A response by the BARORECEPTORS to increased BLOOD PRESSURE. Increased pressure stretches BLOOD VESSELS which activates the baroreceptors in the vessel walls. The net response of the CENTRAL NERVOUS SYSTEM is a reduction of central sympathetic outflow. This reduces blood pressure both by decreasing peripheral VASCULAR RESISTANCE and by lowering CARDIAC OUTPUT. Because the baroreceptors are tonically active, the baroreflex can compensate rapidly for both increases and decreases in blood pressure.
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.
The thoracolumbar division of the autonomic nervous system. Sympathetic preganglionic fibers originate in neurons of the intermediolateral column of the spinal cord and project to the paravertebral and prevertebral ganglia, which in turn project to target organs. The sympathetic nervous system mediates the body's response to stressful situations, i.e., the fight or flight reactions. It often acts reciprocally to the parasympathetic system.
An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.
The dilated portion of the common carotid artery at its bifurcation into external and internal carotids. It contains baroreceptors which, when stimulated, cause slowing of the heart, vasodilatation, and a fall in blood pressure.
The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).
The ENTERIC NERVOUS SYSTEM; PARASYMPATHETIC NERVOUS SYSTEM; and SYMPATHETIC NERVOUS SYSTEM taken together. Generally speaking, the autonomic nervous system regulates the internal environment during both peaceful activity and physical or emotional stress. Autonomic activity is controlled and integrated by the CENTRAL NERVOUS SYSTEM, especially the HYPOTHALAMUS and the SOLITARY NUCLEUS, which receive information relayed from VISCERAL AFFERENTS.
An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.
GRAY MATTER located in the dorsomedial part of the MEDULLA OBLONGATA associated with the solitary tract. The solitary nucleus receives inputs from most organ systems including the terminations of the facial, glossopharyngeal, and vagus nerves. It is a major coordinator of AUTONOMIC NERVOUS SYSTEM regulation of cardiovascular, respiratory, gustatory, gastrointestinal, and chemoreceptive aspects of HOMEOSTASIS. The solitary nucleus is also notable for the large number of NEUROTRANSMITTERS which are found therein.
Cardiac arrhythmias that are characterized by excessively slow HEART RATE, usually below 50 beats per minute in human adults. They can be classified broadly into SINOATRIAL NODE dysfunction and ATRIOVENTRICULAR BLOCK.
Forced expiratory effort against a closed GLOTTIS.
The resection or removal of the nerve to an organ or part. (Dorland, 28th ed)
The HEART and the BLOOD VESSELS by which BLOOD is pumped and circulated through the body.
Sense of awareness of self and of the environment.
The posture of an individual lying face up.
A nicotinic antagonist that has been used as a ganglionic blocker in hypertension, as an adjunct to anesthesia, and to induce hypotension during surgery.
The vessels carrying blood away from the heart.
Drugs used to cause constriction of the blood vessels.
An abnormal response to a stimulus applied to the sensory components of the nervous system. This may take the form of increased, decreased, or absent reflexes.
Processes and properties of the CARDIOVASCULAR SYSTEM as a whole or of any of its parts.
The hollow, muscular organ that maintains the circulation of the blood.
External decompression applied to the lower body. It is used to study orthostatic intolerance and the effects of gravitation and acceleration, to produce simulated hemorrhage in physiologic research, to assess cardiovascular function, and to reduce abdominal stress during childbirth.
A standard and widely accepted diagnostic test used to identify patients who have a vasodepressive and/or cardioinhibitory response as a cause of syncope. (From Braunwald, Heart Disease, 7th ed)
The craniosacral division of the autonomic nervous system. The cell bodies of the parasympathetic preganglionic fibers are in brain stem nuclei and in the sacral spinal cord. They synapse in cranial autonomic ganglia or in terminal ganglia near target organs. The parasympathetic nervous system generally acts to conserve resources and restore homeostasis, often with effects reciprocal to the sympathetic nervous system.
A significant drop in BLOOD PRESSURE after assuming a standing position. Orthostatic hypotension is a finding, and defined as a 20-mm Hg decrease in systolic pressure or a 10-mm Hg decrease in diastolic pressure 3 minutes after the person has risen from supine to standing. Symptoms generally include DIZZINESS, blurred vision, and SYNCOPE.
The neural systems which act on VASCULAR SMOOTH MUSCLE to control blood vessel diameter. The major neural control is through the sympathetic nervous system.
Agents having as their major action the interruption of neural transmission at nicotinic receptors on postganglionic autonomic neurons. Because their actions are so broad, including blocking of sympathetic and parasympathetic systems, their therapeutic use has been largely supplanted by more specific drugs. They may still be used in the control of blood pressure in patients with acute dissecting aortic aneurysm and for the induction of hypotension in surgery.
Either of the two principal arteries on both sides of the neck that supply blood to the head and neck; each divides into two branches, the internal carotid artery and the external carotid artery.
Posture while lying with the head lower than the rest of the body. Extended time in this position is associated with temporary physiologic disturbances.
Abnormally rapid heartbeat, usually with a HEART RATE above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia.
The lateral of the two terminal branches of the sciatic nerve. The peroneal (or fibular) nerve provides motor and sensory innervation to parts of the leg and foot.
The position or attitude of the body.
An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness.
Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.
Diseases of the parasympathetic or sympathetic divisions of the AUTONOMIC NERVOUS SYSTEM; which has components located in the CENTRAL NERVOUS SYSTEM and PERIPHERAL NERVOUS SYSTEM. Autonomic dysfunction may be associated with HYPOTHALAMIC DISEASES; BRAIN STEM disorders; SPINAL CORD DISEASES; and PERIPHERAL NERVOUS SYSTEM DISEASES. Manifestations include impairments of vegetative functions including the maintenance of BLOOD PRESSURE; HEART RATE; pupil function; SWEATING; REPRODUCTIVE AND URINARY PHYSIOLOGY; and DIGESTION.
The blood pressure in the central large VEINS of the body. It is distinguished from peripheral venous pressure which occurs in an extremity.
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
The removal or interruption of some part of the autonomic nervous system for therapeutic or research purposes.
Diseases of the tenth cranial nerve, including brain stem lesions involving its nuclei (solitary, ambiguus, and dorsal motor), nerve fascicles, and intracranial and extracranial course. Clinical manifestations may include dysphagia, vocal cord weakness, and alterations of parasympathetic tone in the thorax and abdomen.
Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.
The lower portion of the BRAIN STEM. It is inferior to the PONS and anterior to the CEREBELLUM. Medulla oblongata serves as a relay station between the brain and the spinal cord, and contains centers for regulating respiratory, vasomotor, cardiac, and reflex activities.
Drugs that mimic the effects of stimulating postganglionic adrenergic sympathetic nerves. Included here are drugs that directly stimulate adrenergic receptors and drugs that act indirectly by provoking the release of adrenergic transmitters.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.
Plethysmographic determination in which the intensity of light reflected from the skin surface and the red cells below is measured to determine the blood volume of the respective area. There are two types, transmission and reflectance.
Drugs used to cause dilation of the blood vessels.
A change in cardiovascular function resulting in a reduction in BLOOD VOLUME, and reflex DIURESIS. It occurs frequently after actual or simulated WEIGHTLESSNESS.
Double-layered inflatable suits which, when inflated, exert pressure on the lower part of the wearer's body. The suits are used to improve or stabilize the circulatory state, i.e., to prevent hypotension, control hemorrhage, and regulate blood pressure. The suits are also used by pilots under positive acceleration.
The rhythmical expansion and contraction of an ARTERY produced by waves of pressure caused by the ejection of BLOOD from the left ventricle of the HEART as it contracts.
The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.
Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.
An irregularly shaped cavity in the RHOMBENCEPHALON, located between the MEDULLA OBLONGATA; the PONS; and the isthmus in front, and the CEREBELLUM behind. It is continuous with the central canal of the cord below and with the CEREBRAL AQUEDUCT above, and through its lateral and median apertures it communicates with the SUBARACHNOID SPACE.
Nerve fibers which project from sympathetic ganglia to synapses on target organs. Sympathetic postganglionic fibers use norepinephrine as transmitter, except for those innervating eccrine sweat glands (and possibly some blood vessels) which use acetylcholine. They may also release peptide cotransmitters.
Cells specialized to detect chemical substances and relay that information centrally in the nervous system. Chemoreceptor cells may monitor external stimuli, as in TASTE and OLFACTION, or internal stimuli, such as the concentrations of OXYGEN and CARBON DIOXIDE in the blood.
An octapeptide that is a potent but labile vasoconstrictor. It is produced from angiotensin I after the removal of two amino acids at the C-terminal by ANGIOTENSIN CONVERTING ENZYME. The amino acid in position 5 varies in different species. To block VASOCONSTRICTION and HYPERTENSION effect of angiotensin II, patients are often treated with ACE INHIBITORS or with ANGIOTENSIN II TYPE 1 RECEPTOR BLOCKERS.
The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.
Physical activity which is usually regular and done with the intention of improving or maintaining PHYSICAL FITNESS or HEALTH. Contrast with PHYSICAL EXERTION which is concerned largely with the physiologic and metabolic response to energy expenditure.
The delivery of a drug into a fluid-filled cavity of the brain.
The blood pressure in the ARTERIES. It is commonly measured with a SPHYGMOMANOMETER on the upper arm which represents the arterial pressure in the BRACHIAL ARTERY.
A degenerative disease of the AUTONOMIC NERVOUS SYSTEM that is characterized by idiopathic ORTHOSTATIC HYPOTENSION and a greatly reduced level of CATECHOLAMINES. No other neurological deficits are present.
A strain of Rattus norvegicus with elevated blood pressure used as a model for studying hypertension and stroke.
Analogs and derivatives of atropine.
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.
The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (= OXYGEN CONSUMPTION) or cell respiration (= CELL RESPIRATION).
Injections into the cerebral ventricles.
Loss of consciousness due to a reduction in blood pressure that is associated with an increase in vagal tone and peripheral vasodilation.
A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.
The dilatation of the aortic wall behind each of the cusps of the aortic valve.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
Abnormally low BLOOD PRESSURE that can result in inadequate blood flow to the brain and other vital organs. Common symptom is DIZZINESS but greater negative impacts on the body occur when there is prolonged depravation of oxygen and nutrients.
The part of a human or animal body connecting the HEAD to the rest of the body.
The physical or mechanical action of the LUNGS; DIAPHRAGM; RIBS; and CHEST WALL during respiration. It includes airflow, lung volume, neural and reflex controls, mechanoreceptors, breathing patterns, etc.
A volatile vasodilator which relieves ANGINA PECTORIS by stimulating GUANYLATE CYCLASE and lowering cytosolic calcium. It is also sometimes used for TOCOLYSIS and explosives.
The interruption or removal of any part of the vagus (10th cranial) nerve. Vagotomy may be performed for research or for therapeutic purposes.
Transmission of the readings of instruments to a remote location by means of wires, radio waves, or other means. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Nerve fibers liberating catecholamines at a synapse after an impulse.
The removal of secretions, gas or fluid from hollow or tubular organs or cavities by means of a tube and a device that acts on negative pressure.
An antagonist of ANGIOTENSIN TYPE 1 RECEPTOR with antihypertensive activity due to the reduced pressor effect of ANGIOTENSIN II.
Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.
The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).

Effects of amlodipine on sympathetic nerve traffic and baroreflex control of circulation in heart failure. (1/1596)

Short-acting calcium antagonists exert a sympathoexcitation that in heart failure further enhances an already elevated sympathetic activity. Whether this is also the case for long-acting formulations is not yet established, despite the prognostic importance of sympathetic activation in heart failure. It is also undetermined whether in this condition long-acting calcium antagonists favorably affect a mechanism potentially responsible for the sympathetic activation, ie, the baroreflex impairment. In 28 heart failure patients (NYHA functional class II) under conventional treatment we measured plasma norepinephrine and efferent postganglionic muscle sympathetic nerve activity (microneurography) at rest and during arterial baroreceptor stimulation and deactivation induced by stepwise intravenous infusions of phenylephrine and nitroprusside, respectively. Measurements were performed at baseline and after 8 weeks of daily oral amlodipine administration (10 mg/d, 14 patients) or before and after an 8-week period without calcium antagonist administration (14 patients). Amlodipine caused a small and insignificant blood pressure reduction. Heart rate, left ventricular ejection fraction, and plasma renin and aldosterone concentrations were not affected. This was the case also for plasma norepinephrine (from 2.43+/-0.41 to 2.50+/-0.34 nmol/L, mean+/-SEM), muscle sympathetic nerve activity (from 54.4+/-5.9 to 51.0+/-4.3 bursts/min), and arterial baroreflex responses. No change in the above-mentioned variables was seen in the control group. Thus, in mild heart failure amlodipine treatment does not adversely affect sympathetic activity and baroreflex control of the heart and sympathetic tone. This implies that in this condition long-acting calcium antagonists can be administered without untoward neurohumoral effects anytime conventional treatment needs to be complemented by drugs causing additional vasodilatation.  (+info)

A method for determining baroreflex-mediated sympathetic and parasympathetic control of the heart in pregnant and non-pregnant sheep. (2/1596)

1. The cardiac baroreflex was measured in four non-pregnant and six pregnant ewes before and during beta-adrenoreceptor blockade with propranolol and before and during vagal blockade with atropine. Arterial pressure was raised by phenylephrine and lowered by sodium nitroprusside. The relationships between mean arterial pressure (MAP) and heart rate (HR), between MAP and heart rate variability (HRV) measured as the coefficient of variation (c.v.) of the mean pulse interval (PI), and between MAP and HRV measured by power spectral analysis were determined. 2. The MAP-HR relationship showed that in pregnant ewes the gain of the cardiac baroreflex was reduced when compared with non-pregnant ewes. Threshold and saturation pressures were higher, maximum achievable HR was lower and there was a decrease in the operating range. 3. V-shaped relationships were obtained between MAP and HRV (measured as the c.v. of PI) and between MAP and power spectral density in the frequency range 0.04-0. 08 Hz. Using selective autonomic blockade the negative, or downward, slope of the V shape was shown to be a measure of baroreceptor-induced, sympathetically mediated effects on HRV. The upward, or positive, slope of the V shape was a measure of baroreceptor-induced, vagally mediated effects. Similar results were also obtained from the cardiac power spectrum, but it was less sensitive. The MAP at which the two slopes intersected was the same as the resting MAP. 4. In pregnant ewes, the slope of the downward limb of the V-shaped relationship between HRV (when measured as the c.v. of PI) and MAP was less than in non-pregnant ewes. 5. The relationship between MAP and the coefficient of variation of the mean pulse interval can therefore be used to measure the degree to which baroreceptor-induced sympathetic and parasympathetic activity affects the heart. 6. The resting MAP is the pressure at which the net effect of these sympathetic and parasympathetic influences on the heart is at a minimum. Studies of both the MAP-HR and MAP-HRV relationships in pregnant and non-pregnant sheep show that in pregnant sheep, there is attenuation of baroreceptor-mediated sympathetic effects on the heart.  (+info)

Vasopressin V2 receptor enhances gain of baroreflex in conscious spontaneously hypertensive rats. (3/1596)

The aim of the present study was to determine the receptor subtype involved in arginine vasopressin (AVP)-induced modulation of baroreflex function in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats using novel nonpeptide AVP V1- and V2-receptor antagonists. Baroreceptor heart rate (HR) reflex was investigated in both SHR and WKY rats which were intravenously administered the selective V1- and V2-receptor antagonists OPC-21268 and OPC-31260, respectively. Baroreflex function was assessed by obtaining alternate pressor and depressor responses to phenylephrine and sodium nitroprusside, respectively, to construct baroreflex curves. In both SHR and WKY rats baroreflex activity was tested before and after intravenous administration of vehicle (20% DMSO), OPC-21268 (10 mg/kg), and OPC-31260 (1 and 10 mg/kg). Vehicle did not significantly alter basal mean arterial pressure (MAP) and HR values or baroreflex function in SHR or WKY rats. The V1-receptor antagonist had no significant effect on resting MAP or HR values or on baroreflex parameters in both groups of rats, although this dose was shown to significantly inhibit the pressor response to AVP (5 ng iv; ANOVA, P < 0.05). In SHR but not WKY rats the V2-receptor antagonist significantly attenuated the gain (or slope) of the baroreflex curve (to 73 +/- 3 and 79 +/- 7% of control for 1 and 10 mg/kg, respectively), although AVP-induced pressor responses were also attenuated with the higher dose of the V2-receptor antagonist. These findings suggest that AVP tonically enhances baroreflex function through a V2 receptor in the SHR.  (+info)

Cardiac baroreflex during the postoperative period in patients with hypertension: effect of clonidine. (4/1596)

BACKGROUND: Patients with essential hypertension show altered baroreflex control of heart rate, and during the perioperative period they demonstrate increased circulatory instability. Clonidine has been shown to reduce perioperative circulatory instability. This study documents changes in measures of heart rate control after surgery in patients with essential hypertension and determines the effects of clonidine on postoperative heart rate control in these patients. METHODS: Using a randomized double-blind placebo-controlled design, 20 patients with essential hypertension (systolic pressure >160 mm Hg or diastolic pressure >95 mm Hg for > or =1 yr) were assigned to receive clonidine (or placebo), 6 microg/kg orally 120 min before anesthesia and 3 microg/kg intravenously over 60 min before the end of surgery. The spontaneous baroreflex ("sequence") technique and analysis of heart rate variability were used to quantify control of heart rate at baseline, before induction of anesthesia, and 1 and 3 h postoperatively. RESULTS: Baroreflex slope and heart rate variability were reduced postoperatively in patients given placebo but not those given clonidine. Clonidine resulted in greater postoperative baroreflex slope and power at all frequency ranges compared with placebo (4.9+/-2.9 vs. 2.2+/-2.1 ms/mm Hg for baroreflex slope, 354+/-685 vs. 30+/-37 ms2/Hz for high frequency variability). Clonidine also resulted in lower concentrations of catecholamine, decreased mean heart rate and blood pressure, and decreased perioperative tachycardia and hypertension. CONCLUSIONS: Patients with hypertension exhibit reduced heart rate control during the recovery period after elective surgery. Clonidine prevents this reduction in heart rate control. This may represent a basis for the improved circulatory stability seen with perioperative administration of clonidine.  (+info)

Hypoxia inhibits baroreflex vagal bradycardia via a central action in anaesthetized rats. (5/1596)

It is known that arterial baroreflexes are suppressed in stressful conditions. The present study was designed to determine whether and how hypoxia affects arterial baroreflexes, especially the heart rate component, baroreflex vagal bradycardia. In chloralose-urethane-anaesthetized rats, baroreflex vagal bradycardia was evoked by electrical stimulation of the aortic depressor nerve, and the effect of 15 s inhalation of hypoxic gas (4% O2) was studied. Inhalation of hypoxic gas was found to inhibit baroreflex vagal bradycardia. The inhibition persisted after bilateral transection of the carotid sinus nerve. Cervical vagus nerves were cut bilaterally and their peripheral cut ends were stimulated to provoke vagal bradycardia of peripheral origin so as to determine whether hypoxia could inhibit vagal bradycardia by acting on a peripheral site. In contrast to baroreflex vagal bradycardia, the vagus-induced bradycardia was not affected by hypoxic gas inhalation. It is concluded that baroreflex vagal bradycardia is inhibited by hypoxia and the inhibition is largely mediated by its direct central action.  (+info)

Prognostic value of nocturnal Cheyne-Stokes respiration in chronic heart failure. (6/1596)

BACKGROUND: Nocturnal Cheyne-Stokes respiration (CSR) occurs frequently in patients with chronic heart failure (CHF), and it may be associated with sympathetic activation. The aim of the present study was to evaluate whether CSR could affect prognosis in patients with CHF. METHODS AND RESULTS: Sixty-two CHF patients with left ventricular ejection fraction /=30/h and left atria >/=25 cm2. CONCLUSIONS: The AHI is a powerful independent predictor of poor prognosis in clinically stable patients with CHF. The presence of an AHI >/=30/h adds prognostic information compared with other clinical, echocardiographic, and autonomic data and identifies patients at very high risk for subsequent cardiac death.  (+info)

The rostral ventrolateral medulla mediates the sympathoactivation produced by chemical stimulation of the rat nasal mucosa. (7/1596)

1. We sought to outline the brainstem circuit responsible for the increase in sympathetic tone caused by chemical stimulation of the nasal passages with ammonia vapour. Experiments were performed in alpha-chloralose-anaesthetized, paralysed and artificially ventilated rats. 2. Stimulation of the nasal mucosa increased splanchnic sympathetic nerve discharge (SND), elevated arterial blood pressure (ABP), raised heart rate slightly and inhibited phrenic nerve discharge. 3. Bilateral injections of the broad-spectrum excitatory amino acid receptor antagonist kynurenate (Kyn) into the rostral part of the ventrolateral medulla (RVLM; rostral C1 area) greatly reduced the effects of nasal mucosa stimulation on SND (-80 %). These injections had no effect on resting ABP, resting SND or the sympathetic baroreflex. 4. Bilateral injections of Kyn into the ventrolateral medulla at the level of the obex (caudal C1 area) or into the nucleus tractus solitarii (NTS) greatly attenuated the baroreflex and significantly increased the baseline levels of both SND and ABP. However they did not reduce the effect of nasal mucosa stimulation on SND. 5. Single-unit recordings were made from 39 putative sympathoexcitatory neurons within the rostral C1 area. Most neurons (24 of 39) were activated by nasal mucosa stimulation (+65.8 % rise in discharge rate). Responding neurons had a wide range of conduction velocities and included slow-conducting neurons identified previously as C1 cells. The remaining putative sympathoexcitatory neurons were either unaffected (n = 8 neurons) or inhibited (n = 7) during nasal stimulation. We also recorded from ten respiratory-related neurons, all of which were silenced by nasal stimulation. 6. In conclusion, the sympathoexcitatory response to nasal stimulation is largely due to activation of bulbospinal presympathetic neurons within the RVLM. We suggest that these neurons receive convergent and directionally opposite polysynaptic inputs from arterial baroreceptors and trigeminal afferents. These inputs are integrated within the rostral C1 area as opposed to the NTS or the caudal C1 area.  (+info)

Investigating feed-forward neural regulation of circulation from analysis of spontaneous arterial pressure and heart rate fluctuations. (8/1596)

BACKGROUND: Analysis of spontaneous fluctuations in systolic arterial pressure (SAP) and pulse interval (PI) reveals the occurrence of sequences of consecutive beats characterized by SAP and PI changing in the same (+PI/+SAP and -PI/-SAP) or opposite (-PI/+SAP and +PI/-SAP) direction. Although the former reflects baroreflex regulatory mechanisms, the physiological meaning of -PI/+SAP and +PI/-SAP is unclear. We tested the hypothesis that -PI/+SAP and +PI/-SAP "nonbaroreflex" sequences represent a phenomenon modulated by the autonomic nervous system reflecting a feed-forward mechanism of cardiovascular regulation. METHODS AND RESULTS: We studied anesthetized rabbits before and after (1) complete autonomic blockade (guanethidine+propranolol+atropine, n=13; CAB), (2) sympathetic blockade (guanethidine+propranolol, n=15; SB), (3) parasympathetic blockade (atropine, n=16), (4) sinoaortic denervation (n=10; SAD), and (5) controlled respiration (n=10; CR). Nonbaroreflex sequences were defined as >/=3 beats in which SAP and PI of the following beat changed in the opposite direction. CAB reduced the number of nonbaroreflex sequences (19. 1+/-12.3 versus 88.7+/-36.6, P<0.05), as did SB (25.3+/-11.7 versus 84.6+/-23.9, P<0.001) and atropine (11.2+/-6.8 versus 94.1+/-32.4, P<0.05). SB concomitantly increased baroreflex sensitivity (1.18+/-0. 11 versus 0.47+/-0.09 ms/mm Hg, P<0.01). SAD and CR did not significantly affect their occurrence. CONCLUSIONS: These results suggest that nonbaroreflex sequences represent the expression of an integrated, neurally mediated, feed-forward type of short-term cardiovascular regulation able to interact dynamically with the feedback mechanisms of baroreflex origin in the control of heart period.  (+info)

Introduction: Muscle sympathetic nerve activity (MSNA) and forearm blood flow (FBF) are markers of mortality in Systolic Heart Failure (S-HF). Endomyocardial Fibrosis (EMF) is a Heart Failure (HF) with Preserved Ejection Fraction (PEF-HF). Although mortality in PEF-HF can be similar to S-HF, it is still unknown if neurovascular control is impaired in PEF-HF.. Hypothesis: Our hypothesis is that even though PEF-HF show normal ejection fraction, they have the same autonomic dysfunction as S-HF. The aim was to evaluate MSNA, FBF and spontaneous baroreflex sensitivity (SBS) in PEF-HF compared to S-HF and healthy subjects (HS).. Methods: Nineteen females HF, NYHA class II and III, were divided in two groups: PEF-HF (n=10) and S-HF (n=9), and were compared to HS (n=7). Left Ventricular Ejection Fraction (LVEF), by echocardiography (Simpson); MSNA, by microneurography; FBF, by venous occlusion plethysmography; mean blood pressure (MBP) and heart rate (HR) by Finometer; SBS, by sequence method, were ...
An aspect of the present subject matter relates to a system for providing baroreflex stimulation. An embodiment of the system comprises an adverse event detector to sense an adverse event and provide a signal indicative of the adverse event, and a baroreflex stimulator. The stimulator includes a pulse generator to provide a baroreflex stimulation signal adapted to provide a baroreflex therapy, and a modulator to receive the signal indicative of the adverse event and modulate the baroreflex stimulation signal based on the signal indicative of the adverse event to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy. Other aspects are provided herein.
Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the patient, and a processor coupled with the baroreflex activation device(s) and the sensor(s) for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, the system is fully implantable within a patient, such as in an intravascular, extravascular or intramural location.
Baroreflex sensitivity can be enhanced significantly by slow breathing, both in health and in the presence of CHF. This seems to occur through a relative increase in vagal activity and a reduction in sympathetic activity, as could be argued by the small reduction in heart rate observed during slow breathing and by the reduction in both systolic and diastolic blood pressures. The increase in tidal volume, which compensates for the reduced breathing rate in order to maintain minute ventilation,6,8 could be responsible for these autonomic changes through a reduction in sympathetic activity8 or via the Hering-Breuer reflex. In fact, sympathetic activity was found to increase with faster breathing rates and to decrease with higher tidal volumes in CHF.8,10 The increase in baroreflex sensitivity depended on the slow breathing rate and not on the regularization obtained by controlling the breathing, inasmuch as this effect was not evident when breathing was controlled at a frequency (15 breaths/min) ...
Arterial baroreflex and cardiac autonomic control play important roles in hemodynamic instability after carotid artery stenting (CAS). Spontaneous baroreflex sensitivity (BRS), heart rate variability (HRV) and blood pressure variability (BPV) are established tools for the assessment of arterial baroreflex and cardiac autonomic activity. Aim of the study was to evaluate cardiac autonomic activity (by means of HRV, BPV and BRS) after CAS and to explore the impact of internal carotid artery stenosis on BRS changes after CAS. 37 patients (68±10.45 years) with internal carotid stenosis underwent CAS. HRV, BPV and BRS were measured in all subjects before and at 1 and 72h after CAS. ANOVA was performed to compare BRS, HRV and BPV parameters before and after CAS. Spearman analysis was performed to determine a possible correlation between carotid stenosis degree (or carotid plaque diameter) and BRS changes (ΔBRS). LF/HF (index of sympatho-vagal balance) decreased during postoperative period, in ...
BACKGROUND--Disturbances of autonomic function are recognised in both the acute and convalescent phases of myocardial infarction. Recent studies have suggested that disordered autonomic function, particularly the loss of protective vagal reflexes, is associated with an increased incidence of arrhythmic deaths. The purpose of this study was to compare the value of differing prognostic indicators with measures of autonomic function and to assess the safety of arterial baroreflex testing early after infarction. METHODS--As part of a prospective trial of risk stratification in post-infarction patients arterial baroreflex sensitivity, heart rate variability, long term electrocardiographic recordings, exercise stress testing, and ejection fraction were recorded between days 7 and 10 in 122 patients with acute myocardial infarction. RESULTS--During a one year follow up period there were 10 arrhythmic events. Baroreflex sensitivity was appreciably reduced in these patients suffering arrhythmic events ...
Salt-sensitive hypertension is known to be associated with dysfunction of the baroreflex control system in the Dahl salt-sensitive (SS) rat. However, neither the physiological mechanisms nor the genomic regions underlying the baroreflex dysfunction seen in this rat model are definitively known. Here, we have adopted a mathematical modeling approach to investigate the physiological and genetic origins of baroreflex dysfunction in the Dahl SS rat. We have developed a computational model of the overall baroreflex heart rate control system based on known physiological mechanisms to analyze telemetry-based blood pressure and heart rate data from two genetic strains of rat, the SS and consomic SS.13BN, on low- and high-salt diets. With this approach, physiological parameters are estimated, unmeasured physiological variables related to the baroreflex control system are predicted, and differences in these quantities between the two strains of rat on low- and high-salt diets are detected. Specific ...
Naloxone, an opioid antagonist, augments baroreflex mechanisms in animals; this occurrence suggests that endogenous opioids blunt baroreflex responses. Limited human studies suggest an inhibitory action of endogenous opioids on baroreflex-mediated vagal responses during arterial baroreceptor deactivation. To evaluate the potential effect of endogenous opioids on cardiopulmonary baroreflex mechanisms in humans, we measured arterial and central venous pressures, heart rate, and efferent muscle sympathetic nerve activity (MSNA, by peroneal microneurography) during unloading of cardiopulmonary baroreceptors with incremental lower body negative pressure (LBNP, from 0 to -15 mm Hg) and during the cold pressor test in 21 normal subjects (aged 24 +/- 1 [mean +/- SEM] years). In 14 subjects, we performed LBNP before and after naloxone (0.15 mg/kg i.v.) and placebo (n = 11) on separate days. In six of these 14 subjects and an additional seven subjects (n = 13), studies were also performed before and after ...
Carotid baroreflex activation has been demonstrated to provide enduring reductions in arterial blood pressure. The aim of this study was to investigate the effect of long-term therapy on renal function. A total of 322 patients were enrolled in the Rheos Pivotal Trial. Group 1 consisted of 236 patients who started baroreflex activation therapy 1 month after device implantation, whereas in the 86 patients from group 2 the device was activated 6 months later. Serum creatinine and urine albumin/creatinine ratio were collected at screening (before device activation), and at months 6 and 12. Multilevel statistical analyses were adjusted for various covariables. Serum creatinine increased from 78 to 84 μmol/L, and glomerular filtration rate decreased from 92 to 87 mL/min per 1.73 m2 in group 1 at month 6 (P,0.05). These values did not change any further after 12 months of therapy. Patients with highest glomerular filtration rate showed the greatest decrease in glomerular filtration. Group 2 showed the ...
The baroreflex or baroreceptor reflex is one of the bodys homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure reflexively causes the heart rate to decrease and also causes blood pressure to decrease. Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels. The baroreflex can begin to act in less than the duration of a cardiac cycle (fractions of a second) and thus baroreflex adjustments are key factors in dealing with postural hypotension, the tendency for blood pressure to decrease on standing due to gravity. The system relies on specialized neurons, known as baroreceptors, in the aortic arch, carotid sinuses, and elsewhere to monitor changes in blood pressure and relay them to the Medulla. Baroreceptors are stretch receptors and respond to the pressure induced stretching of the blood vessel in ...
TY - JOUR. T1 - Cellular and Molecular Mechanisms Underlying Arterial Baroreceptor Remodeling in Cardiovascular Diseases and Diabetes. AU - Tu, Huiyin. AU - Zhang, Dongze. AU - Li, Yu Long. PY - 2019/2/1. Y1 - 2019/2/1. N2 - Clinical trials and animal experimental studies have demonstrated an association of arterial baroreflex impairment with the prognosis and mortality of cardiovascular diseases and diabetes. As a primary part of the arterial baroreflex arc, the pressure sensitivity of arterial baroreceptors is blunted and involved in arterial baroreflex dysfunction in cardiovascular diseases and diabetes. Changes in the arterial vascular walls, mechanosensitive ion channels, and voltage-gated ion channels contribute to the attenuation of arterial baroreceptor sensitivity. Some endogenous substances (such as angiotensin II and superoxide anion) can modulate these morphological and functional alterations through intracellular signaling pathways in impaired arterial baroreceptors. Arterial ...
Evidence suggests differences between African Americans (AA) and Caucasian Americans (CA) in cardiovascular responsiveness to physiological stressors. This study tested the hypothesis that carotid baroreflex (CBR) control of heart rate (HR) and blood pressure is reduced in AAs compared to CAs during exercise. Mean arterial pressure (MAP) and HR were continuously recorded at rest and during leg cycling in 23 nonhypertensive male subjects (12 AA; 11 CA; age 19-26 yr). CBR control of HR and MAP was assessed with 5-sec pulses of neck pressure (NP, simulated hypotension) and neck suction (NS, simulated hypertension) ranging from +45 to -80 Torr. Across all NS stimuli (-20, -40, -60, -80 Torr) at rest, the AA group demonstrated attenuated CBR-mediated reductions in HR (AA, -8.9 ± 1.9 vs. CA, -14.1 ± 2.3 bpm; P
The reflex responses of fH against changes in blood pressure in tegus were accessed by pharmacological manipulation of arterial pressure, which is a common method of studying baroreflex in vertebrates (Bagshaw, 1985; Altimiras et al., 1998; Crossley et al., 2003; Hagensen et al., 2010). Although this closed-loop study tends to overestimate the reflex sensitivity, it offers the advantages of both being performed with minimal instrumentation on unanaesthetized animals and providing an integrated response caused by activation of all relevant receptors (Altimiras et al., 1998; Crossley et al., 2003; Hagensen et al., 2010). This was an appropriate study to be performed in tegus because the baroreceptor locations as well as their characterization have not previously been demonstrated in these animals.. Even at reduced metabolic rate, suggested by smaller resting fH in our winter tegus, fH baroreflex sensitivity appeared to be preserved. In semi-natural conditions, the abandonment of thermoregulatory ...
TY - JOUR. T1 - Intracoronary epinephrine attenuates baroreflex control of heart rate in the conscious dog. AU - Holmberg, M. J.. AU - Gorman, A. J.. AU - Cornish, K. G.. AU - Zucker, I. H.. PY - 1984. Y1 - 1984. N2 - In the present study, the reflex effects of low-dose (12.5-50 ng·kg-1·min-1) intracoronary epinephrine infusion on the arterial baroreflex control of heart rate were studied. Mean arterial blood pressure-heart rate curves were constructed by changing mean arterial blood pressure with graded occlusions of the descending aorta and inferior vena cava. Intracoronary epinephrine increased left ventricular dP/dt(max) by an average of 309 ± 67.0 mmHg/s but did not alter resting mean arterial blood pressure or heart rate. Peak sensitivity, the maximum absolute slope along the mean arterial blood pressure-heart rate curve, and heart rate range were 32.7 ± 3.2 and 26.7 ± 2.5% less during intracoronary epinephrine compared with control, respectively. Intracoronary epinephrine did not ...
The present study differs from previous reports in several important aspects. In contrast to all previously published studies on idiopathic dilated cardiomyopathy, we investigated the correlation between both baroreflex sensitivity and heart rate variability and several parameters of left ventricular function, including left ventricular ejection fraction and left ventricular end diastolic diameter. Our finding that heart rate variability, baroreflex sensitivity, and left ventricular ejection fraction had only a weak to moderate correlation with each other suggests that they may be of independent prognostic value in patients suffering from idiopathic dilated cardiomyopathy. In contrast to many previous studies, our study investigated a relatively homogeneous group of patients with this disease, all of whom had previously undergone left and right heart catheterisation, including endomyocardial biopsy in 90%. It should be noted that patients on antiarrhythmic drug treatment that could not be ...
The present invention provides systems, devices, and methods for using the same for activating (stimulating) the baroreflex system of a patient using a baroreflex activation system with incrementally changing therapy intensity by sensing/monitoring/interpreting sensed data.
At present, there are insufficient information about baroreflex sensitivity (BRS) and factors that determine BRS in premature newborns. The objective of this study was to determine the relationship between BRS and the characteristics that reflecting the intrauterine development (gestational age and birth weight), as well as postnatal development (postconception age and the actual weight of the child at the time of measurement). We examined 57 premature infants, who were divided into groups according to gestational age and postconception age as well as birth weight, and weight at the time of measurement. Continuous and noninvasive registration of peripheral blood pressure (BP) was performed in every child within 2-5 min under standard conditions using a Portapres (FMS) device. The results showed a close correlation of baroreflex sensitivity, heart rate and respiratory rate with gestational age, postconception age, birth weight and actual weight at the time of measurement premature newborns. An ...
Effect of systolic blood pressure and carotid stiffness on baroreflex gain in elderly subjects. J Gerontol A Biol Sci Med Sci. 2003 Jul; 58(7):626-30 ...
Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the patient, and a processor coupled with the baroreflex activation device(s) and the sensor(s) for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, the system is fully implantable within a patient, such as in an intravascular, extravascular or intramural location.
The important findings of the present study were 1) resting supine MSNA increased after 60 and 120 days of HDBR, 2) the baroreflex slopes for MSNA were augmented after HDBR, in contrast to the attenuated baroreflex control of heart rate, and 3) MSNA increments in response to HUT after HDBR were similar to those before HDBR, but mean blood pressure in 60° HUT decreased after HDBR. The attenuation of baroreflex control of R-R interval after simulated microgravity was consistent with earlier studies (10, 15-17, 19). We emphasize that it may be difficult to manage and reproduce the present experiments due to the long HDBR duration.. In relation to orthostatic hypotension, alterations in peripheral vascular regulation were demonstrated after spaceflight (6, 18, 34). We hypothesized that the baroreflex modulation of vasomotor sympathetic nerve activity, which controls peripheral vascular resistance, may be impaired, and may thus cause a reduction in vasomotor sympathoexcitation, contributing to ...
A method involves implantably detecting changes in posture of a patients body. Baroreflex responses to the posture changes are determined. An autonomic tone of the patient is determined based on the baroreflex responses. Based on the autonomic tone, various patient susceptibilities to disease may be determined, including susceptibilities to heart disease, arrhythmia, and/or sudden cardiac death.
We observed earlier that central alpha-2 adrenoceptor stimulation in mice greatly augments parasympathetic tone. To test the effects in humans, we assessed autonomic vasomotor tone and baroreflex regulation in 9 normal young adults on 2 occasions, on
Abstract Objectives The objective of this clinical trial was to assess the safety and efficacy of carotid BAT in advanced HF. Background Increased sympathetic and decreased parasympathetic activity contribute to heart failure (HF) symptoms and disease progression. Baroreflex activation therapy (BAT) results in centrally mediated reduction of sympathetic outflow and increased parasympathetic activity.
It is well known that the sensitivity of the reflex control of HR in response to vasoactive agents is altered independently by hypertension and by aging in both animal models (27), and in human subjects (22, 26, 49). A consequence of both hypertension and aging is a reduction in vascular distensibility, although the mechanisms are not identical. The demonstration that reduced baroreceptor sensitivity could be accounted for by reduced aortic compliance observed in both aged normotensive rats (5) and hypertensive rats (51), as discussed in the previous section, may provide an explanation for the decreased baroreflex control of HR in hypertensive subjects and aged normotensive humans.. For example, Monahan et al. (43) measured baroreflex control of HR and carotid compliance in 47 healthy sedentary men ranging from 19 to 76 years of age. Monahan and colleagues reported a progressive decline in baroreflex sensitivity with increasing age. The decline in baroreflex sensitivity correlated significantly ...
Bernardi, L., Spadacini, G., Bellwon, J., Hajric, R., Roskamm, H., & Frey, a W. (1998). Effect of breathing rate on oxygen saturation and exercise performance in chronic heart failure. Lancet. S0140-6736(97)10341-5 One month of .1 Hz respiratory training reduces breathing effort and improves both resting pulmonary gas exchange, including enhanced 02 saturation, and exercise performance in patients with chronic heart failure.. Bernardi, L., Porta, C., Spicuzza, L., Bellwon, J., Spadacini, G., Frey, A. W., … Tramarin, R. (2002). Slow breathing increases arterial baroreflex sensitivity in patients with chronic heart failure. Circulation, 105(2), 143-5.. .1 Hz breathing induced highly significant increases in baroreflex sensitivity, beneficial adaptive regulation of blood pressure, both in controls and in chronic heart failure (CHF) patients. In addition to improving oxygen saturation and exercise tolerance, study also demonstrates that spontaneous respiratory rate can be trained with slow ...
We tested whether 6-week vagal stimulation (VS) treatment improved open-loop baroreflex function in rats after myocardial infarction (MI). The following three groups of Sprague-Dawley rats were examined: normal control (NC, n = 9), MI with no treatme
TY - JOUR. T1 - Effect of propranolol on baroreflex arc function essential hypertension. AU - Preston, R. A.. AU - OConnor, D. T.. AU - Mitas, J. A.. AU - Stone, R. A.. PY - 1978/1/1. Y1 - 1978/1/1. UR - http://www.scopus.com/inward/record.url?scp=17944391586&partnerID=8YFLogxK. UR - http://www.scopus.com/inward/citedby.url?scp=17944391586&partnerID=8YFLogxK. M3 - Article. AN - SCOPUS:17944391586. VL - 26. SP - 101A. JO - Journal of Investigative Medicine. JF - Journal of Investigative Medicine. SN - 1081-5589. IS - 2. ER - ...
The purpose of this review is to delineate the general features of endocrine regulation of the baroreceptor reflex as well as specific contributions during pregnancy. the range of sympathetic nerve activity that can be elicited by changes AR-C155858 in arterial pressure. In contrast reductions in the levels or actions of insulin in the brain blunt baroreflex efferent responses to increments or decrements in arterial pressure. Although plasma levels of angiotensin II are increased in pregnancy this is not responsible for the reduction in baroreflex gain although it may contribute to the increased level of sympathetic nerve activity in this condition. How these different hormonal effects are integrated within the Goat polyclonal to IgG (H+L). brain as well as possible interactions with additional potential neuromodulators that influence baroreflex function during pregnancy and other physiological and pathophysiological states remains to be clearly delineated. method that there is much less ...
TY - JOUR. T1 - Autonomic mechanisms and sudden death. T2 - New insights from analysis of baroreceptor reflexes in conscious dogs with and without a myocardial infarction. AU - Schwartz, P. J.. AU - Vanoli, E.. AU - Stramba-Badiale, M.. AU - De Ferrari, G. M.. AU - Billman, G. E.. AU - Foreman, R. D.. PY - 1988. Y1 - 1988. N2 - We have suggested that among conscious dogs with a healed anterior wall myocardial infarction (MI) a depressed baroreflex sensitivity (BRS) carries a high risk of developing ventricular fibrillation during a brief ischemic episode associated with an exercise stress test. The clinical and pathophysiological implications of our previous findings prompted the present study, which addressed three major questions: 1) Is, indeed, analysis of BRS after MI a specific and sensitive marker for sudden death-risk stratification? 2) Does MI modify BRS? 3) Does analysis of BRS before MI provide information about outcoming during ischemic episodes occurring after MI? An anterior MI was ...
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A spontaneous change of plans and the accidental choice of a classic tramping route near Arthurs Pass (December 2018). A long day of hitching and I have made it to the Wanganui River on the West…
Yang Liu, Jia-Ying Zhou, Yu-Hong Zhou, Di Wu, Jian-Li He, Li-Min Han, Xiao-Bo Liang, Lu-Qi Wang, Xiao-Long Lu, Hanying Chen, Guo-Fen Qiao, Weinian Shou and Bai-Yan Li ...
Naturally occurring mutations involving the nervous system have provided virtually all of our current understanding of the genetic regulation of neural development (Caviness and Rakic, 1978). The difficulty of isolating the corresponding genes, however, has precluded a molecular analysis of these mutants. Insertional mutagenesis, induced by microinjection of DNA into fertilized ova to produce transgenic animals, provides a molecular tag that marks the site of the mutational event. In this article, we describe a transgenic neurological mutation, designated wocko (Wo), which disrupts the development of the inner ear. These mutant mice display a dominant behavioral phenotype that consists of circling, hyperactivity, and head tossing, reminiscent of the shaker/waltzer class of mutants, and they display a recessive homozygous sublethal phenotype. Anatomical analyses showed that both structural and neural components of the vestibular system were disrupted, while analyses of mutant fetuses showed that ...
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Synthetic constructs in biotechnology, bio-computing, and proposed gene therapy interventions are often based on plasmids or transfected circuits which implement some form of on-off (toggle or flip-flop) switch. For example, the expression of a protein used for therapeutic purposes might be triggered by the recognition of a specific combination of inducers (e.g., antigens), and memory of this event should be maintained across a cell population until a specific stimulus commands a coordinated shut-off. The robustness of such a design is hampered by molecular (intrinsic) or environmental (extrinsic) noise, which may lead to spontaneous changes of state in a subset of the population and is reflected in the bimodality of protein expression, as measured for example using flow cytometry. In this context, a majority-vote correction circuit, which brings deviant cells back into the required state, is highly desirable. To address this concrete challenge, we have developed a new theoretical design for ...
TY - JOUR. T1 - Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive or spontaneously hypertensive rats. AU - Kawada, Toru. AU - Turner, Michael J.. AU - Shimizu, Shuji. AU - Fukumitsu, Masafumi. AU - Kamiya, Atsunori. AU - Sugimachi, Masaru. PY - 2017/5/30. Y1 - 2017/5/30. N2 - Recent clinical trials in patients with drug-resistant hypertension indicate that electrical activation of the carotid sinus baroreflex (baroreflex activation therapy) can reduce arterial pressure (AP) for more than a year. To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another unstimulated baroreflex system, we electrically stimulated the left aortic depressor nerve (ADN) while estimating the dynamic characteristics of the carotid sinus baroreflex in anesthetized normotensive Wistar-Kyoto (WKY, n=8) rats and spontaneously hypertensive rats (SHR, n=7). Isolated carotid sinus ...
The use of baroreflex stimulation devices (also known as baroreflex activation therapy) is a potential alternative treatment for resistant hypertension and heart failure. Both hypertension and heart failure are relatively common conditions and are initially treated with medications and lifestyle changes. A substantial portion of patients are unresponsive to conventional therapy and treating these patients is often challenging and can lead to high costs and adverse effects. As a result, there is a large unmet need for additional treatments.. New treatment options are being explored to treat drug-resistant hypertension. One such approach is the electrical activation of the carotid sinus baroreflex. Baroreceptors are pressure sensors contained within the walls of the carotid arteries. They are part of the autonomic nervous system that regulates basic physiologic functions such as heart rate and blood pressure (BP). When these receptors are stretched, as occurs with increases in BP, the baroreflex ...
After acute stroke, baroreflex sensitivity (BRS) is impaired. This impaired acute stage BRS has been reported to be predictive of worsen outcome years after stroke in general. However, it is not very clear if the impaired acute stroke BRS would actually persist months after the acute stage. It is also not clear that such change, if any, would correlate with the functional outcome or prognosis after stroke.. The trial is to investigate the longitudinal time course of BRS after ischemic stroke up to the 6th month post stroke and to see if there is any correlation of the changes in BRS with the functional outcome parameters using NIHSS and mRS scores throughout this period. ...
Baroreflex sensitivity (BRS) is an important parameter in the classification of patients with reduced left ventricular function. This study aimed at investigating BRS in patients with dilated cardiomyopathy (DCM) and in healthy subjects (controls), as well as comparing the values of BRS parameters with parameters of heart rate variability (HRV) and blood pressure variability (BPV). ECG, continuous blood pressure and respiration curves were recorded for 30min in 27 DCM patients and 27 control subjects. The Dual Sequence Method (DSM) includes the analysis of spontaneous fluctuations in systolic blood pressure and the corresponding beat-to-beat intervals of heart rate to estimate bradycardic, opposite tachycardic and delayed baroreflex fluctuations. The number of systolic blood pressure/beat-to-beat interval fluctuations in DCM patients was reduced in comparison with controls (DCM patients: male, 154.4±93.9ms/mmHg; female, 93.7±40.5ms/mmHg; controls: male, 245.5±112.9ms/mmHg; female, ...
The complete arterial baroreceptor reflex pathway is a control system made up of two distinct portions as shown in Figure E-1: (1) an effector portion, including the heart and peripheral blood vessels, and (2) a neural portion, including the arterial baroreceptors, their afferent nerve fibers, the medullary cardiovascular centers, and the efferent sympathetic and parasympathetic fibers. Mean arterial pressure is the output of the effector portion and simultaneously the input to the neural portion. Similarly, the activity of the sympathetic (and parasympathetic) cardiovascular nerves is the output of the neural portion of the arterial baroreceptor control system and, at the same time, the input to the effector portion. For convenience, we omit continual reference to parasympathetic nerve activity in the following discussion. Throughout, however, an indicated change in sympathetic nerve activity should usually be taken to imply a reciprocal change in the activity of the cardiac parasympathetic ...
Previous studies have provided both direct and indirect evidence for a functional role of α7-containing receptors in autonomic function at the cellular level. Studies in α7-deficient mice have indicated that baroreflex stimulation of the parasympathetic limb does not display altered parasympathetic function but that stimulation of the sympathetic limb demonstrates abnormal sympathetic responses (7). The possibility has remained, however, that α7-subunits play a role in resting autonomic tone rather than in stimulated activity, and the possibility of some modulatory role on autonomic function has remained. In this study, we have shown that the α7-nAChR subunit is not required for parasympathetic modulation of HR in the resting state or under artificial controlled stimulation of vagal pathways to the heart throughout a wide stimulation range.. Resting HR and PSD profiles were not significantly different between the groups of mice, suggesting that either the α7-subunit does not play a role in ...
My name is Dale and I was recently diagnosed with POTS by Dr. Julian Stewart at the center for hypotension in New York. I participated in his CFS/POTS study because I was diagnosed with Chronic Fatigue Syndrome when I was 19 at The Mayo Clinic flollowing a one year Chronic EBV infection.Ill be 26 this year. He said I had some very unusual findings and some of the most peculiar data seen so far in such patients. I have a normal BMI but appear thin. During H.U.T. I had a 30 percent reduction of cerebral blood flow to my brain which was associated with a large degree of hypocapnia. Hr increased to over 130bmp. Heart rate variability was abnormal with increased low frequency peaks suggesting sympathhetic activation even supine.Blood pressure variability was also increased suggesting accentuated supine sympathetic baroreflex. Arm blood flows were high but leg blood flows measured by venous occlusion plethysmography were reduced and I may have the lowest blood pressure in my legs that hes ever seen. ...
Overview Todays lecture is 50 minutes long. http://www.youtube.com/watch?v=srjNMMtPATo Details The direction of spontaneous change is related to G. 2nd law dS|dq/T for spontaneous change 1st law dU = dq + dW The basic thermodynamic quantities are H, A, G and U. There are the fundamental equations. Everything is in terms of state variables. Path doesnt…
Low rates of Absorb BRS thrombosis beyond 12 months in patients treated with aggressive pre- and post-dilatation using highly non-compliant ...
α 1. Vagus Nerve. Baroreflex. M2(-). B1(+). ANP. ATII. B1. Renin. Constrict. ADH. Aldosterone. Slideshow 6856107 by henry-bernard
金 秀吉 , 河南 洋 , 林田 嘉朗 , 中村 正 , 東野 英明 , 山下 博 産業医科大学雑誌 11, 361-370, 1989 医中誌Web 被引用文献1件 ...
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Study Flashcards On BRS Phys 1 Cell Physiology at Cram.com. Quickly memorize the terms, phrases and much more. Cram.com makes it easy to get the grade you want!
We examined the ANS in PD patients using a new method which can more directly investigate the function of the baroreflex by ... We examined the ANS in PD patients using a new method which can more directly investigate the function of the baroreflex by ... We examined the ANS in PD patients using a new method which can more directly investigate the function of the baroreflex by ... We examined the ANS in PD patients using a new method which can more directly investigate the function of the baroreflex by ...
... and baroreflex sensitivity we show that decreased vagal function is associated with an increased risk for morbidity and ...
Angiotensin II-dependent hypertension and the arterial baroreflex. Bishop VS, Ryuzaki M, Cai Y, Nishida Y, Cox BF. Bishop VS, ...
Baroreflex Activation Therapy for the Treatment of Heart Failure with a Reduced Ejection Fraction ...
... with advanced heart failure who are not suited for other heart failure devices by electrically activating the baroreflex to ...
Jeff Ratliff discusses the natural history of afferent baroreflex failure with Dr. Guillaume Lamotte. ...
Yoga Practitioners Exhibit Higher Parasympathetic Activity and Baroreflex Sensitivity and Better Adaptability to 40 mm Hg Lower ...
keywords = "Autonomic, Baroreceptor, Baroreflex, Blood pressure, Piezo",. author = "Stocker, {Sean D.} and Sved, {Alan F.} and ...
abortus Bang ring [test]; • absolute bed rest; • American Board of Radiology; • arterial baroreflex; • auditory brainstem ...
Bell, K. R., Fann, J. R., Brockway, J. A., Cole, W. R., Bush, N. E., Dikmen, S., Hart, T., Lang, A. J., Grant, G., Gahm, G., Reger, M. A., St De Lore, J., Machamer, J., Ernstrom, K., Raman, R., Jain, S., Stein, M. B. & Temkin, N., Jan 15 2017, In: Journal of neurotrauma. 34, 2, p. 313-321 9 p.. Research output: Contribution to journal › Article › peer-review ...
Seifert, S. A., Buckley, N., Chan, B., Chan, T. Y. K., Cumpston, K., Kirschner, R. I., Megarbane, B., Mullins, M., Seger, D., Thomas, S., Vale, J. A. & Wilks, M. F., Mar 1 2021, In: Clinical toxicology (Philadelphia, Pa.). 59, 3, p. e1-e3. Research output: Contribution to journal › Article › peer-review ...
Formula 9: Five-parameter baroreflex model (baro5):. Calculation of measures for goodness-of-fit. For each simulation, we ...
3rd place: Ida T. Fonkoue, PhD (Emory University): Impaired Arterial Baroreflex Sensitivity in Prehypertention ...
Modelling of the baroreflex-feedback mechanism with time-delay. JT Ottesen. Journal of mathematical biology 36 (1), 41-63, 1997 ... Modeling baroreflex regulation of heart rate during orthostatic stress. MS Olufsen, HT Tran, JT Ottesen, LA Lipsitz, V Novak ... Modeling the afferent dynamics of the baroreflex control system. A Mahdi, J Sturdy, JT Ottesen, MS Olufsen ...
Modeling baroreflex regulation of heart rate during orthostatic stress MS Olufsen, HT Tran, JT Ottesen, LA Lipsitz, V Novak ...
This is suggested to be related to changes in baroreflex sensitivity.. The same group found a large percentage of non- ...
Baroreflex sensitivity and heart rate variability in the identification of patients at risk for life-threatening arrhythmias: ... Arterial baroreflex sensitivity assessed from phase IV of the Valsalva maneuver. Am J Cardiol 1996; 78: 575-579. ... Arterial baroreflex modulation of heart rate in chronic heart failure: Clinical and hemodynamic correlates and prognostic ... La Rovere MT, Pinna GD, Mortara A. Assessment of baroreflex sensitivity. In: Malik M (ed). Clinical Guide to Cardiac Autonomic ...
Provides 100% compliance to treatment, by automatically and continuously activating the baroreflex. ...
Armelin, V. A., Braga, V. H. D. S., Teixeira, M. T., Guagnoni, I. N., Wang, T. & Florindo, L. H. (2021). The baroreflex in ... Does terrestriality represent a significant driving force for the evolution of a more effective baroreflex in vertebrates? ... The nonpharmacological sequence method provides a reliable evaluation of baroreflex sensitivity in fish. Journal of ...
Baroreflex Activation Therapy for the Treatment of HFrEF - When CRT Is Not an Option ...
The increase in baroreflex sensitivity correlated significantly with the mean depth of PPN stimulating electrode contacts. This ... presumably by altering the neural control of baroreflex activation. ... Baroreflex sensitivity increased during Valsalva compared to rest with stimulation ON versus OFF (p = 0.028). ... Baroreflex sensitivity increased during Valsalva compared to rest with stimulation ON versus OFF (p = 0.028). The increase in ...
... while the heart rate is regulated with a baroreflex model. With this computer model, both normal and heart failure hemodynamics ... while the heart rate is regulated with a baroreflex model. With this computer model, both normal and heart failure hemodynamics ... while the heart rate is regulated with a baroreflex model. With this computer model, both normal and heart failure hemodynamics ... while the heart rate is regulated with a baroreflex model. With this computer model, both normal and heart failure hemodynamics ...
Impairment in baroreflex sensitivity in recent-onset type 2 diabetes without progression over 5 years. Diabetes. 69(5):1011- ...
The frequency of sbp/dbp baroreflex responses before ivermectin in pill form for humans and during lisinopril. This website has ...
SMT augmente haute fréquence de la VRC (modulation parasympathique cardiaque) et la sensibilité des baroreflexes. (pas de diff ...
In contrast, significant baroreflex sensitivity for diastolic pressure and cardiac interval was present in only 55 and 73% of ... In contrast, significant baroreflex sensitivity in both periods was present in only 30% (diastolic pressure) and 40% (cardiac ... The results were expressed as blood pressure/cardiac interval threshold for occurrence of bursts, and as baroreflex sensitivity ... 4. The results show that the baroreflex mechanisms regulating the occurrence and strength of sympathetic bursts are not ...
It reported that by praying the rosary or reciting yoga mantras at specific rates, baroreflex sensitivity increased ...
  • 9 . The method of claim 1 , wherein determining the autonomic imbalance of the patient comprises performing a baroreflex sensitivity analysis (BSA) based on blood pressure and cardiac signals measured during a time period corresponding to the posture change. (google.com)
  • The objective of the present study was to investigate the effects of an acute aerobic exercise on arterial pressure (AP), heart rate (HR), and baroreflex sensitivity (BRS) in STZ-induced diabetic rats. (hindawi.com)
  • 14 ] have demonstrated that 12 months of exercise training applied to type 2 diabetic patients without autonomic neuropathy-induced improvement in baroreflex sensitivity (BRS). (hindawi.com)
  • In the aging process, a decline in baroreflex sensitivity (BRS) is expected ( 9 , 10 ). (scielo.br)
  • Baroreflex sensitivity (i.e., the capability of the autonomic nervous system to detect and respond efficaciously to acute changes in blood pressure) has been recognized as having predictive value for cardiovascular events as well as playing a role in effective short-term regulation of blood pressure. (biomedsearch.com)
  • Future studies are needed to describe whether dysfunctional baroreflex sensitivity after SCI is due to arterial stiffening or a neural component. (biomedsearch.com)
  • Further, measurement of forearm vascular conductance and/or muscle sympathetic nerve activity is required to directly evaluate of the sensitivity of the sympathetic arm of the baroreflex in those with SCI. (biomedsearch.com)
  • The effect of long-term nocturnal therapy with continuous positive airway pressure (CPAP) on daytime baroreflex sensitivity (BRS), a predictor of cardiac death, was investigated in OSAS patients. (clinicaltrials.gov)
  • Changes in RR-interval and MSA, evoked by sodium nitroprusside-induced reduction of BP, were used to quantitate baroreflex sensitivity. (nih.gov)
  • Both the cardiac (expressed as the RR-interval versus mean arterial BP slope) and the muscle sympathetic (mean MSA area versus diastolic BP slope) baroreflex sensitivity were depressed in patients as compared with controls. (nih.gov)
  • 0.025) baroreflex sensitivity in the entire study group. (nih.gov)
  • We conclude that OSA patients exhibit an impaired baroreflex sensitivity to a hypotensive stimulus, which may represent an adaptive response to changes in BP or hypoxemia occurring in association with nocturnal apneas. (nih.gov)
  • We tested how different types of seizures affect baroreflex sensitivity (BRS) and heart rate variability (HRV). (frontiersin.org)
  • Background - It is well established that a depressed baroreflex sensitivity may adversely influence the prognosis in patients with chronic heart failure (CHF) and in those with previous myocardial infarction. (ahajournals.org)
  • Conclusions - These data suggest that in patients with CHF, slow breathing, in addition to improving oxygen saturation and exercise tolerance as has been previously shown, may be beneficial by increasing baroreflex sensitivity. (ahajournals.org)
  • 8 Whether slow breathing has any effect on arterial baroreflex sensitivity in heart failure, however, is still unknown. (ahajournals.org)
  • Arterial baroreflex sensitivity was measured by spectral analysis using the "α-angle" method. (ahajournals.org)
  • OBJECTIVE To examine the relation between cardiac autonomic tone, assessed by baroreflex sensitivity and heart rate variability, and left ventricular function, arrhythmias on Holter monitoring, and clinical variables in patients with idiopathic dilated cardiomyopathy. (bmj.com)
  • Baroreflex sensitivity testing was performed using the phenylephrine method. (bmj.com)
  • RESULTS Mean SDNN (SEM) was 112 (46) ms, and baroreflex sensitivity was 7.5 (5.0) ms/mm Hg. (bmj.com)
  • In addition, baroreflex sensitivity showed no significant correlation with age ( r = −0.13), non-sustained ventricular tachycardia ( r = −0.08), left ventricular end diastolic diameter ( r = 0.09), or ejection fraction ( r = 0.14). (bmj.com)
  • CONCLUSIONS The weak correlation between baroreflex sensitivity and heart rate variability suggests that these two indices explore different aspects of cardiac autonomic control in patients with idiopathic dilated cardiomyopathy. (bmj.com)
  • The weak or absent correlation between baroreflex sensitivity, heart rate variability, and other potential non-invasive risk predictors, including left ventricular ejection fraction, left ventricular end diastolic diameter, and non-sustained ventricular tachycardia on Holter monitoring, indicate that these variables may have independent prognostic value in idiopathic dilated cardiomyopathy. (bmj.com)
  • the second is the examination of baroreflex sensitivity as a measure of reflex autonomic response. (bmj.com)
  • Recently, it has been reported that decreased baroreflex sensitivity and reduced heart rate variability are associated with an adverse prognosis in patients after myocardial infarction. (bmj.com)
  • Prognostic value of baroreflex sensitivity testing after acute myocardial infarction. (bmj.com)
  • METHODS--As part of a prospective trial of risk stratification in post-infarction patients arterial baroreflex sensitivity, heart rate variability, long term electrocardiographic recordings, exercise stress testing, and ejection fraction were recorded between days 7 and 10 in 122 patients with acute myocardial infarction. (bmj.com)
  • Baroreflex sensitivity was appreciably reduced in these patients suffering arrhythmic events (1.73 SD (1.49) v 7.83 (4.5) ms/mm hg, 95% confidence interval (CI) 4.8 to 7.3, p = 0.0001). (bmj.com)
  • When baroreflex sensitivity was adjusted for the effects of age and ventricular function baroreflex sensitivity was still considerably reduced in the arrhythmic group (2.1 v 7.57 ms/mm Hg, p less than 0.0001). (bmj.com)
  • Depressed baroreflex sensitivity carried the highest relative risk for arrhythmic events (23.1, 95% CI 7.7 to 69.2) and was superior to other prognostic variables including left ventricular function (10.4, 95% CI 3.3 to 32.6) and heart rate variability (10.1, 95% CI 5.6 to 18.1). (bmj.com)
  • CONCLUSIONS--Disordered autonomic function as measured by depressed baroreflex sensitivity or reduced heart rate variability was associated with an increase incidence of arrhythmic events in post-infarction patients. (bmj.com)
  • In 26 normotensive and normoweight prediabetic patients, aged 45.2 ± 3.2 years (mean ± SEM), we assessed efferent postganglionic muscle sympathetic nerve traffic (MSNA, microneurography), spontaneous baroreflex sensitivity, and a number of hemodynamic and metabolic variables, including homeostatic model assessment (HOMA) index. (ovid.com)
  • This neurogenic abnormality was associated with a reduced spontaneous baroreflex MSNA sensitivity (−3.20 ± 0.2 vs. −4.72 ± 0.2 a.u. (ovid.com)
  • In the multivariate analysis, performed in prediabetic patients, MSNA values were directly and significantly related to HOMA index and inversely and significantly to baroreflex-MSNA sensitivity. (ovid.com)
  • This can be due to the consequences of an increased insulin sensitivity but also to a restoration of the baroreflex control of the cardiovascular system with weight loss. (ahajournals.org)
  • As they age, Sprague-Dawley (SD) rats develop elevated systolic blood pressure associated with impaired baroreflex sensitivity (BRS) for control of heart rate. (rti.org)
  • In the present study, the effect of chronic administration of kefir on the cardiac autonomic control of heart rate (HR) and baroreflex sensitivity (BRS) in SHR was evaluated. (frontiersin.org)
  • Decreased spontaneous cardiac baroreflex sensitivity (BRS), which could lead to the onset of cardiovascular events, has been demonstrated in chronic obstructive pulmonary disease patients. (ersjournals.com)
  • It is concluded that, in chronic obstructive pulmonary disease patients, exercise training is associated with a gain in spontaneous baroreflex sensitivity, reflecting cardiovascular benefits. (ersjournals.com)
  • 6 first demonstrated decreased pharmacological baroreflex sensitivity (BRS) in 27 COPD patients compared to controls and a significant negative relationship with mean pulmonary arterial pressure. (ersjournals.com)
  • After acute stroke, baroreflex sensitivity (BRS) is impaired. (centerwatch.com)
  • A few studies have suggested an association between prenatal exposure to methylmercury and decreased heart rate variability (HRV) related to autonomic heart function, but no study has examined this association using baroreflex sensitivity (BRS). (mdpi.com)
  • Both abnormal autonomic control of heart rate, assessed by heart rate variability (HRV) and baroreflex sensitivity (BRS), and insulin resistance syndrome are common in hypertensive patients. (nih.gov)
  • Arterialcardiac-chronotropic baroreflex sensitivity (ABS) was assessed as the ratio between tilt-induced heart rate transients and the preceding (and reciprocal) transient in arterial pressure. (diva-portal.org)
  • In these patients, repetitive nocturnal OSA-related surges in BP, associated with recurrent hypoxia, arousals from sleep, activation of the sympathetic nervous system and impaired baroreflex sensitivity (BRS) for heart rate, could contribute to the development or progression of hypertension 8 , 9 . (ersjournals.com)
  • Cardiopulmonary baroreflex sympathetic sensitivity, which was derived as the slope of the linear regression relation between percent change in total MSNA (units) per absolute change in central venous pressure (mm Hg) during incremental LBNP, was significantly augmented after both the high dose (from 18.6 +/- 4.7%/mm Hg to 39.3 +/- 8.1%/mm Hg, p = 0.001) and low dose of naloxone, whereas placebo had no effect. (ahajournals.org)
  • To better understand the relationship between the brain renin-angiotensin system (RAS) and endocannabinoid expression within the NTS, we measured dorsal medullary endocannabinoid tissue content and the effects of CB1 receptor blockade at this brain site on cardiac baroreflex sensitivity (BRS) in ASrAOGEN rats with low glial angiotensinogen, normal Sprague-Dawley rats and (mRen2)27 rats with upregulated brain RAS expression. (rti.org)
  • The invention relates to a method for deter the baroreflex latent period, and particularly the corresponding baroreflex sensitivity. (google.com)
  • Rosiglitazone normalizes BRG, but not by improving brain baroreflex processing or insulin sensitivity. (aspetjournals.org)
  • OBJECTIVES To evaluate spontaneous blood pressure and heart rate variability and spontaneous baroreflex sensitivity before and after brain death. (bmj.com)
  • METHODS Spontaneous variability of arterial blood pressure and heart rate-estimated by power spectra of systolic (SBP) and diastolic blood pressure (DBP) and pulse interval (PI)-and spontaneous baroreflex sensitivity (BRS)-estimated by the alpha index and the sequence technique-were evaluated in 11 patients twice: shortly before and 1 hour after the onset of brain death. (bmj.com)
  • These findings indicate that techniques of blood pressure and heart rate spectral analysis and of dynamic assessment of baroreflex sensitivity may be useful to complement the diagnosis of brain stem death. (bmj.com)
  • 4. In both normotensive and hypertensive subjects standard deviation and even more so variation coefficient were slightly or not related to arterial baroreflex sensitivity as measured by various methods (phenylephrine, neck suction etc. (portlandpress.com)
  • Heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) are relevant predictors of cardiovascular risk in humans. (hu-berlin.de)
  • Baroreflex sensitivity during hyperthermia and central hypovolemia. (wku.edu)
  • This study tested the hypothesis that baroreflex sensitivity (as indexed from ∆ heart rate /∆ blood pressure) would be reduced in hyperthermia compared to normothermia during central hypovolemia. (wku.edu)
  • Baroreflex sensitivity was assessed during the final full stage of LBNP completed, and during a 30 second period immediately preceding any bradycardia prior to pre-syncope. (wku.edu)
  • 15 A reduction in sympathetic baroreflex sensitivity (BRS) results in greater hemodynamic liability when the patient is challenged with hypotension, hemorrhage, or general anesthesia. (asahq.org)
  • Subnormal baroreflex sensitivity (BRS) is an important risk indicator for sudden death. (onlinejacc.org)
  • Because abrupt occlusion of a coronary artery is a major cause of sudden cardiac death (13) and experimental studies suggest that low baroreflex sensitivity (BRS) is a marker of increased risk of ventricular fibrillation during acute coronary occlusion (14-16) , we assessed the effects of acute coronary occlusion on baroreflex control of the circulation in a prospective series of patients undergoing clinically indicated coronary angioplasty. (onlinejacc.org)
  • Carotid artery baroreflex sensitivity was assessed by measuring the in RR interval during manipulation of carotid artery transmural pressure. (onlinejacc.org)
  • To investigate the effects of an oral glucose tolerance test (OGTT) on baroreflex sensitivity (BRS) in a sample of healthy adolescents, and how acute exercise bouts of different intensities alter the effects of the OGTT on BRS. (springer.com)
  • 2001 ). A sentinel for hypertension development is decreased baroreflex sensitivity (BRS). (springer.com)
  • Baroreflex sensitivity is composed of autonomic and vascular components which contribute towards the beat-to-beat detection and adjustment of blood pressure fluctuations (Hunt et al. (springer.com)
  • We measured the changes from baseline mean arterial pressure, renal plasma flow, plasma renin activity, aldosterone, urine sodium, and baroreflex sensitivity in both groups. (ahajournals.org)
  • The spontaneous baroreflex sensitivity at baseline was significantly lower in patients with POTS compared with controls (10.1±1.2 versus 16.8±1.5 ms/mm Hg, P =0.003), and it was further reduced with Ang II infusion. (ahajournals.org)
  • In TSG compared to TSW, CW, and CG groups, baroreflex sensitivity of heart rate (BSHR) and renal nerve activity (BSRA) were significantly decreased. (springer.com)
  • Baroreflex sensitivity in premature infants - relation to the parameters characterizing intrauterine and postnatal condition. (physiciansweekly.com)
  • At present, there are insufficient information about baroreflex sensitivity (BRS) and factors that determine BRS in premature newborns. (physiciansweekly.com)
  • The results showed a close correlation of baroreflex sensitivity, heart rate and respiratory rate with gestational age, postconception age, birth weight and actual weight at the time of measurement premature newborns. (physiciansweekly.com)
  • Baroreflex sensitivity in the first week was in the group of very premature newborns the lowest (4.11 ms/mmHg) and in the light premature newborns was almost double (8.12 ms/mmHg). (physiciansweekly.com)
  • The baseline values of baroreflex sensitivity (BRS) of HR evaluated by the sequence method were similar in both groups. (nii.ac.jp)
  • Our first hypothesis was that a steady pattern could be associated with reduced baroreflex sensitivity and HF-RR amplitude, reflecting a blunted autonomic nervous function. (inserm.fr)
  • Our second hypothesis was that PEEP, widely used in critical care patients, could affect their autonomic function, promoting both steady pattern and reduced baroreflex sensitivity. (inserm.fr)
  • Cross-spectral analysis was used to assess the coherence and gain functions between RR and SBP, yielding baroreflex-sensitivity indices. (inserm.fr)
  • Selective vagal denervation of the atria eliminates heart rate variability and baroreflex sensitivity while preserving ventricular innervation. (semanticscholar.org)
  • article{Chiou1998SelectiveVD, title={Selective vagal denervation of the atria eliminates heart rate variability and baroreflex sensitivity while preserving ventricular innervation. (semanticscholar.org)
  • Patients with hypertension have a blunted sensitivity of baroreflex control of heart period. (elsevier.com)
  • In these patients, baroreflex sensitivity is positively related to heart rate variability and inversely related to blood pressure variability. (elsevier.com)
  • We hypothesized that this relationship would also be evident in healthy normotensive subjects and that individuals with higher baroreflex sensitivity would have lower ambulatory 24-hour blood pressure. (elsevier.com)
  • The baroreflex was assessed using sequential bolus administration of sodium nitroprusside and phenylephrine, and baroreflex sensitivity was calculated as the slope of the relation between systolic blood pressure and R-R interval during the resulting blood pressure transients. (elsevier.com)
  • In contrast, no relationship was found between baroreflex sensitivity and 24-hour heart rate or blood pressure variabilities. (elsevier.com)
  • We conclude that the relationship between baroreflex sensitivity and daytime heart rate variability was similar to that reported previously in hypertensive subjects. (elsevier.com)
  • Furthermore, the inverse relation between baroreflex sensitivity and mean arterial pressure supports the idea that the baroreflex may exert longer-term effects on blood pressure than thought previously. (elsevier.com)
  • Eisenach, John H. / Baroreflex sensitivity inversely correlates with ambulatory blood pressure in healthy normotensive humans . (elsevier.com)
  • What is the effect of treatment with the antihypertensive agents lisinopril and labetalol on baroreflex sensitivity (BRS) in patients with previous stroke or transient ischaemic attack (TIA)? (isrctn.com)
  • Our hypothesis is that treatment with the antihypertensive agents lisinopril and labetalol produces an improvement in baroreflex sensitivity in stroke patients. (isrctn.com)
  • Autonomic impairment , as measured by heart rate variability and baroreflex sensitivity, is significantly associated with increased mortality after traumatic brain injury . (operativeneurosurgery.com)
  • Continuous measurements of heart rate variability and baroreflex sensitivity in the neuromonitoring setting of severe traumatic brain injury may carry novel pathophysiological and predictive information 1) . (operativeneurosurgery.com)
  • Cervical vagal stimulation for 2 h results in a depressed baroreflex sensitivity produced by an enhanced sympathetic output, as indicated by increased plasma norepinephrine levels. (islandscholar.ca)
  • The current study examined the role of the insular cortex in modulating the vagal stimulation-induced changes in baroreflex sensitivity. (islandscholar.ca)
  • Male Sprague-Dawley rats were anesthetized with thiobutabarbitol sodium and instrumented for recording blood pressure, heart rate, intravenous drug administration, and vagal afferent Show more Cervical vagal stimulation for 2 h results in a depressed baroreflex sensitivity produced by an enhanced sympathetic output, as indicated by increased plasma norepinephrine levels. (islandscholar.ca)
  • We adapted telemetry and sequence analysis employed in humans to mice and measured heart rate variability and the spontaneous baroreflex sensitivity in angiotensin II type 2 (AT2) receptor-deleted (AT2 -/-) and wild-type (AT2 +/+) mice with either deoxycorticosterone acetate (DOCA)-salt hypertension or Nw-nitro-L-arginine methylester hydrochloride (L-NAME) hypertension. (mdc-berlin.de)
  • As the arterial baroreflex importantly contributes to modulation of the autonomic influences on the heart and thereby arrhythmogenesis, baroreflex sensitivity has been used as a measure of the interaction between sympathetic and parasympathetic activities at the cardiac level. (elsevier.com)
  • Baroreflex sensitivity is expressed as ms/mmHg and prevailing vagal reflexes are reflected by the wider R-R interval lengthening. (elsevier.com)
  • The experimental evidence that the occurrence of ventricular fibrillation was inversely related to baroreflex sensitivity, opened the way to clinical studies. (elsevier.com)
  • The value of a depressed baroreflex sensitivity as a risk stratifier is meaningful in patients below age 65 in combination of a simultaneously depressed left ventricular ejection fraction. (elsevier.com)
  • La Rovere, MT 2000, ' Baroreflex sensitivity as a new marker for risk stratification ', Zeitschrift fur Kardiologie , vol. 89, no. (elsevier.com)
  • Time-domain HRV parameters, frequency domain HR and systolic BP variability parameters, and baroreflex sensitivity (sequence technique) were computed from Finometer- and EndoPAT-derived time series and intraclass correlation coefficients (ICC) were calculated. (biomedcentral.com)
  • Baroreflex sensitivity: population values. (ox.ac.uk)
  • RESEARCH DESIGN AND METHODS In 14 patients with type 2 diabetes without autonomic complications, we measured blood pressure, heart rate, oxygen saturation, chemoreflex (hypoxic and hypercapnic ventilatory responses, ventilatory recruitment threshold), and baroreflex sensitivity before, immediately after, and 3 and 6 h after a 1-h single bout of IH (6-min breathing of 13% oxygen mixture 5 times each separated by 6-min recovery). (diabetesjournals.org)
  • RESULTS IH significantly increased hypercapnic ventilatory responses and reduced ventilatory recruitment threshold, and increased oxygen saturation and blood pressures, whereas increases in heart rate variability and baroreflex sensitivity were not significant. (diabetesjournals.org)
  • The baroreflex sensitivity was examined during intravenous injection of phenylephrine (PE) or sodium nitroprusside (SNP) and quantified by the change in heart rate over the change in mean arterial blood pressure (ΔHR/ΔMABP). (biomedcentral.com)
  • Therefore, it is essential to develop alternative drugs to prevent the blunted baroreflex sensitivity induced by DM. (biomedcentral.com)
  • Inhibition of cardiac baroreflex sensitivity after central dopaminergic stimulation. (edu.au)
  • 2. In the present study, this treatment produced a significant decrease of cardiac baroreflex sensitivity in conscious rats. (edu.au)
  • 3. The central dopamine-mediated decrease in baroreflex sensitivity may be involved in functionally potentiating the circulatory actions of vasopressin. (edu.au)
  • Should we still use nitrovasodilators to test baroreflex sensitivity? (ox.ac.uk)
  • 1. Baroreflex sensitivity was studied in relation to the development of spontaneous hypertension in rats (SH rats), with normotensive Wistar-Kyoto (WKY) rats as controls. (meta.org)
  • Baroreflex sensitivity did not differ at this age (0.37 +/- 0.04 vs 0.38 +/- 0.05 ms/mmHg). (meta.org)
  • Baroreflex sensitivity did not change during development of SH rats (0.40 +/- 0.03 ms/mmHg in 12-20 weeks old SH rats), whereas it increased two- to three-fold in WKY rats (0.93 +/- 0.08 ms/mmHg, P less than 0.001). (meta.org)
  • 4. It is concluded that an increase in baroreflex sensitivity is part of the development of a normotensive cardiovascular system, whereas in SH rats responsiveness of the baroreceptor reflex remain. (meta.org)
  • ABR function is often measured by the size of the baroreflex sensitivity (BRS). (dissertationtopic.net)
  • Cardiac autonomic activities were evaluated by measuring baroreflex sensitivity (BRS). (elsevier.com)
  • Previous studies showed that a proportion of normotensive Sprague-Dawley rats spontaneously exhibit lower baroreflex sensitivity. (touchcardio.com)
  • We aimed to compare baroreflex sensitivity among rats from the same strain and the same laboratory. (touchcardio.com)
  • There was a significant change in baroreflex sensitivity among rats from the same strain and the same laboratory. (touchcardio.com)
  • High-renin hypertensive rats showed overactivity of the renin angiotensin system and a great depression of the baroreflexes, comparable to the depression observed in chronic sinoaortic denervated rats. (scielo.br)
  • Moreover, in OP rats, stimulation of the aortic depressor nerve, to activate central baroreflex pathways, elicited markedly reduced decreases in heart rate and arterial pressure, but these responses were not improved by rosiglitazone. (aspetjournals.org)
  • A comparison of the baroreflex function curves in untreated SHR and SHRSP showed that the vagal component of the heart rate range was markedly reduced compared to that in WKY rats. (ovid.com)
  • With perindopril from the age of 4 to 14 weeks, the vagal baroreflex heart rate range was similar to that of WKY rats. (ovid.com)
  • These data suggest that in adult female rats that are perinatally supplemented with taurine, high sugar intake after weaning blunts arterial baroreflex via an estrogen (but not renin-angiotensin) mechanism. (springer.com)
  • Baroreflex buffering of pressor response to vasopressin is mediated by V1, not V2, receptors in conscious rats. (semanticscholar.org)
  • This study was designed to elucidate the effects of DMC on baroreflexes in streptozocin (STZ)-induced diabetic rats with hyperlipoidemia. (biomedcentral.com)
  • The Daming capsule partially reversed the parasympathetic baroreflex impairment observed in STZ-induced diabetic rats with hyperlipoidemia. (biomedcentral.com)
  • The aim of the present study was, therefore, to determine the effects of emotional stress on the sympathetic baroreflex in conscious rats. (edu.lb)
  • In conclusion, the baroreflex control of RSNA is sensitized and operates over a larger range during emotional stress in rats, which suggests that renal vascular tone, and possibly AP, are very efficiently controlled by the sympathetic nervous system under this condition. (edu.lb)
  • These results suggest that vestibular stimulation associated with head movements in yaw inhibits vagally mediated baroreflex control of heart rate, whereas oculomotor stimulation is less of a factor and only in the absence of vestibular stimulation. (physiology.org)
  • An example of physiological mechanisms for cardiovascular homeostasis is the baroreflex. (scielo.br)
  • An example of a physiological mechanism for cardiovascular control is the baroreflex ( 7 ). (scielo.br)
  • As recently reviewed [ 3 ], conditions of exaggerated and sustained sympathetic activity, reduced parasympathetic activity, and baroreflex dysfunction are important cardiovascular risks. (hindawi.com)
  • The baroreflex, a cardiovascular feedback control mechanism devoted to the maintenance of circulatory homeostasis, reflects autonomic control mediated by medullary autonomic neural circuits ( 5 ). (frontiersin.org)
  • Background -Previous studies have shown that sympathetic cardiovascular outflow is increased in obese normotensive subjects and that this increase is associated with a baroreflex impairment. (ahajournals.org)
  • We sought to determine whether the cardiovascular deconditioning that occurs in exercising men after prolonged (42 days) bedrest in the head-down tilt (HDT) position is primarily related to mechanical changes in the heart or to an impaired arterial-cardiacchronotropic baroreflex. (diva-portal.org)
  • Our results indicate that impairments of the cardiovascular system after long-term bedrest are of haemodynamic rather than baroreflex origin. (diva-portal.org)
  • The arterial baroreflex may be the most important of the cardiovascular control mechanisms, because the baroreflex, above all other reflex mechanisms is the one whose speed is most adequate to respond rapidly to the abrupt transients of arterial pressure that occur in daily life. (booktopia.com.au)
  • Arterial baroreflex is an important short-term neural control mechanism that maintains cardiovascular stability. (asahq.org)
  • Subsequently, a catheter was inserted into the femoral artery, for cardiovascular recordings, and into the femoral vein for assessing baroreflex activation. (deepdyve.com)
  • Positive end-expiratory pressure may alter breathing cardiovascular variability and baroreflex gain in mechanically ventilated patients. (inserm.fr)
  • This will be followed by an analysis of the effects of 1) the hyperadrenergic state on the cardiovascular risk profile as well as on the end organ damage and 2) the different antihypertensive compounds on sympathetic and baroreflex function. (eurekaselect.com)
  • Importantly, lower levels of cardiovagal baroreflex have been associated with poor orthostatic tolerance and an increased cardiovascular disease-related mortality. (vt.edu)
  • Traditional cardiovascular autonomic control markers were assessed along with a Granger causality index assessing the strength of the causal relation from SAP to HP (CRSAP→HP) and measuring the degree of involvement of the cardiac baroreflex. (phoenixrising.me)
  • Remarkably, the association between the strength of the baroreflex involvement and the FIQ score was not detected at REST, thus stressing the importance of challenging cardiovascular control to evoke meaningful responses useful for clinical purposes. (phoenixrising.me)
  • Review the role of the baroreflex as a primary regulator of cardiovascular function and have a better understanding of the mode of action. (radcliffecardiology.com)
  • Closed-loop neuromodulation technology focusing on arterial baroreflex is challenging and might be promising to tackle the pathogenesis of blood pressure-related disorders, autonomic dysregulation, and eventually cardiovascular diseases. (elsevier.com)
  • A control group of 11 patients treated for chronic total occlusion of a coronary artery was assessed to evaluate nonspecific changes in baroreflex function during a 2-min balloon inflation in the occluded artery. (onlinejacc.org)
  • During spontaneous breathing, the application of positive end-expiratory pressure (PEEP) may affect the autonomic nervous system, as suggested by changes in baroreflex efficiency and RR variability. (inserm.fr)
  • After pretreatment with the dopamine receptor antagonist raclopride, central stimulation failed to produce any changes in baroreflex parameters. (edu.au)
  • Baroreflex activation is distinct from vagal stimulation. (wikipedia.org)
  • An aspect of the present subject matter relates to a system for providing baroreflex stimulation. (google.es)
  • The stimulator includes a pulse generator to provide a baroreflex stimulation signal adapted to provide a baroreflex therapy, and a modulator to receive the signal indicative of the adverse event and modulate the baroreflex stimulation signal based on the signal indicative of the adverse event to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy. (google.es)
  • 5 . The system of claim 1 , further comprising a waveform generator to produce baroreceptor signals of a desired morphology, wherein the modulator includes a modulator to change the morphology of the baroreflex stimulation signal based on the signal indicative of the adverse event. (google.es)
  • The baroreflex failure syndrome results from impaired afferent baroreceptive input and manifests with autonomic stimulation-induced surges in blood pressure and heart rate accompanied by distinct signs, including thunderclap headache, diaphoresis, and emotional instability. (aappublications.org)
  • It is the successor of their RHEOS baroreflex stimulation device, which we have covered several times before. (medgadget.com)
  • BRS was calculated as the slope of the baroreflex sequences between spontaneous changes in systolic blood pressure and subsequent consecutive relative risk deviation length, and was measured in the supine position and following head-up tilt for sympathetic stimulation. (ersjournals.com)
  • Twelve healthy men underwent measurement of their carotid-cardiac baroreflex response during varying conditions of vestibulo-oculomotor stimulation to test the hypothesis that vestibular and/or oculomotor stimulation associated with head movements in the yaw plane inhibit baroreflex control of heart rate. (physiology.org)
  • alpha-2 Adrenoreceptor stimulation profoundly augments baroreflex-mediated bradycardia presumably through parasympathetic activation. (mdc-berlin.de)
  • Thirty minutes after 2 h of vagal stimulation, the baroreflex was significantly depressed and plasma norepinephrine levels were significantly elevated in both groups. (islandscholar.ca)
  • The baroreflex was also significantly depressed after bilateral lidocaine injections into the insula, independent of vagal stimulation. (islandscholar.ca)
  • Closed-loop baroreflex systems utilizing sympathetic nerve trunk stimulation, spinal cord stimulation and noninvasive transcutaneous stimulation were proposed. (elsevier.com)
  • The use of baroreflex stimulation devices (also known as baroreflex activation therapy) is a potential alternative treatment for resistant hypertension and heart failure. (wellmark.com)
  • Specific devices for baroreflex stimulation have been developed, but none has been approved by the U.S. Food and Drug Administration (FDA) for any indication. (wellmark.com)
  • In subsequent studies, the role of cardiac receptor stimulation on the baroreflex control of regional resistances and sympathetic nerve activity will be studied to determine if input from these receptors (atrial and ventricular) alter the baroreflex in heart failure. (elsevier.com)
  • CONCLUSIONS Parameters describing spontaneous blood pressure and heart rate variability and indexes reflecting the baroreflex function, which were relatively normal up to a few hours before brain death, underwent marked changes with the onset of brain death. (bmj.com)
  • Interestingly, this increase in PE patients did not lead to elevated spontaneous baroreflex events, while BPV changes in both the other hypertensive groups were paralleled by alterations in baroreflex parameters. (hu-berlin.de)
  • To elucidate the neurogenic mechanisms underlying the pathophysiology of this model, we analyzed the dynamic baroreflex response to spontaneous fluctuations in arterial pressure in conscious SHRs, as well as in the Wistar-Kyoto (WKY), the Dahl salt-sensitive, the Dahl salt-resistant, and the Sprague-Dawley rat. (jci.org)
  • We then contrasted least squares linear regression slopes derived from the depressor (nitroprusside) and pressor (phenylephrine) phases with 1) slopes derived from spontaneous fluctuations of systolic arterial pressures and R-R intervals, and 2) baroreflex gain derived from cross-spectral analyses of systolic pressures and R-R intervals. (elsevier.com)
  • Although pharmacological and spontaneous vagal baroreflex responses correlate closely, pharmacological baroreflex slopes tend to be lower than those derived from spontaneous fluctuations. (elsevier.com)
  • Through pharmacological interventions (phenylephrine and sodium nitroprusside), the baroreflex control of f H was studied at ∼25°C in spring-summer- and winter-acclimated tegus. (biologists.org)
  • Sympathetic and parasympathetic baroreflex curves were determined using incremental phenylephrine and nitroprusside infusions (0.3, 0.6, 0.9, 1.2, and 1.5 microg/kg per minute). (mdc-berlin.de)
  • We evaluated a method of baroreflex testing involving sequential intravenous bolus injections of nitroprusside followed by phenylephrine and phenylephrine followed by nitroprusside in 18 healthy men and women, and we drew inferences regarding human sympathetic and vagal baroreflex mechanisms. (elsevier.com)
  • We recommend repeated sequential nitroprusside followed by phenylephrine doses as a simple, efficient-means to provoke and characterize human vagal and sympathetic baroreflex responses. (elsevier.com)
  • Under both conditions, baroreflex function curves relating AP and RSNA were constructed by fitting a sigmoid function to RSNA and AP measured during sequential nitroprusside and phenylephrine administrations. (edu.lb)
  • Baroreflex was calculated as the derivative of the variation of heart rate in function of the mean arterial pressure variation (ΔHR/ΔMAP) tested with a depressor dose of sodium nitroprusside (50 μg/kg) and with a pressor dose of phenylephrine (8μg/kg) in the right femoral venous approach through an inserted cannula. (touchcardio.com)
  • This 'neuroprosthetic baroreflex' controlled haemodynamics for extended periods of time in rodents, non-human primates and humans, after both acute and chronic SCI. (wingsforlife.com)
  • Physiology and Pathophysiology of Heart Rate and Blood Pressure Variability in Humans: Is Power Spectral Analysis Largely An Index of Baroreflex Gain? (portlandpress.com)
  • Naloxone potentiates cardiopulmonary baroreflex sympathetic control in normal humans. (ahajournals.org)
  • To evaluate the potential effect of endogenous opioids on cardiopulmonary baroreflex mechanisms in humans, we measured arterial and central venous pressures, heart rate, and efferent muscle sympathetic nerve activity (MSNA, by peroneal microneurography) during unloading of cardiopulmonary baroreceptors with incremental lower body negative pressure (LBNP, from 0 to -15 mm Hg) and during the cold pressor test in 21 normal subjects (aged 24 +/- 1 [mean +/- SEM] years). (ahajournals.org)
  • Thus, naloxone selectively potentiates cardiopulmonary baroreflex regulation of sympathetic neural activity in normal humans. (ahajournals.org)
  • However, the baroreflex control of vasomotor sympathetic nerve activity, which regulates peripheral vascular resistances, has not been examined in humans. (physiology.org)
  • Our study shows that abrupt coronary occlusion impairs baroreflex modulation of vagal and sympathetic nervous outflow in humans. (onlinejacc.org)
  • It has been known for many years that the baroreflex control of heart rate is depressed in both humans and animals with heart failure. (elsevier.com)
  • In fact, the minimization of blood pressure variability by baroreflex mechanisms is important since studies suggest that a reduced baroreflex is an independent risk factor for sudden death after myocardial infarction (2,3). (scielo.br)
  • In addition, there are numerous models that simulate a heart-rate variability that is modulated by the baroreflex (see list of prior art, Nos. (google.com)
  • Also, differences in variability among subjects are only marginally explained by differences in baroreflex function. (portlandpress.com)
  • The aim of this study was to explore blood pressure variability and closed-loop baroreflex function at rest and during mild orthostatic stress in adolescents with CFS. (harvard.edu)
  • Indices of blood pressure variability and baroreflex function (alpha-gain) were computed from monovariate and bivariate spectra in the low-frequency (LF) band (0.04 to 0.15 Hz) and the high-frequency (HF) band (0.15 to 0.50 Hz), using an autoregressive algorithm. (harvard.edu)
  • CFS in adolescents is characterized by reduced systolic blood pressure variability and a sympathetic predominance of baroreflex heart rate control during orthostatic stress. (harvard.edu)
  • Acute coronary occlusion may cause a wide range of autonomic reactions as evidenced by changes in heart rate, blood pressure and heart rate variability (10-12) , but there are limited data on potential changes of human arterial baroreflex function during acute coronary occlusion. (onlinejacc.org)
  • METHODS: We tested the effect of increasing PEEP from 5 to 10 cm H2O on the breathing variability of arterial pressure and RR intervals, and on the baroreflex. (inserm.fr)
  • RESULTS: At PEEP 10, the 12 patients with a stable pattern had lower baroreflex gain and HF-RR amplitude of variability than the 11 other patients. (inserm.fr)
  • In addition, a link seems to exist between the variability of delta and the variability in baroreflex gain between different subjects. (vt.edu)
  • The adrenergic overdrive and the baroreflex impairment may thus participate at the disease progression, favoring the development of the hypertensive state and adversely affecting the disease prognosis. (ovid.com)
  • The mechanisms of orthostatic hypotension remain unclear, but several studies demonstrated and speculated changes in neural regulation, attenuated baroreflex control of heart rate ( 10 , 15-17 , 19 ), and impairment of cerebral vascular flow autoregulation ( 38 ) in particular, as contributing factors. (physiology.org)
  • Impairment of the baroreflex can cause life-threatening arrhythmias and sudden cardiac death in patients with diabetes mellitus (DM). (biomedcentral.com)
  • Baroreflex responses to the posture changes are determined. (google.com)
  • An autonomic tone of the patient is determined based on the baroreflex responses. (google.com)
  • 2 . The method of claim 1 , wherein determining baroreflex responses to the posture changes comprises measuring the patient's heart rate during time periods corresponding to the changes in posture. (google.com)
  • 7 . The method of claim 1 , further comprising forming a baseline data set from long-term measurements of posture changes and baroreflex responses. (google.com)
  • Haemodynamic and baroreflex responses to whole-body tilting in exercising men before and after 6 weeks of bedrest. (diva-portal.org)
  • this occurrence suggests that endogenous opioids blunt baroreflex responses. (ahajournals.org)
  • Limited human studies suggest an inhibitory action of endogenous opioids on baroreflex-mediated vagal responses during arterial baroreceptor deactivation. (ahajournals.org)
  • Therefore, despite the lower f H , winter acclimation does not diminish the f H baroreflex responses or rate-pressure product, possibly because of increased stroke volume that may arise because of heart hypertrophy. (biologists.org)
  • To examine how long-lasting microgravity simulated by 6° head-down bed rest (HDBR) induces changes in the baroreflex control of muscle sympathetic nerve activity (MSNA) at rest and changes in responses of MSNA to orthostasis, six healthy male volunteers (range 26-42 yr) participated in Valsalva maneuver and head-up tilt (HUT) tests before and after 120 days of HDBR. (physiology.org)
  • Carotid baroreflex (CBR) latencies (i.e., time-to-peak responses) were examined using carotid-cardiac (peak HR responses), carotid-vasomotor (peak MAP responses), and change in MAP at the peak HR response of the corresponding stimuli ([email protected] peak ), all of which were not significant for both NP and NS. (wku.edu)
  • Interestingly, vMPFC CB1 receptors decrease cardiac baroreflex responses, while TRPV1 channels facilitate them. (deepdyve.com)
  • We compared baroreflex modulation of human vagal-cardiac and sympathetic muscle activity in healthy volunteers by measuring R-R interval and peroneal nerve responses to a profile of positive and negative (40-65 mmHg) R-wave-triggered neck pressure steps during held expiration. (unthsc.edu)
  • The hypothesis that rapid resetting of one carotid sinus baroreflex might influence responses from the other side was also tested. (mcw.edu)
  • One such approach is the electrical activation of the carotid sinus baroreflex. (wellmark.com)
  • We conclude that changes in vascular capacity are the primary mechanism responsible for changes in cardiac output during activation of the carotid sinus baroreflex. (mcw.edu)
  • The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure reflexively causes the heart rate to decrease and also causes blood pressure to decrease. (wikipedia.org)
  • Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels. (wikipedia.org)
  • 01). Thus, most of the abnormalities in overall HRV seem to be confined to the subgroup of hypertensive subjects with insulin-resistance syndrome, but baroreflex and respiratory modulation of heart rate are impaired also in hypertensive subjects without metabolic features of insulin-resistance syndrome. (nih.gov)
  • Although temperature affects heart rate ( f H ) reflex regulation in some reptiles and toads, no data are available on the influence of temperature-independent metabolic states on baroreflex. (biologists.org)
  • Hyperthermia Does Not Alter Baroreflex Control Of Heart Rate During Central Hypovolemia Associated With Simulated Hemorrhage. (wku.edu)
  • Hyperthermia reduces tolerance to central hypovolemia, however hyperthermia itself does not alter baroreflex control of heart rate or muscle sympathetic nerve activity. (wku.edu)
  • Animal research indicates that both chronic myocardial infarction and acute coronary occlusion impair baroreflex modulation of heart rate. (onlinejacc.org)
  • Animal studies suggest that arterial baroreflex control of heart rate and vascular resistance is impaired during acute myocardial ischemia (1-5) . (onlinejacc.org)
  • Differential baroreflex control of heart rate and vascular resistance in rabbits. (ahajournals.org)
  • The purpose of this study was to compare arterial baroreflex control of heart rate (HR) during a central hypovolemic stress in the elderly and young males. (nii.ac.jp)
  • Observations revealed the existence of long intermittent periods (lasting up to several minutes) of engagement and disengagement of baroreflex control of heart rate. (jci.org)
  • body mass index: 24+/-1.3 kg/m(2)), we determined baroreflex control of heart rate and sympathetic traffic after ingestion of the selective alpha-2 adrenoceptor antagonist yohimbine (20 mg) or placebo. (mdc-berlin.de)
  • Yohimbine selectively attenuates baroreflex heart rate control in normotensive young men possibly through parasympathetic mechanisms. (mdc-berlin.de)
  • In the second series of experiments, the baroreflex control of heart rate was evaluated in dogs before and after heart failure had been induced. (elsevier.com)
  • Baroreflex failure is a rare disorder that causes fluctuations in blood pressure with episodes of severe hypertension (high blood pressure) and elevated heart rate in response to stress, exercise, and pain. (cdc.gov)
  • [1] [2] Symptoms of baroreflex failure may include headache, sweating, and a heart rate that does not respond to medications. (cdc.gov)
  • In the present study, the reflex effects of low-dose (12.5-50 ng·kg -1 ·min -1 ) intracoronary epinephrine infusion on the arterial baroreflex control of heart rate were studied. (nebraska.edu)
  • Atropine abolished the effects of intracoronary epinephrine on arterial baroreflex control of heart rate. (nebraska.edu)
  • We conclude that intracoronary epinephrine reflexly attenuates the arterial baroreflex control of heart rate in the conscious dog through activation of ventricular receptors. (nebraska.edu)
  • Baroreflex function following spinal cord injury. (biomedsearch.com)
  • The purpose of this paper is to review the mechanisms underlying effective baroreflex function, describe the techniques available to measure baroreflex function, and summarize the literature examining baroreflex function after SCI. (biomedsearch.com)
  • Briefly, although cardiovagal baroreflex function is reduced markedly in those with high level lesions (above the 6th thoracic level) the reduction appears partially mitigated in those with low lesion levels. (biomedsearch.com)
  • The purpose of this study was to compare the value of differing prognostic indicators with measures of autonomic function and to assess the safety of arterial baroreflex testing early after infarction. (bmj.com)
  • The combined influence of hyperthermia and profound central hypovolemia on baroreflex function remains unknown. (wku.edu)
  • 18,19 Based on these findings, we hypothesized that arterial baroreflex function may be compromised in patients with obstructive jaundice, which may help to explain the enhanced susceptibility to those well-known perioperative complications. (asahq.org)
  • These factors are implicated in the regulation of arterial baroreflex function and/or autonomic nervous system activity. (asahq.org)
  • We sought to assess baroreflex function in patients with hypertrophic cardiomyopathy (HCM). (onlinejacc.org)
  • Conclusions- Patients with POTS have blunted vasopressor response to Ang II and impaired baroreflex function. (ahajournals.org)
  • There is a possibility that there are some impairments of baroreflex arc function including the distensibility of vascular where baroreceptors are in the old during LBNP. (nii.ac.jp)
  • Guido Grassi, " Sympathetic and Baroreflex Function in Hypertension: Implications for Current and New Drugs", Current Pharmaceutical Design (2004) 10: 3579. (eurekaselect.com)
  • These data support the existence of an inhibitory central effect of the AT2 receptor on baroreflex function. (mdc-berlin.de)
  • Changes in canine cardiac function and venous return curves by the carotid baroreflex. (mcw.edu)
  • Objective: patients with hypertension or hypertensive animals is often associated with blood pressure elevated volatility (BPV) and arterial baroreflex (ABR) function defects. (dissertationtopic.net)
  • Modulation of baroreflex and baroreceptor function in experimental heart failure. (elsevier.com)
  • Since there were no further changes in the indices of hypertrophy, the presence of the ACE inhibitor was likely to have been responsible for restoring the remaining 35% of the vagal baroreflex not affected by structural factors. (ovid.com)
  • 16,17 An intact vagal baroreflex recently has been found to be necessary for improving survival in sepsis. (asahq.org)
  • We found that vagal baroreflex slopes are less when arterial pressures are falling than when they are rising and that this hysteresis exists over pressure ranges both below and above baseline levels. (elsevier.com)
  • There is no correlation between sympathetic and vagal baroreflex gains. (elsevier.com)
  • The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. (wikipedia.org)
  • Finally, we describe the potential mechanisms responsible for baroreflex dysfunction after SCI and propose future avenues for research. (biomedsearch.com)
  • By describing clearly the existing deficiencies in the understanding of baroreflex mechanisms, it points a way for future research in this exciting and important area of medical science. (booktopia.com.au)
  • It is intended as a celebration of the advances that have been made and, by describing clearly the existing deficiencies in the understanding of baroreflex mechanisms, it points a way for future research in this exciting and important area of medical science. (booktopia.com.au)
  • The arterial baroreflexes are important mechanisms for the overall regulation of blood pressure during orthostatic stress and exercise ( 13 ). (physiology.org)
  • 25-28 Accordingly, we included these measures in the hope to find some underlying mechanisms for impaired baroreflex in jaundiced patients. (asahq.org)
  • Effect of systolic blood pressure and carotid stiffness on baroreflex gain in elderly subjects. (harvard.edu)
  • Abrupt decreases and increases in systolic arterial blood pressure produce baroreflex mediated shortening and lengthening, respectively, of the R-R interval. (vt.edu)
  • This phenomenon, otherwise known as the cardivagal baroreflex, is best described by the sigmoid relationship between R-R interval length and systolic blood pressure. (vt.edu)
  • The baroreflex control of the cardiac vagal outflow can then be assessed by the relation of the R-R interval to systolic blood pressure. (vt.edu)
  • Il riflesso del baroreceptor--a volte riferito a semplicemente come il baroreflex--le guide mantengono una pressione sanguigna costante cambiando la frequenza cardiaca o la resistenza nei vasi sanguigni. (news-medical.net)
  • CB1 cannabinoid receptors are expressed on vagal afferent fibers and neurons within the solitary tract nucleus (NTS), providing anatomical evidence for their role in arterial baroreflex modulation. (rti.org)
  • Medial prefrontal cortex TRPV1 and CB1 receptors modulate cardiac baroreflex activity by. (deepdyve.com)
  • Therefore, the hypothesis of the present study is that the vMPFC NMDA/NO pathway is regulated by both CB1 and TRPV1 receptors in the modulation of cardiac baroreflex activity. (deepdyve.com)
  • Based on these results, we conclude that vMPFC CB1 and TRPV1 receptors inhibit or facilitate the cardiac baroreflex activity by stimulating or blocking the NMDA activation and NO synthesis. (deepdyve.com)
  • When these receptors are stretched, as occurs with increases in BP, the baroreflex is activated. (wellmark.com)
  • Head motion alone reduced baseline baroreflex responsiveness by 30% from 3.8 +/- 0.5 to 2.6 +/- 0.5 ms/mmHg. (physiology.org)
  • Eye motion alone also reduced the baroreflex response by 13% (0.5 ms/mmHg) to 3.3 +/- 0.5 ms/mmHg. (physiology.org)
  • We assessed the carotid-cardiac baroreflex response by plotting R-R intervals (in milliseconds) at each of eight neck pressure steps with their respective carotid distending pressures (in millimeters mercury). (physiology.org)
  • Resstel, Leonardo 2018-05-29 00:00:00 The ventral medial prefrontal cortex (vMPFC) facilitates the cardiac baroreflex response through N-methyl-d-aspartate (NMDA) receptor activation and nitric oxide (NO) formation by neuronal NO synthase (nNOS) and soluble guanylate cyclase (sGC) triggering. (deepdyve.com)
  • Vagal, but not sympathetic baroreflex gains vary inversely with subjects' ages and their baseline arterial pressures. (elsevier.com)
  • The purpose of the present review is to discuss data relating sympathetic activity to the baroreflex control of arterial pressure in two different experimental models: neurogenic hypertension by sinoaortic denervation (SAD) and high-renin hypertension by total aortic ligation between the renal arteries in the rat. (scielo.br)
  • SAD depresses baroreflex regulation of renal sympathetic activity in both the acute and chronic phases. (scielo.br)
  • The baroreflex can begin to act in less than the duration of a cardiac cycle (fractions of a second) and thus baroreflex adjustments are key factors in dealing with postural hypotension, the tendency for blood pressure to decrease on standing due to gravity. (wikipedia.org)
  • Baroreflex induced changes in blood pressure are mediated by both branches of the autonomic nervous system: the parasympathetic and sympathetic nerves. (wikipedia.org)
  • At normal resting blood pressures, many baroreceptors are actively reporting blood pressure information and the baroreflex is actively modulating autonomic activity. (wikipedia.org)
  • Baroreflex activation therapy is an approach to treating resistant high blood pressure that uses an implanted device to electrically stimulate baroreceptors in the carotid sinus region. (wikipedia.org)
  • The major role of the arterial baroreflex is to maintain blood pressure (BP) homeostasis. (scielo.br)
  • The primary purpose of the arterial baroreflex is to provide rapid and efficient stabilization of arterial blood pressure on a beat-to-beat basis by means of carotid and aortic baroreceptors. (scielo.br)
  • Baroreflex regulation of blood pressure is important for maintaining appropriate tissue perfusion. (biologists.org)
  • In winter lizards, resting and minimum f H were lower than in spring-summer animals (respectively, 13.3±0.82 versus 10.3±0.81 and 11.2±0.65 versus 7.97±0.88 beats min −1 ), while no acclimation differences occurred in resting blood pressure (5.14±0.38 versus 5.06±0.56 kPa), baroreflex gain (94.3±10.7 versus 138.7±30.3% kPa −1 ) or rate-pressure product (an index of myocardial activity). (biologists.org)
  • A special evaluation procedure of the BRS test also permits conclusions about the latent period (see list of prior art, No. [6]), that is, the period between a drop in blood pressure and the response of the sino-atrial node due to the baroreflex but the procedure is far from conventional. (google.com)
  • Under orthostasis, the baroreflex mediates tachycardia and peripheral vasoconstriction to lessen gravity-induced fluid shift and to preserve arterial blood pressure. (physiology.org)
  • Peripheral vascular resistance is under baroreflex control via vasomotor sympathetic nerve activity, which plays a most important role in the maintenance of arterial blood pressure during orthostasis ( 13 , 21 , 27 ). (physiology.org)
  • Arterial baroreflex is a powerful regulator of blood pressure and sympathetic nervous system. (elsevier.com)
  • The bionic baroreflex system basically consists of an artificial pressure sensor, a neurostimulator for autonomic nerves and a regulator that encodes blood pressure into neurostimulation. (elsevier.com)
  • In this article, we introduce the closed-loop neuromodulation technology for baroreflex blood pressure control and discuss future direction of development of this technology. (elsevier.com)
  • However, baroreflex failure can result from surgery or radiation treatment for cancers of the neck, injury to the nerves involved in sensing blood pressure, or a degenerative neurologic disease. (cdc.gov)
  • Lidocaine block of the pericoronary nerves, which blocked the ventricular afferent pathway, eliminated the effects of intracoronary epinephrine on the arterial baroreflex. (nebraska.edu)
  • One device, called the Barostim neo™ (CVRx™, previously called the Rheos® Baroreflex Hypertension Therapy System) is approved for sale in Europe for hypertension and heart failure patients. (wellmark.com)
  • Mean and variance of RRi and SBP, and baroreflex evaluated by phase, gain (α), and coherence (K 2 ) were determined. (scielo.br)
  • During LBNP, compared to controls, alpha-gain HF decreased more, and alpha-gain LF and the ratio of alpha-gain LF/alpha-gain HF increased more in CFS patients, all suggesting greater shift from parasympathetic to sympathetic baroreflex control. (harvard.edu)
  • Increasing PEEP was generally associated with a decreased baroreflex gain and a greater stability of HF-RR amplitude and cardiorespiratory phase difference. (inserm.fr)
  • The linear portion of this relationship is used to derive the slope or gain of the cardiovagal baroreflex. (vt.edu)
  • Thus, analysis of baroreflex gain when nonlinearities are not revealed is problematic. (vt.edu)
  • A new method of gain estimation was developed that combines the strengths of the current methods of gain estimation with the knowledge of the classifications of baroreflex trials. (vt.edu)
  • Using this method, cardiovagal baroreflex gain assessment can be maximized if threshold-heavy, saturation-heavy, and random trials are filtered out of the analysis and the manual method is used to estimate gain on the remaining trials. (vt.edu)
  • We calculated sympathetic baroreflex gain from integrated muscle sympathetic nerve activity and diastolic pressures. (elsevier.com)
  • and iv) low tachycardic baroreflex, baroreflex gain between -1 and -3 tested with sodium nitroprusside. (touchcardio.com)
  • Baroreflex dysfunction observed in diabetic subjects has important clinical implications, because the arterial baroreceptors constitute an important system that acts against wide oscillations in arterial pressure (AP), acting on both the sympathetic and parasympathetic limbs of the autonomic nervous system. (hindawi.com)
  • BACKGROUND: Baroreflex allows to reduce sudden rises or falls of arterial pressure through parallel RR interval fluctuations induced by autonomic nervous system. (inserm.fr)
  • The aim of this study was to compare baroreflex among frail, prefrail, and nonfrail individuals, in supine and orthostatic positions. (scielo.br)
  • Therefore, dysfunction of baroreflex control of vasomotor sympathetic nerve activity can contribute both to orthostatic intolerance and decreased upright exercise performance after exposure to real and simulated microgravity ( 13 , 21 , 27 ). (physiology.org)
  • However, it is unknown whether the limited involvement of the baroreflex control during an orthostatic stimulus has some impact on the quality of life of the FMS patient. (phoenixrising.me)
  • Additionally, clinical trials have shown an association between baroreflex dysfunction and morbidity and mortality [ 3 - 5 ]. (hindawi.com)
  • In this paper, we discuss the main contributions from our laboratory and others regarding cardiac-autonomic imbalance and baroreflex dysfunction. (hindawi.com)
  • Baroreflex dysfunction has been observed in women with FMS. (phoenixrising.me)
  • We have previously demonstrated a specific abnormality in the afferent limb of the cardiopulmonary baroreflex in patients with vasovagal syncope. (onlinejacc.org)
  • we therefore hypothesize a similar abnormality in the afferent limb of the cardiopulmonary baroreflex arc. (onlinejacc.org)
  • I have afferent baroreflex distinction from head and neck I radiation for cancer 18 years ago. (patient.info)
  • Integrated and carotid artery baroreflex sensitivities were similar in patients and control subjects (14 ± 7 vs. 14 ± 6 ms/mm Hg, p = NS and −3 ± 2 vs. −4 ± 2 ms/mm Hg, p = NS, respectively). (onlinejacc.org)
  • These results suggest that an increase in IMT occurs in concurrence with a reduction of compliance and the baroreflex control of HR during baseline and hypovolemic stress in the elderly. (nii.ac.jp)

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