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Motohisa Osaka
There are some reports that sympathetic nerve activity (SNA) shows a characteristic pattern a few hours before the onset of lethal ventricular arrhythmias. If so, it could be possible to predict sudden cardiac death a few hours in advance of its occurrence. Recently, we reported that a previously unidentified V-trough of SNA is a potential precursor of lethal cardiac events by examining 24-hour ambulatory electrocardiograms in which such an event was recorded by chance. In contrast, the chaotic nature of heart rate variability has been noted recently from the viewpoint of nonlinear dynamics...
2018: Journal of Nippon Medical School, Nippon Ika Daigaku Zasshi
Mamoru Tanida, Zhang Tao, Lingling Sun, Jie Song, Wei Yang, Yuichi Kuda, Yasutaka Kurata, Toshishige Shibamoto
NEW FINDINGS: What is the central question of this study? Whether anaphylaxis affects sympathetic outflows to the brown adipose tissue (BAT) and adrenal grand is not known. Moreover, it is unknown whether anaphylaxis affects some brain areas in association with sympathetic regulation. What is the main finding and its importance? We showed that sympathoexcitatory responses to anaphylaxis regionally occurred in the kidney and adrenal grand, but not in the thermogenesis-related BAT. Further, anaphylactic hypotension also caused increase in c-fos immunoreactivity in the hypothalamic and medullary areas...
March 10, 2018: Experimental Physiology
Jason R Carter, Daniela Grimaldi, Ida T Fonkoue, Lisa Medalie, Babak Mokhlesi, Eve Van Cauter
Study Objectives: Chronic insomnia affects up to 15% of adults. Recent cross-sectional and prospective epidemiological studies report an association between insomnia and hypertension, including incident hypertension, yet mechanisms underlying the association remain unknown. We hypothesized that subjects with chronic insomnia would have elevated sympathetic neural outflow, blunted baroreflex sensitivity, and augmented sympathetic neural and cardiovascular reactivity to stress when compared to good-sleeper controls...
March 7, 2018: Sleep
Marcus Granegger, Martin Schweiger, Marianne Schmid Daners, Mirko Meboldt, Michael Hübler
PURPOSE: Rotary blood pumps are a promising treatment approach for patients with a total cavopulmonary connection and a failing cardiovascular system. The aim of this study was to investigate the hemodynamic effects of cavopulmonary support using a numerical model with closed-loop baroreflex and exercise mechanisms. METHODS: A numerical model of the univentricular cardiovascular system was developed, mimicking the hemodynamics during rest and exercise. Rotary blood pumps with different hydraulic pump characteristics (flat vs steep pressure-flow relationships) were investigated in the cavopulmonary position...
March 1, 2018: International Journal of Artificial Organs
Milene R Malheiros-Lima, Washington Pires, Ivana A T Fonseca, Julliane V Joviano-Santos, Anderson J Ferreira, Cândido C Coimbra, Nilo R V Lima, Samuel P Wanner
This study aimed to investigate the chronic effects of caudal artery denervation on morphometric parameters of the tail vascular smooth muscle and on physical exercise-induced thermoregulatory and cardiovascular adjustments in rats. Male Wistar rats were subjected to caudal artery denervation or the sham procedure. Approximately 26-28 days after these procedures, their thermoregulatory and cardiovascular parameters were evaluated at rest and during or following a fatiguing treadmill run. At the end of the experiments, the rats were euthanized, and samples of their tails were removed to evaluate morphometric parameters of the vascular smooth muscle surrounding the caudal artery...
2018: Frontiers in Physiology
Daisuke Matsutani, Masaya Sakamoto, Hiroyuki Iuchi, Souichirou Minato, Hirofumi Suzuki, Yosuke Kayama, Norihiko Takeda, Ryuzo Horiuchi, Kazunori Utsunomiya
BACKGROUND: It is presently unclear whether glycemic variability (GV) is associated with baroreflex sensitivity (BRS), which is an early indicator of cardiovascular autonomic neuropathy. The present study is the first to examine the relationships between BRS and GV measured using continuous glucose monitoring (CGM). METHODS: This was a multicenter, prospective, open-label clinical trial. A total of 102 patients with type 2 diabetes were consecutively recruited for this study...
March 7, 2018: Cardiovascular Diabetology
Hiromi Yamamoto, Toru Kawada, Shuji Shimizu, Kazunori Uemura, Masashi Inagaki, Kazuyoshi Kakehi, Yoshitaka Iwanaga, Kanji Fukuda, Tadayoshi Miyamoto, Shunichi Miyazaki, Masaru Sugimachi
AIMS: To assess the acute effects of intravenous ivabradine, a selective bradycardic agent, on carotid sinus baroreflex-mediated sympathetic arterial pressure (AP) and heart rate (HR) responses. METHODS AND RESULTS: In anesthetized and vagotomized Wistar-Kyoto rats (n=6), carotid sinus baroreceptor regions were isolated. Changes in splanchnic sympathetic nerve activity (SNA), AP, and HR in response to a step-wise pressure input were examined before and after intravenous ivabradine (2mg/kg)...
April 15, 2018: International Journal of Cardiology
Catherine L Tegeler, Lee Gerdes, Hossam A Shaltout, Jared F Cook, Sean L Simpson, Sung W Lee, Charles H Tegeler
BACKGROUND: Military-related post-traumatic stress (PTS) is associated with numerous symptom clusters and diminished autonomic cardiovascular regulation. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) is a noninvasive, closed-loop, allostatic, acoustic stimulation neurotechnology that produces real-time translation of dominant brain frequencies into audible tones of variable pitch and timing to support the auto-calibration of neural oscillations. We report clinical, autonomic, and functional effects after the use of HIRREM® for symptoms of military-related PTS...
December 22, 2017: Military Medical Research
Daniel Canuto, Kwitae Chong, Cayley Bowles, Erik P Dutson, Jeff D Eldredge, Peyman Benharash
A computational tool is developed for simulating the dynamic response of the human cardiovascular system to various stressors and injuries. The tool couples zero-dimensional models of the heart, pulmonary vasculature, and peripheral vasculature to one-dimensional models of the major systemic arteries. To simulate autonomic response, this multiscale circulatory model is integrated with a feedback model of the baroreflex, allowing control of heart rate, cardiac contractility, and peripheral impedance. The performance of the tool is demonstrated in two scenarios: neurogenic hypertension by sustained stimulation of the sympathetic nervous system, and an acute 10 percent hemorrhage from the left femoral artery...
March 2, 2018: International Journal for Numerical Methods in Biomedical Engineering
Sushmita Purkayastha, Kaitlyn Maffuid, Xiaojie Zhu, Rong Zhang, Peter B Raven
PURPOSE: This preliminary study tested the hypothesis that the carotid baroreflex (CBR) mediated sympathoexcitation regulates cerebral blood flow (CBF) at rest and during dynamic exercise. METHODS: In seven healthy subjects (26 ± 1 years), oscillatory neck pressure (NP) stimuli of + 40 mmHg were applied to the carotid baroreceptors at a pre-determined frequency of 0.1 Hz at rest, low (10 ± 1W), and heavy (30 ± 3W) exercise workloads (WLs) without (control) and with α - 1 adrenoreceptor blockade (prazosin)...
March 1, 2018: European Journal of Applied Physiology
Takuya Kishi
Heart failure is defined as a disruption of circulatory homeostasis. We have demonstrated that baroreflex dysfunction strikingly disrupts circulatory homeostasis. Moreover, previous many reports have suggested that central excess oxidative stress causes sympathoexcitation in heart failure. However, the central mechanisms of baroreflex dysfunction with oxidative stress has not been fully clarified. Our hypothesis was that the impairment of central antioxidant property would worsen circulatory homeostasis with baroreflex dysfunction in heart failure...
February 25, 2018: International Journal of Molecular Sciences
Jacqueline K Limberg, Elizabeth P Ott, Walter W Holbein, Sarah Elizabeth Baker, Timothy B Curry, Wayne T Nicholson, Michael J Joyner, J Kevin Shoemaker
To study how changes in baroreceptor afferent activity affect patterns of sympathetic neural activation, we manipulated arterial blood pressure using intravenous nitroprusside (NTP) and phenylephrine (PE) and measured action potential (AP) patterns with wavelet-based methodology. We hypothesized: 1) Baroreflex unloading (NTP) would increase firing of low-threshold axons and recruitment of latent axons, and 2) Baroreflex loading (PE) would decrease firing of low-threshold axons. Heart rate (HR, ECG), arterial blood pressure (BP, brachial catheter), and muscle sympathetic nerve activity (MSNA, microneurography of the peroneal nerve) were measured at baseline and during steady-state systemic, intravenous NTP (0...
February 28, 2018: Journal of Neurophysiology
André L Teixeira, Milena Samora, Jeann L Sabino-Carvalho
The cardiovascular response to exercise is governed by both central and peripheral mechanisms that promote alterations in parasympathetic and sympathetic neural activities to the heart and blood vessels to meet the metabolic demands of working skeletal muscle in an intensity-dependent manner. This article is protected by copyright. All rights reserved.
February 28, 2018: Journal of Physiology
Natalia Pessoa Rocha, Ana Cristina Simoes E Silva, Thiago Ruiz Rodrigues Prestes, Victor Feracin, Caroline Amaral Machado, Rodrigo Novaes Ferreira, Antonio Lucio Teixeira, Aline Silva de Miranda
BACKGROUND: The Renin-Angiotensin System (RAS) is a key regulator of cardiovascular and renal homeostasis, but also plays important roles in mediating physiological functions in the central nervous system (CNS). The effects of the RAS were classically described as mediated by angiotensin (Ang) II via angiotensin type 1 (AT1) receptors. However, another arm of the RAS formed by the angiotensin converting enzyme 2 (ACE2), Ang-(1-7) and the Mas receptor has been a matter of investigation due to its important physiological roles, usually counterbalancing the classical effects exerted by Ang II...
February 25, 2018: Current Medicinal Chemistry
Daniele J Feriani, Hélio J Coelho-Júnior, Juliana C M F de Oliveira, Maria A Delbin, Cristiano T Mostarda, Paulo M M Dourado, Érico C Caperuto, Maria C C Irigoyen, Bruno Rodrigues
Myocardial infarction (MI) remains the leading cause of morbidity and mortality worldwide. Exercise training and pharmacological treatments are important strategies to minimize the deleterious effects of MI. However, little is known about the effects of resistance training combined with pyridostigmine bromide (PYR) treatment on cardiac and autonomic function, as well as on the inflammatory profile after MI. Thus, in the present study, male Wistar rats were randomly assigned into: control (Cont); sedentary infarcted (Inf); PYR - treated sedentary infarcted rats (Inf+P); infarcted rats undergoing resistance exercise training (Inf+RT); and infarcted rats undergoing PYR treatment plus resistance training (Inf+RT+P)...
2018: Frontiers in Physiology
Ricardo S Oliveira, Alan R Barker, Florian Debras, Alexandra O'Doherty, Craig A Williams
Improvements in the autonomic and vascular systems are implicated in cardiovascular disease risk reduction. Baroreflex sensitivity (BRS) is composed of vascular and autonomic components. This study aimed to investigate between- and within-day reliability of BRS and its autonomic and vascular determinants in adolescents. Thirteen male adolescents (14·1 ± 0·5 y) participated in this study. For between-day reliability, participants completed four experimental visits separated by a minimum of 48-h. For within-day reliability, participants repeated BRS assessments three times in the morning with one hour between the measures...
February 23, 2018: Clinical Physiology and Functional Imaging
Eric A Schmidt, Fabien Despas, Anne Pavy-Le Traon, Zofia Czosnyka, John D Pickard, Kamal Rahmouni, Atul Pathak, Jean M Senard
Intracranial pressure (ICP) is the pressure within the cranium . ICP rise compresses brain vessels and reduces cerebral blood delivery. Massive ICP rise leads to cerebral ischemia, but it is also known to produce hypertension, bradycardia and respiratory irregularities due to a sympatho-adrenal mechanism termed Cushing response. One still unresolved question is whether the Cushing response is a non-synaptic acute brainstem ischemic mechanism or part of a larger physiological reflex for arterial blood pressure control and homeostasis regulation...
2018: Frontiers in Physiology
Alexandre F Cunha, Igor S A Felippe, Nilson C Ferreira-Junior, Leonardo B M Resstel, Daniela A M Guimarães, Vanessa Beijamini, Julian F R Paton, Karla N Sampaio
Although it is well-established that severe poisoning by organophosphorus (OP) compounds strongly affects the cardiorespiratory system, the effects of sub-lethal exposure to these compounds on the neural control of cardiovascular function are poorly explored. The aim of this study was to evaluate the effects of acute sub-lethal exposure to chlorpyrifos (CPF), a commonly used OP insecticide, on three basic reflex mechanisms involved in blood pressure regulation, the peripheral chemoreflex, the baroreflex and the Bezold-Jarisch reflex...
February 19, 2018: Toxicology
Josária Ferraz Amaral, Diana de Medeiros Andrade Borsato, Isabelle Magalhães Guedes Freitas, Edgar Toschi-Dias, Daniel Godoy Martinez, Mateus Camaroti Laterza
BACKGROUND: Individuals with a family history of systemic arterial hypertension (FHSAH) and / or prehypertension have a higher risk of developing this pathology. OBJECTIVE: To evaluate the autonomic and vascular functions of prehypertensive patients with FHSAH. METHODS: Twenty-five young volunteers with FHSAH, 14 normotensive and 11 prehypertensive subjects were submitted to vascular function evaluation by forearm vascular conductance(VC) during resting and reactive hyperemia (Hokanson®) and cardiac and peripheral autonomic modulation, quantified, respectively, by spectral analysis of heart rate (ECG) and systolic blood pressure (SBP) (FinometerPRO®)...
February 19, 2018: Arquivos Brasileiros de Cardiologia
Michal Javorka, Fatima El-Hamad, Barbora Czippelova, Zuzana Turianikova, Jana Krohova, Zuzana Lazarova, Mathias Baumert
The objective of this study was to determine the response of heart rate and blood pressure variability (respiratory sinus arrhythmia, baroreflex sensitivity) to orthostatic and mental stress, focussing on causality and the mediating effect of respiration. Seventy-seven healthy young volunteers (46 f, 31 m) aged 18.4 {plus minus} 2.7 years underwent an experimental protocol comprising: supine rest, 45{degree sign} head-up tilt, recovery, and a mental arithmetic task. Heart rate variability and blood pressure variability were analysed in the time and frequency domain and modelled as a multivariate autoregressive process where the respiratory volume signal acted as an external driver...
February 14, 2018: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
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