tractus solitarius (NTS) in RVH rats. A clear reduction in BP by the microinjection of NaHS or L-cysteine into the NG was confirmed in both RVH and control rats, and a less dramatic effect was observed in model rats. Furthermore, the beneficial effects of NaHS administered by chronic intraperitoneal infusion on dysregulated systolic blood pressure (SBP), cardiac parameters, and BRS were verified in RVH rats. Moreover, the increase in BRS was attributed to activation and upregulation of the ATP-sensitive potassium (KATP) channels Kir6.2 and SUR1, which are functionally expressed in the NG and NTS. In summary, H2S plays a crucial role in the autonomic control of BP regulation by improving baroreflex afferent function due at least in part to increased KATP channel expression in the baroreflex afferent pathway under physiological and hypertensive conditions.


Assuntos
Vias Aferentes/metabolismo , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Sulfeto de Hidrogênio/metabolismo , Hipertensão/fisiopatologia , Animais , Anti-Hipertensivos/farmacologia , Barorreflexo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Cardiotônicos/farmacologia , Cistationina beta-Sintase/metabolismo , Cistationina gama-Liase/metabolismo , Sulfeto de Hidrogênio/farmacologia , Hipertensão/tratamento farmacológico , Masculino , Gânglio Nodoso/efeitos dos fármacos , Gânglio Nodoso/enzimologia , Gânglio Nodoso/metabolismo , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Ratos Sprague-Dawley , Núcleo Solitário/efeitos dos fármacos , Núcleo Solitário/enzimologia , Núcleo Solitário/metabolismo , Sulfetos/farmacologia , Receptores de Sulfonilureias/metabolismo , Sulfurtransferases/metabolismo
17.
Clin Exp Hypertens ; 43(2): 112-119, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-32896167

RESUMO

OBJECTIVE: We studied the link of decreased baroreflex sensitivity (BRS) to cardiometabolic risks and prehypertension status in postmenopausal women during their early menopausal phase. METHODS: Premenopausal women (n = 55) and early-postmenopausal women (n = 50) of age group between 40 and 55 years were recruited for the study, and their anthropometric parameters, complete battery of autonomic function tests (AFT), BRS, hormone levels, and cardiometabolic risk parameters were measured and compared between two groups. Correlation analysis of BRS with various physiological and biochemical parameters in these two groups were performed. Multiple regression analysis of BRS with various other associated factors in postmenopausal subjects and bivariate logistic regression analysis for assessing prediction of prehypertension status by BRS in postmenopausal group were performed. RESULTS: There was a significant difference in AFT and metabolic parameters between premenopausal and postmenopausal women. Sympathovagal imbalance (increased sympathetic and decreased parasympathetic) was prominent in early-postmenopausal women. Decreased BRS, the marker of cardiovascular (CV) risk was found to be significant (P < .001) and correlated with various cardiometabolic parameters in early-postmenopausal subjects. Multiple regression analysis demonstrated that decreased BRS is independently linked to parameters of decreased vagal activity, inflammation, and oxidative stress in early-postmenopausal group. Decreased BRS could predict prehypertension status in early-postmenopausal subjects as confirmed by bivariate logistic regression analysis. CONCLUSION: Sympathovagal imbalance, decreased BRS and considerable metabolic derangements were observed in women in their early phase of menopause. Decreased BRS appears to be associated with the cardiometabolic risks in these women. Prehypertension status in early-postmenopausal subjects could be predicted by decreased BRS.


Assuntos
Barorreflexo/fisiologia , Pós-Menopausa/fisiologia , Pré-Hipertensão , Biomarcadores/sangue , Pressão Sanguínea/fisiologia , Fatores de Risco Cardiometabólico , Feminino , Frequência Cardíaca/fisiologia , Humanos , Inflamação/fisiopatologia , Pessoa de Meia-Idade , Estresse Oxidativo , Pré-Hipertensão/diagnóstico , Pré-Hipertensão/metabolismo , Pré-Hipertensão/fisiopatologia , Nervo Vago/fisiopatologia
18.
Med Sci Sports Exerc ; 53(3): 606-612, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32804901

RESUMO

INTRODUCTION: Individuals with intellectual disability (ID) have an increased risk of cardiovascular disease and reduced work capacity, which could partly be explained by alterations to autonomic and hemodynamic regulation. The measurement of heart rate and blood pressure during isometric handgrip (HG) exercise, a sympathoexcitatory stimulus, is a noninvasive method to investigate autonomic and hemodynamic alterations. The purpose of this study was to assess alterations to autonomic and associated hemodynamic regulation between individuals with ID and a matched control group during isometric HG exercise. METHODS: Individuals with ID (n = 13; 31 ± 2 yr, 27.6 ± 7.7 kg·m-2) and without ID (n = 16; 29 ± 7 yr, 24.2 ± 2.8 kg·m-2) performed 2 min of isometric HG exercise at 30% of maximal voluntary contraction (MVC) in the seated position. Blood pressure was averaged for 2 min before, during, and after HG exercise (mean arterial pressure [MAP], systolic blood pressure, and diastolic blood pressure). Heart rate variability, blood pressure variability, and baroreflex sensitivity were calculated from the continuous blood pressure and heart rate recordings. RESULTS: Isometric HG elicited a blunted response in systolic blood pressure, diastolic blood pressure, and MAP among individuals with ID compared with individuals without ID, even after controlling for strength (MAP: rest, HG, recovery; ID: 103 ± 7, 108 ± 9, 103 ± 7; without ID: 102 ± 7, 116 ± 10, 104 ± 10 mm Hg; interaction P < 0.05). Individuals with ID also had an attenuated baroreflex sensitivity response to HG exercise compared with individuals without ID (interaction P = 0.041), but these effects were no longer significant after controlling for maximal voluntary contraction. Indices of heart rate variability and blood pressure variability were not different between groups overall or in response to HG exercise (P > 0.05). CONCLUSIONS: Individuals with ID have a blunted hemodynamic and autonomic response to isometric HG exercise compared with individuals without ID.


Assuntos
Sistema Nervoso Autônomo/fisiopatologia , Exercício Físico/fisiologia , Força da Mão/fisiologia , Hemodinâmica/fisiologia , Deficiência Intelectual/fisiopatologia , Adulto , Barorreflexo/fisiologia , Pressão Sanguínea/fisiologia , Estudos de Casos e Controles , Diástole/fisiologia , Feminino , Frequência Cardíaca/fisiologia , Humanos , Masculino , Sístole/fisiologia , Adulto Jovem
19.
Life Sci ; 267: 118972, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33383052

RESUMO

Cisplatin treatment induces an autonomic dysfunction and gastrointestinal and cardiovascular disorders. Physical exercise as well as pyridostigmine treatment induces improves in the autonomic nervous system. In the current study, we investigated the effect of physical exercise and pyridostigmine treatment on gastrointestinal and cardiovascular changes in cisplatin-treated rats. Rats were divided into groups: Saline (S), Cisplatin (Cis), Exercise (Ex), Cisplatin+Exercise (Cis+Ex), Pyridostigmine (Pyr), and Cisplatin+Pyridostigmine (Cis+Pyr). We induced gastrointestinal dysmotility by administering 3 mg kg-1 of cisplatin once week for 5 weeks. The Ex was swimming (1 h per day/5 days per week for 5 weeks with 5% b.w.). GE was evaluated through the colorimetric method of fractional red phenol recovery 10 min after feeding. Pyr groups received 1.5 mg kg-1, p.o. or concomitant Cis treatment. Moreover, gastric contraction in vitro and hemodynamic parameters such as MAP, HR, and evoked baroreflex sensitivity were assessed, as well as sympathetic and parasympathetic tone and intrinsic heart rate (IHR). Cis decrease GE vs. saline (p<0.05). Cis+Ex or Cis+Pyr prevented (p<0.05) decrease in GE vs. Cis rats. Cis decreased (p<0.05) gastric responsiveness in vitro vs. saline. Cis+Ex or Cis+Pyr prevented this phenomenon. Cis treatment increase MAP and decrease in HR (p<0.05) vs saline. Cis+Ex or Cis+Pyr attenuated (p<0.05) both alterations. Cis increased sympathetic tone and decreased vagal tone and IHR (p<0.05) vs. the saline. Cis+Ex or Cis+Pyr prevented those effects vs. the Cis group. In conclusion, physical exercise and pyridostigmine treatment improves autonomic dysfunction and prevented GE delay and changes in hemodynamic parameters, baroreflex sensitivity, and cardiac autonomic control in cisplatin-treated rats.


Assuntos
Barorreflexo/efeitos dos fármacos , Condicionamento Físico Animal/fisiologia , Brometo de Piridostigmina/farmacologia , Animais , Sistema Nervoso Autônomo/fisiopatologia , Barorreflexo/fisiologia , Pressão Sanguínea/efeitos dos fármacos , Pressão Sanguínea/fisiologia , Sistema Cardiovascular/fisiopatologia , Cisplatino/efeitos adversos , Cisplatino/farmacologia , Esvaziamento Gástrico/efeitos dos fármacos , Esvaziamento Gástrico/fisiologia , Coração/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Masculino , Infarto do Miocárdio/fisiopatologia , Ratos , Ratos Wistar , Nervo Vago/efeitos dos fármacos
20.
Hypertension ; 77(1): 147-157, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33296248

RESUMO

Central infusion of Ang II (angiotensin II) has been associated with increased sympathetic outflow resulting in neurogenic hypertension. In the present study, we appraised whether the chronic increase in central Ang II activates the paraventricular nucleus of the hypothalamus (PVN) resulting in elevated sympathetic tone and altered baro- and chemoreflexes. Further, we evaluated the contribution of HIF-1α (hypoxia-inducible factor-1α), a transcription factor involved in enhancing the expression of N-methyl-D-aspartate receptors and thus glutamatergic-mediated sympathetic tone from the PVN. Ang II infusion (20 ng/minute, intracerebroventricular, 14 days) increased mean arterial pressure (126±9 versus 84±4 mm Hg), cardiac sympathetic tone (96±7 versus 75±6 bpm), and decreased cardiac parasympathetic tone (16±2 versus 36±3 versus bpm) compared with saline-infused controls in conscious rats. The Ang II-infused group also showed an impaired baroreflex control of heart rate (-1.50±0.1 versus -2.50±0.3 bpm/mm Hg), potentiation of the chemoreflex pressor response (53±7 versus 30±7 mm Hg) and increased number of FosB-labeled cells (53±3 versus 19±4) in the PVN. Concomitant with the activation of the PVN, there was an increased expression of HIF-1α and N-Methyl-D-Aspartate-type1 receptors in the PVN. Further, Ang II-infusion showed increased renal sympathetic nerve activity (20.5±2.3% versus 6.4±1.9% of Max) and 3-fold enhanced renal sympathetic nerve activity responses to microinjection of N-methyl-D-aspartate (200 pmol) into the PVN of anesthetized rats. Further, silencing of HIF-1α in NG108 cells abrogated the expression of N-methyl-D-aspartate-N-methyl-D-aspartate-type1 induced by Ang II. Taken together, our studies suggest a novel Ang II-HIF-1α-N-methyl-D-aspartate receptor-mediated activation of preautonomic neurons in the PVN, resulting in increased sympathetic outflow and alterations in baro- and chemoreflexes.


Assuntos
Angiotensina II/farmacologia , Ácido Glutâmico/fisiologia , Subunidade alfa do Fator 1 Induzível por Hipóxia/fisiologia , Núcleo Hipotalâmico Paraventricular/efeitos dos fármacos , Sistema Nervoso Simpático/efeitos dos fármacos , Animais , Barorreflexo/efeitos dos fármacos , Barorreflexo/fisiologia , Hipertensão/fisiopatologia , Rim/inervação , Masculino , N-Metilaspartato/farmacologia , Núcleo Hipotalâmico Paraventricular/fisiologia , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/fisiologia , Sistema Nervoso Simpático/fisiologia
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