Browsing by Subject "SYMPATHETIC-NERVE ACTIVITY"

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  • Benetos, Athanase; Bulpitt, Christopher J.; Petrovic, Mirko; Ungar, Andrea; Rosei, Enrico Agabiti; Cherubini, Antonio; Redon, Josep; Grodzicki, Tomasz; Dominiczak, Anna; Strandberg, Timo; Mancia, Giuseppe (2016)
  • Orjatsalo, Maija; Alakuijala, Anniina; Partinen, Markku (2020)
    Introduction:Postural tachycardia syndrome (POTS) is a suspected dysautonomia with symptoms of orthostatic intolerance and abnormally increased heart rate while standing. We aimed to study cardiac autonomic nervous system functioning in head-up tilt (HUT) in adolescents with POTS to find out if parasympathetic tone is attenuated in the upright position. Methods:We compared characteristics of a group of 25 (females 14/25; 56%) adolescents with POTS and 12 (females 4/12; 34%) without POTS aged 9-17 years. We compared heart rate variability with high- and low-frequency oscillations, and their temporal changes in HUT. Results:The high-frequency oscillations, i.e., HF, attenuated in both groups during HUT (p<0.05), but the attenuation was bigger in POTS (p= 0.04). In the beginning of HUT, low-frequency oscillations, i.e., LF, increased more in POTS (p= 0.01), but in the end of HUT, an attenuation in LF was seen in the POTS group (p<0.05), but not in the subjects without POTS. There were no associations of previous infections or vaccinations with POTS. Subjects with POTS were sleepier and their overall quality of life was very low. Conclusion:The results imply to an impaired autonomic regulation while standing in POTS, presenting as a lower HF and higher LF in the beginning of HUT and an attenuated LF in the prolonged standing position.
  • Bernardi, Luciano; Bianchi, Lucio (2016)
    Autonomic dysfunction is a frequent and relevant complication of diabetes mellitus, as it is associated with increased morbidity and mortality. In addition, it is today considered as predictive of the most severe diabetic complications, like nephropathy and retinopathy. The classical methods of screening are the cardiovascular reflex tests and were originally interpreted as evidence of nerve damage. A more modern approach, based on the integrated control of cardiovascular and respiratory function, reveals that these abnormalities are to a great extent functional, at least in the early stage of the disease, thus suggesting new potential interventions. Therefore, this review aims to go further investigating how the imbalance of the autonomic nervous system is altered and can be influenced in many chronic pathologies through a global view of cardio-respiratory and metabolic interactions and how the same mechanisms are applicable to diabetes.
  • Ghali, Michael G. Z.; Ghali, George Z. (2020)
    Mayer waves may synchronize overlapping propriobulbar interneuronal microcircuits constituting the respiratory rhythm and pattern generator, sympathetic oscillators, and cardiac vagal preganglionic neurons. Initially described by Sir Sigmund Mayer in the year 1876 in the arterial pressure waveform of anesthetized rabbits, authors have since extensively observed these oscillations in recordings of hemodynamic variables, including arterial pressure waveform, peripheral resistance, and blood flow. Authors would later reveal the presence of these oscillations in sympathetic neural efferent discharge and brainstem and spinal zones corresponding with sympathetic oscillators. Mayer wave central tendency proves highly consistent within, though the specific frequency band varies extensively across, species. Striking resemblance of the Mayer wave central tendency to the species-specific baroreflex resonant frequency has led the majority of investigators to comfortably presume, and generate computational models premised upon, a baroreflex origin of these oscillations. Empirical interrogation of this conjecture has generated variable results and derivative interpretations. Sinoaortic denervation and effector sympathectomy variably reduces or abolishes spectral power contained within the Mayer wave frequency band. Refractorines of Mayer wave generation to barodeafferentation lends credence to the hypothesis these waves are chiefly generated by brainstem propriobulbar and spinal cord propriospinal interneuronal microcircuit oscillators and likely modulated by the baroreflex. The presence of these waves in unitary discharge of medullary lateral tegmental field and rostral ventrolateral medullary neurons (contemporaneously exhibiting fast sympathetic rhythms [2-6 and 10 Hz bands]) in spectral variability in vagotomized pentobarbital-anesthetized and unanesthetized midcollicular (i.e., intercollicular) decerebrate cats supports genesis of Mayer waves by supraspinal sympathetic microcircuit oscillators. Persistence of these waves following high cervical transection in vagotomized unanesthetized midcollicular decerebrate cats would seem to suggestspinalsympathetic microcircuit oscillators generate these waves. The widespread presence of Mayer waves in brainstem sympathetic-related and non-sympathetic-related cells would seem to betray a general tendency of neurons to oscillate at this frequency. We have thus presented an extensive and, hopefully cohesive, discourse evaluating, and evolving the interpretive consideration of, evidence seeking to illumine our understanding of origins of, and insight into mechanisms contributing to, the genesis of Mayer waves. We have predicated our arguments and conjectures in the substance and matter of empirical data, though we have occasionally waxed philosophical beyond these traditional confines in suggesting interpretations exceeding these limits. We believe our synthesis and interpretation of the relevant literature will fruitfully inspire future studies from the perspective of a more intimate appreciation and conceptualization of network mechanisms generating oscillatory variability in neuronal and neural outputs. Our evaluation of Mayer waves informs a novel set of disciplines we term quantum neurophysics extendable to describing subatomic reality. Beyond informing our appreciation of mechanisms generating sympathetic oscillations, Mayer waves may constitute an intrinsic property of neurons extant throughout the cerebrum, brainstem, and spinal cord or reflect an emergent property of interactions between arteriogenic and neuronal oscillations.
  • Bernardi, Luciano; Gordin, Daniel; Bordino, Marco; Rosengard-Barlund, Milla; Sandelin, Anna; Forsblom, Carol; Groop, Per-Henrik (2017)
    Hyperoxia and slow breathing acutely improve autonomic function in type-1 diabetes. However, their effects on arterial function may reveal different mechanisms, perhaps potentially useful. To test the effects of oxygen and slow breathing we measured arterial function (augmentation index, pulse wave velocity), baroreflex sensitivity (BRS) and oxygen saturation (SAT), during spontaneous and slow breathing (6 breaths/min), in normoxia and hyperoxia (5 L/min oxygen) in 91 type-1 diabetic and 40 age-matched control participants. During normoxic spontaneous breathing diabetic subjects had lower BRS and SAT, and worse arterial function. Hyperoxia and slow breathing increased BRS and SAT. Hyperoxia increased blood pressure and worsened arterial function. Slow breathing improved arterial function and diastolic blood pressure. Combined administration prevented the hyperoxia-induced arterial pressure and function worsening. Control subjects showed a similar pattern, but with lesser or no statistical significance. Oxygen-driven autonomic improvement could depend on transient arterial stiffening and hypertension (well-known irritative effect of free-radicals on endothelium), inducing reflex increase in BRS. Slow breathing-induced improvement in BRS may result from improved SAT, reduced sympathetic activity and improved vascular function, and/or parasympathetic-driven antioxidant effect. Lower oxidative stress could explain blunted effects in controls. Slow breathing could be a simple beneficial intervention in diabetes.
  • Pyykkö, Ilmari; Manchaiah, Vinaya; Zou, Jing; Levo, Hiha; Kentala, Erna (2018)
    Objective: Experiments in humans and animals indicate that vestibular influx through vestibular sympathetic reflex is an important and vital part of the regulatory system of circulation. The otolith organ adjusts the circulatory responses through the vestibular sympathetic reflex during an upright stance and may trigger a vasovagal attack of syncope. The aim of the present study was to evaluate the prevalence and association of syncope attacks among patients with Meniere's disease (MD). Vestibular syncope was defined as a sudden and transient loss of consciousness, which subsides spontaneously in people with vestibular disorders and without localizing neurological deficit. Methods: During clinical interactions, we encountered 5 patients with syncope during a Tumarkin attack of MD. Thereafter we evaluated data from 952 patients collected with a questionnaire from the Finnish Meniere Association (FMA). The data contained case histories with special attention to Tumarkin attacks, participation restriction, migraines, and syncope attacks. The mean age of the subjects participating in the study was 60.6 years (range 25-75 years). The duration of the disease was on average 9.8 years (range 0.5-35 years). Results: In the current study sample, attacks of syncope were reported by 38 patients (4%) in association with the vertigo attack. Syncope was associated with Tumarkin attacks (X-2 = 16.7, p <0.001), migraine (X-2 = 7.4, p <0.011), history of ischemic heart disease (X-2 = 6.0, p <0.025), and history of cerebrovascular disease (X-2 = 11.7, p <0.004). Duration of MD was correlated with syncope. Syncope was provoked by physical strain and environmental pressure, and was associated with impairment of the visual field (i.e., visual blurring). In logistic regression analysis, syncope was significantly associated with Tumarkin attacks (odds ratio 3.2), migraines (odds ratio 2.3) and nausea (odds ratio 1.3). The attack of syncope was experienced as frightening, and general health related quality of life (HRQoL) was significantly worsened. Also, the patients suffered more from fatigue. Conclusion: The current study indicates that patients with MD who suffer from Tumarkin attacks can suffer from syncope. It confirms the role of the otolith organ in controlling the circulatory homeostasis of the body. The actions are mediated through the vestibular sympathetic reflex. (C) 2017 Elsevier B.V. All rights reserved.