Baroreflex: 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.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Pressoreceptors: Receptors in the vascular system, particularly the aorta and carotid sinus, which are sensitive to stretch of the vessel walls.Sympathetic Nervous System: 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.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Phenylephrine: An alpha-1 adrenergic agonist used as a mydriatic, nasal decongestant, and cardiotonic agent.Carotid Sinus: 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.Vagus Nerve: 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).Autonomic Nervous System: 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.Reflex: 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.Nitroprusside: 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.Solitary Nucleus: 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.Bradycardia: 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.Valsalva Maneuver: Forced expiratory effort against a closed GLOTTIS.Denervation: The resection or removal of the nerve to an organ or part. (Dorland, 28th ed)Cardiovascular System: The HEART and the BLOOD VESSELS by which BLOOD is pumped and circulated through the body.Consciousness: Sense of awareness of self and of the environment.Supine Position: The posture of an individual lying face up.Trimethaphan: A nicotinic antagonist that has been used as a ganglionic blocker in hypertension, as an adjunct to anesthesia, and to induce hypotension during surgery.Arteries: The vessels carrying blood away from the heart.Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Reflex, Abnormal: 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.Cardiovascular Physiological Phenomena: Processes and properties of the CARDIOVASCULAR SYSTEM as a whole or of any of its parts.Heart: The hollow, muscular organ that maintains the circulation of the blood.Lower Body Negative Pressure: 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.Tilt-Table Test: 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)Parasympathetic Nervous System: 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.Hypotension, Orthostatic: 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.Vasomotor System: The neural systems which act on VASCULAR SMOOTH MUSCLE to control blood vessel diameter. The major neural control is through the sympathetic nervous system.Ganglionic Blockers: 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.Carotid Arteries: 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.Head-Down Tilt: Posture while lying with the head lower than the rest of the body. Extended time in this position is associated with temporary physiologic disturbances.Tachycardia: 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.Peroneal Nerve: 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.Posture: The position or attitude of the body.Dizziness: An imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness.Hypertension: 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.Autonomic Nervous System Diseases: 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.Central Venous Pressure: The blood pressure in the central large VEINS of the body. It is distinguished from peripheral venous pressure which occurs in an extremity.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Autonomic Denervation: The removal or interruption of some part of the autonomic nervous system for therapeutic or research purposes.Vagus Nerve Diseases: 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.Electrocardiography: 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.Medulla Oblongata: 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.Sympathomimetics: 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.Rats, Sprague-Dawley: 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.Models, Cardiovascular: 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.Photoplethysmography: 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.Vasodilator Agents: Drugs used to cause dilation of the blood vessels.Cardiovascular Deconditioning: A change in cardiovascular function resulting in a reduction in BLOOD VOLUME, and reflex DIURESIS. It occurs frequently after actual or simulated WEIGHTLESSNESS.Gravity Suits: 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.Pulse: 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.Antihypertensive Agents: Drugs used in the treatment of acute or chronic vascular HYPERTENSION regardless of pharmacological mechanism. Among the antihypertensive agents are DIURETICS; (especially DIURETICS, THIAZIDE); ADRENERGIC BETA-ANTAGONISTS; ADRENERGIC ALPHA-ANTAGONISTS; ANGIOTENSIN-CONVERTING ENZYME INHIBITORS; CALCIUM CHANNEL BLOCKERS; GANGLIONIC BLOCKERS; and VASODILATOR AGENTS.Microinjections: The injection of very small amounts of fluid, often with the aid of a microscope and microsyringes.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Fourth Ventricle: 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.Sympathetic Fibers, Postganglionic: 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.Chemoreceptor Cells: 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.Angiotensin II: 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.Vascular Resistance: 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.Exercise: 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.Infusions, Intraventricular: The delivery of a drug into a fluid-filled cavity of the brain.Arterial Pressure: 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.Pure Autonomic Failure: 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.Rats, Inbred SHR: A strain of Rattus norvegicus with elevated blood pressure used as a model for studying hypertension and stroke.Atropine Derivatives: Analogs and derivatives of atropine.Norepinephrine: 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.Respiration: 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, Intraventricular: Injections into the cerebral ventricles.Syncope, Vasovagal: Loss of consciousness due to a reduction in blood pressure that is associated with an increase in vagal tone and peripheral vasodilation.Muscle, Skeletal: 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.Sinus of Valsalva: The dilatation of the aortic wall behind each of the cusps of the aortic valve.Dogs: 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)Hypotension: 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.Neck: The part of a human or animal body connecting the HEAD to the rest of the body.Respiratory Mechanics: 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.Nitroglycerin: A volatile vasodilator which relieves ANGINA PECTORIS by stimulating GUANYLATE CYCLASE and lowering cytosolic calcium. It is also sometimes used for TOCOLYSIS and explosives.Vagotomy: The interruption or removal of any part of the vagus (10th cranial) nerve. Vagotomy may be performed for research or for therapeutic purposes.Telemetry: 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)Adrenergic Fibers: Nerve fibers liberating catecholamines at a synapse after an impulse.Suction: 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.Losartan: An antagonist of ANGIOTENSIN TYPE 1 RECEPTOR with antihypertensive activity due to the reduced pressor effect of ANGIOTENSIN II.Signal Processing, Computer-Assisted: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.Sinoatrial Node: 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)

*Baroreflex

The baroreflex can begin to act in less than the duration of a cardiac cycle (fractions of a second) and thus baroreflex ... The baroreflex may be responsible for a part of the low-frequency component of heart rate variability, the so-called Mayer ... Baroreflex activation therapy devices have received CE Mark for European sale, but have not received FDA approval for sale in ... The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure reflexively causes the heart rate to ...

*Heart rate turbulence

HRT is widely considered[by whom?] to be a baroreflex phenomenon. That is, a PVC interrupts the normal cardiac cycle, so the ... and activate the baroreflex in reverse. This time, the brain reinstates parasympathetic nerve signals and decreases sympathetic ...

*Carotid sinus

Carotid body Baroreflex S., Pellerito, John; F., Polak, Joseph (2012). Introduction to vascular ultrasonography. Saunders/ ...

*Rostral ventrolateral medulla

The RVLM is notably involved in the baroreflex. It receives inhibitory GABAergic input from the caudal ventrolateral medulla ( ...

*Calponin 1

Masuki S, Takeoka M, Taniguchi S, Nose H (March 2003). "Enhanced baroreflex sensitivity in free-moving calponin knockout mice ...

*Cushing reflex

It is widely accepted that the Cushing reflex acts as a baroreflex, or homeostatic mechanism for the maintenance of blood ... Schmidt EA, Czosnyka Z, Momjian S, Czosnyka M, Bech RA, Pickard JD (2005). "Intracranial baroreflex yielding an early cushing ...

*Inappropriate sinus tachycardia

"Impaired Baroreflex Gain in Patients with Inappropriate Sinus Tachycardia". Journal of Cardiovascular Electrophysiology. 16 (1 ...

*Pathophysiology of hypertension

This baroreflex resetting seems to be mediated, at least partly, by a central action of angiotensin II. Additional small- ... Guo GB, Abboud FM (May 1984). "Impaired central mediation of the arterial baroreflex in chronic renal hypertension". The ... Guo GB, Thames MD, Abboud FM (August 1983). "Arterial baroreflexes in renal hypertensive rabbits. Selectivity and redundancy of ... Furthermore, there is central resetting of the aortic baroreflex in hypertensive patients, resulting in suppression of ...

*Neurocardiology

The body continually attempts to maintain homeostasis through the baroreflex. This balance in the autonomic neural input to the ...

*Julia Newton

"Reduced heart rate variability and baroreflex sensitivity in primary biliary cirrhosis. Hollingsworth, K.G.; Newton, J.L.; ...

*Richard Peto

Gribbin, B; Pickering, TG; Sleight, P; Peto, R (Oct 1971). "Effect of age and high blood pressure on baroreflex sensitivity in ...

*Effects of alcohol on memory

Sun MK, Reis DJ (1992). Effects of systemic ethanol on medullary vasomotor neurons and baroreflexes. Neuroscience Letters, 137( ...

*KCNMB1

"The BK channel beta1 subunit gene is associated with human baroreflex and blood pressure regulation". Journal of Hypertension. ...

*Central venous pressure

The cardiopulmonary baroreflex responds to an increase in CVP by decreasing systemic vascular resistance while increasing heart ... "Stimulation of the Cardiopulmonary Baroreflex Enhances Ventricular Contractility in Awake Dogs: A Mathematical Analysis Study ...

*Nicoladoni sign

June 2004). "Acute arterio-venous fistula occlusion decreases sympathetic activity and improves baroreflex control in kidney ...

*Endoscopic thoracic sympathectomy

The baroreflex response for maintaining cardiovascular stability is suppressed in the patients who received the ETS. Exertional ... Kawamata YT, Homma E, Kawamata T, Omote K, Namiki A (2001). "Influence of Endoscopic Thoracic Sympathectomy on Baroreflex ... baroreflex,lung volume, pupil dilation, skin temperature and other aspects of the autonomic nervous system, like the essential ... veins Sympathetic denervation is one of the causes of Mönckeberg's sclerosis T2-3 sympathectomy suppressed baroreflex control ...

*Negative feedback

Some biological systems exhibit negative feedback such as the baroreflex in blood pressure regulation and erythropoiesis. Many ...

*Orthostatic hypertension

Baroreflex and autonomic pathways normally ensure that blood pressure is maintained despite various stimuli including postural ... largely may be due to an activation of the renin system caused by nephroptosis and partly due to a reduced baroreflex ...

*Zusanli

2006). "Short-term electroacupuncture at Zusanli resets the arterial baroreflex neural arc toward lower sympathetic nerve ...

*Hookah

It also impairs baroreflex control (which helps to control blood pressure) and cardiac autonomic functioning (which has many ... Al-Kubati, M; Al-Kubati, AS; al'Absi, M; Fiser, B. (2006). "The short-term effect of water-pipe smoking on the baroreflex ...

*Heart rate variability

Factors that affect the input are the baroreflex, thermoregulation, hormones, sleep-wake cycle, meals, physical activity, and ...

*Microneurography

The findings support earlier observations that weightlessness results in a decrease of MSNA activity through a baroreflex ... Instantaneous sympathetic activity in muscle nerves (MSA / MSNA) is heavily controlled by baroreflex mechanisms, resulting in a ...

*Choke-out

Due to the baroreflex, this causes vasodilation, or widening of the brain's blood vessels intended to relieve high pressure. ... baroreflex causing vasodilation). Since blood pressure has not actually increased as the brain thinks it has, the dilation ...

*Cold pressor test

The hot water immersion test (HIT) is equally capable of triggering a pain response without the confounding of baroreflex ...

*Home hemodialysis

Chan CT, Jain V, Picton P, Pierratos A, Floras JS (2005). "Nocturnal hemodialysis increases arterial baroreflex sensitivity and ...
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 ...
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 ...
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 ...
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
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 ...
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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 ...
Cardiovagal innervation is evaluated by testing heart rate variability. for more information visit www.ldteck.com or call us 305 915 1399
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. ...
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 ...
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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We investigated the hemodynamic effect of synthetic atrial natriuretic factor Auriculin A (ANF) and its influence on arterial baroreflex control of heart rate, systemic blood pressure, and perfusion pressure in the hind limb (perfused at constant flow) in rabbits anesthetized with alpha-chloralose and urethane. The neural mechanisms underlying these effects were also studied. In the intact animal, a 45-minute constant infusion of ANF (2 micrograms/kg prime, 0.2 microgram/kg/min) significantly reduced mean blood pressure and increased mean perfusion pressure, while heart rate did not change. Comparable data were obtained with lower (0.5 microgram/kg + 0.05 microgram/kg/min; 1 microgram/kg + 0.1 microgram/kg/min) or higher (4 micrograms/kg + 0.4 microgram/kg/min; 8 micrograms/kg + 0.8 microgram/kg/min) doses of ANF. In addition, ANF enhanced bradycardic reflex responses to phenylephrine i.v. bolus administration, while it did not change baroreflex-mediated responses to nitroglycerin i.v. bolus ...
TY - JOUR. T1 - Chronic exercise reduces sympathetic nerve activity in rabbits with pacing-induced heart failure. T2 - A role for angiotensin II. AU - Liu, Jun Li. AU - Irvine, Scott. AU - Reid, Ian A.. AU - Patel, Kaushik P. AU - Zucker, Irving H. PY - 2000/10/10. Y1 - 2000/10/10. N2 - Background - Chronic exercise (EX) improves the quality of life and increases the survival of patients with chronic heart failure (CHF). Because sympathetic nerve activity is elevated in the CHF state, it is possible that EX is beneficial in this disease due to a decrease in sympathetic outflow. Methods and Results - We evaluated arterial baroreflex function and resting renal sympathetic nerve activity (RSNA) in EX normal and CHF rabbits before and after angiotensin II type 1 (AT1) receptor blockade. Four groups of rabbits were studied: a normal non-EX group, a normal EX group, a CHF non-EX group, and a CHF EX group. EX lowered resting RSNA in rabbits with CHF but not in normal rabbits. In addition, EX increased ...
Title:The Future of Interventional Management of Hypertension: Threats and Opportunities. VOLUME: 12 ISSUE: 1. Author(s):Alexandros Briasoulis and George Bakris. Affiliation:5841 S. Maryland Ave MC 1027, Chicago, IL 60637, USA.. Keywords:Resistant hypertension, baroreflex activation therapy, renal sympathetic denervation.. Abstract:In about 48% hypertensive patients in the United States, blood pressure remains higher than accepted treatment targets despite broad availability of effective pharmaceutical agents. Of these 48%, recent estimates define about 10-11% have treatment-resistant hypertension (TR-HTN). Compensatory changes in sympathetic nervous system function are an important component of HTN. Recent technical advances targeting the sympathetic activity of the carotid sinuses (Baroreflex Activation Therapy-BAT) and the renal sympathetic nerves (Renal Denervation Therapy-RDT) have renewed interest in invasive therapy for the treatment of drug-resistant hypertension. Encouraging results ...
In hypertension baroreceptor-mediated modulation of heart rate is impaired, resulting in a decreased vagal control. Reactive oxygen species produced locally in the vasculature decrease baroreceptor sensitivity. Folic acid has antioxidant properties. Therefore, the aim of this study was to test whether folic acid improves baroreceptor function in hypertension. Twenty-one male patients with hypertension not taking any drugs for 2 weeks participated in the study and were randomized to folic acid 5 mg or matching placebo. Cardiac and vascular sympathetic baroreceptor functions were tested before and after a single dose of folic acid or placebo with two different methods: the alpha-coefficient method and the phenylephrine (PE) and sodium nitroprusside (SNP) bolus method. In the folic acid group both methods showed significantly improved cardiac and vascular sympathetic baroreceptor sensitivity compared with placebo. This study provides evidence that folic acid improves cardiac and vascular ...
Diabetes mellitus (DM) is a disease of increasing incidence and prevalence. Arterial baroreceptors are stretch-sensitive receptors, which in a reflex manner are involved in the homeostatic control of arterial blood pressure. Diabetic subjects have depressed baroreflex sensitivity (BRS), although the exact pathomechanisms are unclear. In this review, we discuss the features, clinicaland prognostic implications of reduced BRS for diabetic patients and the potential involvement of cardiovascular autonomic neuropathy and atherosclerosis. Finally, we demonstrate evidence on interventions (e.g. pioglitazone, alpha-lipoic acid, leptin, fluvastatin, physicaltraining etc.) which could improve BRS and ameliorate cardiovascular autonomic dysfunction in diabetic patients ...
PJ Counihan, GA Haywood, AC ODonoghue, WJ McKenna; Abnormal Baroreceptor Sensitivity in Hypertrophic Cardiomyopathy. Clin Sci (Lond) 1 October 1990; 79 (s23): 13P. doi: https://doi.org/10.1042/cs079013Pb. Download citation file:. ...
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... Review of the functional areas of the brain part 1 by professor fink Central chemoreceptors respiratory system physiology nclex rn khan academy Midbrain, simplified sections of internal structure Baroreflex regulation of blood pressure, animation.
When to take creatine? How much creatine to take? What do you take it with? Ill answer these questions and more, in my beginners guide to creatine.
The Systems neurobiology Laboratory is a group of laboratories that all study various aspects of neurobiology. These laboratories include: (1) computational neurobiology Laboratory: The goal of their research is to build bridges between brain levels from the biophysical properties of synapses to the function of neural systems. (2) computational Principles of Natural Sensory Processing: Research in this lab focuses on the computational principles of how the brain processes information. (3) Laboratory for Cognitive neuroscience: This laboratory studies the neural and genetic underpinnings of language and cognition. (4) Sloan-Swartz Center for Theoretical neurobiology: The goal of this laboratory is develop a theoretical infrastructure for modern experimental neurobiology. (5) Organization and development of visual cortex: This laboratory is studying the organization and function of neural circuits in the visual cortex to understand how specific neural components enable visual perception ...and to ...
TY - JOUR. T1 - MRA of abdominal vessels. T2 - Technical advances. AU - Michaely, Henrik J.. AU - Dietrich, Olaf. AU - Nael, Kambiz. AU - Weckbach, Sabine. AU - Reiser, Maximilian F.. AU - Schoenberg, Stefan O.. PY - 2006/8. Y1 - 2006/8. N2 - Magnetic resonance angiography (MRA) in general and MRA of the abdominal vessels in particular have undergone substantial improvements in the past 5 years triggered by the introduction and application of parallel imaging (PI), new sequence techniques such as centric k-space trajectories and undersampling, dedicated contrast agents and clinical high-field scanners. All of these techniques have the potential to improve image quality and resolution or decrease the image acquisition time. However, each of them has its own specific advantages and drawbacks. This review describes the main technical innovations and focuses on the impact these developments may have on abdominal MRA. Special consideration is given to the interaction of these various technical ...
We present the results of an experimental and theoretical study of the gain (or absorption) experienced by a weak probe beam propagating through a sodium vapor in the presence of an intense pump field that is nearly resonant with the 3s → 3p atomic transition. The probe-transmission spectrum includes three distinct features that result from the modification of the atomic-level structure by the ac-Stark effect. Two of these features can lead to amplification of the probe wave. We measured the dependence of the probe spectrum on the detuning of the pump beam from resonance and on the pressure of a helium buffer gas. The experimentally obtained spectra are in good agreement with the predictions of a theoretical model based on the solution of the density-matrix equations of motion for a two-level atom and including the effects of Doppler broadening. The maximum gain measured in these experiments occurs at one of the Rabi sidebands and leads to a 38-fold increase in the intensity of the probe wave. ...
We canvas issues in using neural imaging via EEG (electroencephalography) to map human responses to spaces. We describe the technology, some experiments by others relevant to architecture, and two of our own studies. One involves testing EEG as a supplement to user preference studies of urban typologies. The second involves recording the movement and affective (emotional) states of a pedestrian while moving through open spaces in Edinburgh. We produce map overlays of several such walkers as a method of mapping responses to urban spaces.. Click here for the full report. ...
Carotid sinus reflex interactions were studied in 10 dogs anesthetized with pentobarbital sodium. The right and left carotid sinus regions were isolated and perfused at controlled pressures. Pressure in the right and left carotid sinuses were independently varied, and the resulting steady-state reflex changes in arterial pressure, heart rate, respiratory frequency, tidal volume, and total ventilation were measured. Reflex changes when carotid sinus pressure was changed on one side were strongly influenced by pressure in the contralateral carotid sinus (P less than 0.05). Right carotid sinus gain was found to be 0.628 +/- 0.058 at a left carotid sinus pressure of 50 mmHg and 0.148 +/- 0.027 when left carotid sinus pressure was 200 mmHg. Similar results were found for left carotid sinus gain. Suppression was also found for heart rate, respiratory rate, tidal volume, and total ventilation. The hypothesis that rapid resetting of one carotid sinus baroreflex might influence responses from the other ...
Sickle cell disease (SCD) is a genetic disorder that is characterized by recurrent episodes of vaso-occlusive crisis (VOC) from the sickling behavior of red blood cells. Currently, no technique can distinguish the cause or predict the occurrence of a crisis accurately and reliably. One area which has rarely been studied in SCD patients is their autonomic nervous system (ANS). Since the ANS is responsible for the moment-to-moment control of the vascular tone, we hypothesized that the ANS plays an important role in the initiation of their VOC. Computational techniques, including spectral analysis of HRV and a model which characterizes the dynamics of baroreflex and respiratory-cardiac coupling, were used to assess cardiovascular autonomic control in SCD patients and normal control (CTL) subjects. These analysis techniques were applied to responses elicited from the subjects during the application of non-invasive and easily reproducible physiological interventions, such as transient-controlled ...
Sickle cell disease (SCD) is a genetic disorder that is characterized by recurrent episodes of vaso-occlusive crisis (VOC) from the sickling behavior of red blood cells. Currently, no technique can distinguish the cause or predict the occurrence of a crisis accurately and reliably. One area which has rarely been studied in SCD patients is their autonomic nervous system (ANS). Since the ANS is responsible for the moment-to-moment control of the vascular tone, we hypothesized that the ANS plays an important role in the initiation of their VOC. Computational techniques, including spectral analysis of HRV and a model which characterizes the dynamics of baroreflex and respiratory-cardiac coupling, were used to assess cardiovascular autonomic control in SCD patients and normal control (CTL) subjects. These analysis techniques were applied to responses elicited from the subjects during the application of non-invasive and easily reproducible physiological interventions, such as transient-controlled ...
In recent years, time-varying inhomogeneous point process models have been introduced for assessment of instantaneous heartbeat dynamics as well as specific cardiovascular control mechanisms and hemodynamics. Assessment of the models statistics is established through the Wiener-Volterra theory and a multivariate autoregressive (AR) structure. A variety of instantaneous cardiovascular metrics, such as heart rate (HR), heart rate variability (HRV), respiratory sinus arrhythmia (RSA), and baroreceptor-cardiac reflex (baroreflex) sensitivity (BRS), are derived within a parametric framework and instantaneously updated with adaptive and local maximum likelihood estimation algorithms. Inclusion of second-order non-linearities, with subsequent bispectral quantification in the frequency domain, further allows for definition of instantaneous metrics of non-linearity. We here present a comprehensive review of the devised methods as applied to experimental recordings from healthy subjects during propofol ...
Andrade, C., & Zamunér, A. (2015). Effects of a hydrotherapy program on baroreflex sensitivity in women with fibromyalgia syndrome. Autonomic Neuroscience: Basic & Clinical, 192, 86. Retrieved from http://www.autonomicneuroscience.com/article/S1566-0702(15)00167-8/abstract. Ángel García, D., Martínez Nicolás, I., & Saturno Hernández, P. J. (2016). Clinical Approach to Fibromyalgia: Synthesis of Evidence-based Recommendations, a Systematic Review. Reumatología Clínica (English Edition), In press. doi:10.1016/j.reumae.2015.06.002. Retrieved from http://www.reumatologiaclinica.org/en/clinical-approach-fibromyalgia-syn.... Bağdatlı, A. O., Donmez, A., Eröksüz, R., Bahadır, G., Turan, M., & Erdoğan, N. (2015). Does addition of "mud-pack and hot pool treatment" to patient education make a difference in fibromyalgia patients? A randomized controlled single blind study. International Journal of Biometeorology, 59, 12: 1905-11. doi:10.1007/s00484-015-0997-7. Retrieved from ...
The dose of Ang II used in this study produced a mild, but immediate response in the systemic vasculature, renal vasculature, and adrenal gland. The use of Ang II infusion at a physiological dose systemically provides a powerful and reproducible method of directly assessing the vascular response in vivo.21 In the present study, we demonstrated for the first time to our knowledge an attenuated systemic vascular response to Ang II infusion in POTS. This was evidenced by the significant smaller increment in mean arterial pressure in patients with POTS compared to healthy controls. The impaired vascular response in POTS may be related to the elevated level of circulating plasma Ang II that we and others have previously described in this population.10,11 The prolonged presence of high levels of Ang II have been shown to induce a state of relative vascular resistance to the pressor effect of Ang II22 in conditions such as Bartter syndrome, cirrhosis, and pregnancy.23-25 Furthermore, low sodium intake, ...
References. 1. Rockwood K, Song X, Mitnitski A. Changes in relative fitness and frailty across the adult lifespan: evidence from the canadian national population health survey. CMAJ 2011; 183: 487-494, doi: 10.1503/cmaj.101271. [ Links ] 2. Fried LP, Tangen CM, Walston J, Newman AB, Hirsch C, Gottdiener J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci 2001; 56: M146-M156, doi: 10.1093/gerona/56.3.M146. [ Links ] 3. Flint K. Which came first, the frailty or the heart disease? Exploring the vicious cycle. J Am Coll Cardiol 2015; 65: 984-986, doi: 10.1016/j.jacc.2014.12.042. [ Links ] 4. Sergi G, Veronese N, Fontana L, De Rui M, Bolzetta F, Zambon S, et al. Pre-frailty and risk of cardiovascular disease in elderly men and women: The Pro.V.A. Study. J Am Coll Cardiol 2015; 65: 976-983, doi: 10.1016/j.jacc.2014.12.040. [ Links ] 5. Merz CNB, Elboudwarej O, Mehta P. The autonomic nervous system and cardiovascular health and disease: a complex balancing act. ...
We review the existence of vestibulosympathetic reflexes in humans. While several methods to activate the human vestibular apparatus have been used, galvanic vestibular stimulation (GVS) is a means of selectively modulating vestibular afferent activity via electrodes over the mastoid processes, causing robust vestibular illusions of side-to-side movement. Sinusoidal GVS (sGVS) causes partial entrainment of sympathetic outflow to muscle and skin. Modulation of muscle sympathetic nerve activity (MSNA) from vestibular inputs competes with baroreceptor inputs, with stronger temporal coupling to the vestibular stimulus being observed at frequencies remote from the cardiac frequency;
A cautionary tale for cardiovascular researchers unfolds as Associate Editor Nancy Kanagy talks with authors Debra Diz (Wake Forest University) and Amy Arnold (Vanderbilt University), as well as leading expert Karie Scrogin (Loyola University Chicago), about spontaneous hydronephrosis which this study reveals is associated with decreased baroreflex sensitivity. What presents as a very common, and apparently benign, renal abnormality appears to cause a potential complication in central regulation of blood pressure.. Amy C. Arnold, Hossam A. Shaltout, Shea Gilliam-Davis, Nancy D. Kock, and Debra I. Diz. Autonomic Regulation of Heart in Spontaneous Hydronephrosis Am J Physiol Heart Circ Physiol, published ahead of print April 1, 2011; doi:10.1152/ajpheart.01263.2010. ...
Since the directive gain of an antenna is the far field in the forward direction divided by the average far field it is possible to obtain antennas with maximum gain by looking for designs that have minimum for the average far field, provided that the radiation pattern is properly normalised. Rather than looking for maximum of one function (gain) one looks for the minimum of the sum of the squares of many simultaneous functions - radiated power is the square of the electric field. In this way convergency is obtained, and true maximum gain yagis can be designed within the simulation model chosen. For a detailed description see Computer Design of Very High Gain Yagi Antennas. Here the method applied is a computer program from about 1972 by Kuo and Strait, that uses piecewise linear current functions on the elements, and that does not take end capacitances into account. Nevertheless this method can be used to construct real antennas with very good performance, and I have used it to design my ...
The Systems neurobiology Laboratory is a group of laboratories that all study various aspects of neurobiology. These laboratories include: (1) computational neurobiology Laboratory: The goal of their research is to build bridges between brain levels from the biophysical properties of synapses to the function of neural systems. (2) computational Principles of Natural Sensory Processing: Research in this lab focuses on the computational principles of how the brain processes information. (3) Laboratory for Cognitive neuroscience: This laboratory studies the neural and genetic underpinnings of language and cognition. (4) Sloan-Swartz Center for Theoretical neurobiology: The goal of this laboratory is develop a theoretical infrastructure for modern experimental neurobiology. (5) Organization and development of visual cortex: This laboratory is studying the organization and function of neural circuits in the visual cortex to understand how specific neural components enable visual perception ...and to ...
Hey guys, today I decided to finally tune my amp correctly after having it at 8 oclock on the bass knob for some time now. According to ohms law guidelines, I should be aiming for 33.16volts as a max threshold before clipping occurs, with a 2.2 impedance and 500wrms amplifier. The Gear: 1x MB Quart FX1.500 Monoblock (500wrms rated) 1x Alpine Type S-12" (500wrms rated) 1x Kenwood single din headunit The Issue: With my volume set at 31 (max 35 - no clipping occurs at this volume), playing a 50hz test tone, and the GAIN on MAX (yes my speaker cables were unplugged and all bass boosting/subsonic filter off) my multi-meter only reads 30.0volts. According to ohms law not even FULL gain produces 33.16 volts (500rms worth of power). Even with MAXIMAL gain, the reading is still well under where it should be. What is causing this? Is this just a typical case of cheap product (only cost me $130 off ebay), low output? How should I set my gains accordingly???? Note: Constant power reading of 13.9v. ...
Clinical evaluation of the overall pump function of the heart is usually based on the ventricular function curve, which relates a measure of ventricular
The gain adjustment is done at the transmitter via the gyro gain connector on the channel. This MUST be plugged into a receiver channel.. There isnt good documentation for the gain setting available, so the following information is what I have personally deduced from my own observations, which may not be completely correct.. The gain setting seems to control how much the tail is allowed to drift before the gyro will correct the position. It is basically a "fussiness" value. A low gain allows the tail to drift of about 2 or 3 degrees in either direction before the gyro will correct the position. A high gain allows a drift of less than 0.5 degrees.. There are two factors which limit the maximum gain setting:. For a heli with a tail servo, the limiting factors are the tail servo resolution and the amount of slop in the tail rotor pitch control mechanism.. If the tail servo resolution is low, then the gain setting must be fairly low to prevent wag.. For a heli with a tail motor ESC, the limiting ...
The D5 professional dynamic vocal microphone for lead and backing vocals delivers a powerful sound even on the noisiest stage. Its frequency-independent supercardioid polar pattern ensures maximum gain before feedback.
The importance of counterregulatory mechanisms triggered by arterial vasodilation for the antihypertensive response to the calcium entry blocking agent nifedipine was investigated in 13 men with mild to moderate essential hypertension. Blood pressure and systemic vascular resistance were significantly reduced 30 minutes after sublingual administration of 10 mg of nifedipine while heart rate, cardiac index and plasma norepinephrine concentrations increased (all p , 0.01). Also, changes in mean blood pressure correlated inversely with arterial baroreflex sensitivity (r = -0.74, p , 0.01), suggesting that arterial baroreflex mechanisms by means of sympathetic activation tend to limit the acute antihypertensive response. Blood pressure, but not systemic vascular resistance, decreased further (p , 0.01) after 6 weeks of therapy with nifedipine 20 mg three times daily, while average heart rate, cardiac index and plasma norepinephrine concentrations had returned toward pretreatment values.. Thus, a ...
1. Animal studies have shown that arterial baroreflexes are modulated by reflexes originating from the cardiopulmonary volume receptors, and that this modulation consists of a reduction of the inhibitory influence exerted by arterial baroreceptors on the heart and peripheral circulation. This has not been confirmed in man, however, in whom no reduction in the bradycardic response to carotid baroreceptor stimulation has been observed after the mild increase in central venous pressure (right atrial catheter) and cardiopulmonary receptor activity provided by passive leg raising.. 2. In seven normotensive subjects carotid baroreceptors were gradedly stimulated by progressively increasing carotid transmural pressure through a neck chamber device, the resulting reflex lengthening in R-R interval being measured in the two-three cardiac cycles immediately after the baroreceptor stimulus. This manoeuvre was performed in control conditions and repeated during a head-out water immersion which increased ...
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... this image shows the pathway of the baroreceptor reflex the reflex that shares in the control of normal blood pressure showing: 1. aortic baroreceptor 2. aortic body 3. carotid sinus 4. carotid baroreceptor 5. inferior ganglion of vagus nerve for th
Do you want to download finger blood pressure apk for free? 9 Apps provides a huge selection of top and free ucmobile apk app for you to download. Find free finger blood pressure apk for android and install it more faster in 9Apps. Enjoy it with your android mobile phone or other android device.
Finger Blood Pressure Checker is a simulated blood pressure app which measures your blood pressure and pulse heart rate. You can use it to prank you friends that you can scan your fingerprint to take the blood pressure and heart rate using your phone.. Our Blood Pressure and Heart Rate Monitor has realistic UI Graphics and excellent sounds. When you press your finger on the fingerprint scanner, the scanner bar will scan, the display will show the dynamic heart beat diagram. After the scanning, your blood pressure result will show as three professional data, they are SYS, DIA and Pulse.. Disclaimer ...
Cyclosporine A (CsA) use is associated with hypertension and reduced baroreceptor sensitivity (BRS), but the underlying mechanisms remain unresolved. In this study, we investigated whether CsA attenuation of BRS is 1) dependent on treatment regimen, and 2) causative of the pressor response. Furthermore, we investigated whether a reduction in plasma testosterone contributes to BRS attenuation caused by short-term CsA administration. The effects of the clinically used CsA formulation (15 mg/kg/day i.v. for 5 days) on mean arterial pressure (MAP), heart rate, BRS, and body weight were investigated in conscious rats. CsA caused reproducible pressor responses (15.1 ± 3.0 mm Hg) starting after the first dose and continuing through the 5 days of the study. BRS and baseline MAP were inversely related in the CsA group because of a progressive reduction in BRS, which started on day 2 and reached ∼50% of baseline on day 5 and a cumulative elevation in MAP. The inverse BRS and MAP responses required ...
Physiological aspects. At rest two major spectral components characterize heart rate variability: the low frequency component: (LFRR , ~0.1 Hz , in normalized units, n.u.) which quantifies the sympathetic modulation of the seno-atrial node and the high frequency component (HFRR, ~0.25 Hz) an index of the cardiac vagal modulation. The low frequency component of systolic arterial pressure variability (LFSAP) is a marker of the sympathetic vasomotor regulation.. Changes in these markers over 24 hours (Circulation 1990;81:537-547), during the up-right position (Circulation 2000;101:886-892), mental stress (J Auton Nerv Syst 1991;35:33-42), shift work (Circulation 2000;102:1912-1916), or following physical training (Cardiovasc Res 1993;27:482-488), have furnished valuable non-invasive information on the autonomic modifications attending different functional conditions in healthy subjects.. - Pathophysiological aspects. Since the beginning of the nineties and more recently, Dr Furlan used power ...
Physiological aspects. At rest two major spectral components characterize heart rate variability: the low frequency component: (LFRR , ~0.1 Hz , in normalized units, n.u.) which quantifies the sympathetic modulation of the seno-atrial node and the high frequency component (HFRR, ~0.25 Hz) an index of the cardiac vagal modulation. The low frequency component of systolic arterial pressure variability (LFSAP) is a marker of the sympathetic vasomotor regulation.. Changes in these markers over 24 hours (Circulation 1990;81:537-547), during the up-right position (Circulation 2000;101:886-892), mental stress (J Auton Nerv Syst 1991;35:33-42), shift work (Circulation 2000;102:1912-1916), or following physical training (Cardiovasc Res 1993;27:482-488), have furnished valuable non-invasive information on the autonomic modifications attending different functional conditions in healthy subjects.. - Pathophysiological aspects. Since the beginning of the nineties and more recently, Dr Furlan used power ...
Short-term complexity of heart period (HP) and systolic arterial pressure (SAP) was computed to detect age and gender influences over cardiovascular control in resting supine condition (REST) and during standing (STAND). Healthy subjects (n = 110, men = 55) were equally divided into five groups (21-30; 31-40; 41-50; 51-60; and 61-70 years of age). HP and SAP series were recorded for 15 min at REST and during STAND. A normalized complexity index (NCI) based on conditional entropy was assessed. At REST we found that both NCIHP and NCISAP decreased with age in the overall population, but only women were responsible for this trend. During STAND we observed that both NCIHP and NCISAP were unrelated to age in the overall population, even when divided by gender. When the variation of NCI in response to STAND (ΔNCI = NCI at REST-NCI during STAND) was computed individually, we found that ΔNCIHP progressively decreased with age in the overall population, and women were again responsible for this trend.
Erica A Wehrwein, Ananda Basu, Timothy B Curry, Robert A Rizza, Rita Basu, and Michael J Joyner. Do the Carotid Bodies Modulate Hypoglycemic Counterregulation and Baroreflex Control of Blood Pressure In Humans?, Arterial Chemoreception: From Molecules to Systems; ISAC 2011 conference proceedings (Editor Colin Nurse), Sept 2011. ...
T cell monitoring is increasingly performed using cryopreserved PBMC. It has been suggested that resting of PBMC after thawing, that is, culturing them overnight in test medium, produces higher antigen-induced spot counts in ELISPOT assays. To evaluate the importance of overnight resting, we systematically tested cryopreserved PBMC from 25 healthy donors. CEF peptides (comprising CMV, EBV and flu antigens) were used to stimulate CD8 cells and mumps antigen to stimulate CD4 cells. The data show that resting significantly increased antigen-elicited T cell responses only for CEF high responder PBMC. The maximal gain observed was doubling of spot counts. For CEF low responders, and for mumps responders of either low- or high reactivity levels, resting had no statistically significant effect on the observed spot counts. Therefore, resting is not a generally applicable approach to improve ELISPOT assay performance, but can be recommended only for clinical subject cohorts and antigens for which it has a proven
In molecular biology, a gene is considered to comprise both a coding sequence-the region of DNA (or RNA, in the case of some viruses) that determines the structure of a protein-and a regulatory sequence-the region of DNA that controls when and where the protein will be produced. The genetic code determines how the coding DNA sequence is converted into a protein sequence (via transcription and translation). The genetic code is essentially the same for all known life, from bacteria to humans.. Through the proteins they encode, genes govern the cells in which they reside. In multicellular organisms, much of the development of the individual, as well as the day-to-day functions of the cells, is tied to genes. The genes protein products fulfill roles ranging from mechanical support of the cell structure to the transportation and manufacture of other molecules and the regulation of other proteins activities.. Due to rare, spontaneous changes (e.g. in DNA replication) mutations in the sequence of a ...
冠動脈疾患患者の交感神経活動におよぼす喫煙の影響 Effects of cigarette smoking on sympathetic nerve activity in patients with coronary artery disease. ...
TY - JOUR. T1 - Estrogen attenuates the exercise pressor reflex in female cats. AU - Schmitt, Petra M.. AU - Kaufman, Marc P. PY - 2003/10/1. Y1 - 2003/10/1. N2 - In humans, the pressor and muscle sympathetic nerve responses to static exercise are less in women than in men. The difference has been attributed to the effect of estrogen on the exercise pressor reflex. Estrogen receptors are abundant in areas of the dorsal horn receiving input from group III and IV muscle afferents, which comprise the sensory limb of the exercise pressor reflex arc. These findings prompted us to investigate the effect of estrogen on the spinal pathway of the exercise pressor reflex arc. Previously, we found that the threshold concentration of 17β-estradiol needed to attenuate the exercise pressor reflex in male decerebrate cats was 10 μg/ml (Schmitt PM and Kaufman MP. J Appl Physiol 94: 1431-1436, 2003). The threshold concentration for female cats, however, is not known. Consequently, we applied 17β-estradiol to ...
Clinical trials on carotid receptor stimulation by an implantable device showed a significant reduction in both office systolic (22 or 34 mmHg) and diastolic (18 or 20 mmHg) blood pressure, 24-hour ambulatory blood pressure (14/9 mmHg), and heart rate (12 bpm), which was evident from study onset and was maintained at follow-up. Available data suggest a beneficial effect of carotid baroreceptor stimulation on the reversal of left ventricular hypertrophy and cardiac structure and function, with attenuated mitral A-valve velocity and reduced left atrial dimensions; also carotid baropacing does not impair the renal function of patients with resistant hypertension, even during prolonged follow-up periods (13-18).. ...
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The probability and prediction of relapses were calculated in 186 patients who finished the 2 year follow-up period. Modification of G alpha with myristate can be recapitulated in E. In the several hypogonadotropic syndromes described to date autosomal and X-linked transmission have been implicated in the inheritance of the hypogonadism. The technique of low flow antegrade selective cerebral perfusion through the right brachial artery may be used for a vast majority of aortic aneurysms and dissections requiring arch repair. Relation of the Bilateral Earlobe Crease to Endothelial Dysfunction.. One patient is awaiting repair, and 1 underwent a cavopulmonary shunt. The reproductive deficits of the middle-aged Per mutant females are comparable with those seen in aged wild-type mice. Step baroreflex response in awake patients undergoing carotid viagra without doctor prescription surgery: time- and frequency-domain analysis. Our experiment assessed whether azithromycin inhibits neutrophil accumulation ...
Articular manipulation, another part to the manipulative therapies curriculum, works on the premise that different layers of the body starting right from the deepest layer of bone to the muscles, ligaments, blood vessels and nerves, all working together to create an interdependence and unity of the bodys structure. These layers interact with the central nervous system through neural components and motor components. Specific emotions with specific personalities also have an effect on the CNS which affects all these layers. Keeping a balance in these different layers maintains joint pressure. The pressure inside a joint is important. In a healthy joint exists a negative pressure,. All the joint structures stick together to create a sucking effect inside the joint, a kind of "togertherness". When dysfunctional the negative pressure decreases (becomes more positive pressure) which destroys the cartilage, and the joint falls apart. ...
An implantable device monitors the balance between sympathetic tone and parasympathetic tone as a function of an activity level. Cardio-neurological healthy users exhibit a generally sympathetic tone in conjunction with heavy activity level and a generally parasympathetic tone in conjunction with periods of low activity level. Deviations from expected results are associated with a health problem. Measured conditions are stored and available for subsequent reporting to a remote programmer. Therapy delivered by an implantable device is determined as a function of the relationship between autonomic balance and activity level.
It has long been recognized that minor minute-to-minute fluctuations in blood pressure occur in healthy individuals, and that many factors influence these fluctuations. Perhaps the easiest to observe is the influence of posture. Assumption of upright posture from a recumbent position results in a small but measurable decrease in systolic blood pressure (SBP) due primarily to a redistribution of blood volume into the lower abdomen, buttocks and legs under the influence of gravity. In most people, this decrease in blood pressure is very slight and evanescent, as a whole host of response mechanisms are immediately engaged to maintain blood pressure. Chief among these responses is the baroreflex constellation,1 in which stretch receptors in the carotid artery in the neck, and major vessels and structures in the thorax, quickly sense decreases in arterial pressure and central thoracic volume and trigger a coordinated increase in activity of the sympathetic nervous system, decrease in activity of the ...
This is the second volume in a projected five-volume survey of numerical linear algebra and matrix algorithms. It treats the numerical solution of dense and large-scale eigenvalue problems with an emphasis on algorithms and the theoretical background required to understand them. The notes and reference sections contain pointers to other methods along with historical comments. The book is divided into two parts: dense eigenproblems and large eigenproblems. The first part gives a full treatment of the widely used QR algorithm, which is then applied to the solution of generalized eigenproblems and the computation of the singular value decomposition. The second part treats Krylov sequence methods such as the Lanczos and Arnoldi algorithms and presents a new treatment of the Jacobi-Davidson method. These volumes are not intended to be encyclopedic, but provide the reader with the theoretical and practical background to read the research literature and implement or modify new algorithms.. ...
Medical Supplies and equipment News, News articles relating to medical equipment and supplies UK. Beat-to-beat blood pressure, autonomic function, News on medical supplies and equipment.
An exponential function can be easily plotted on Microsoft Excel by first creating the data set in tabular form with values corresponding to the x and y axis and then creating a scatter plot from the...
Determine the rhythms regularity. The rhythm is said to be regular when there is a constant distance between similar waves (P-P or R-R). Generally a variation of 10% is acceptable. For example, if there are 10 small boxes in an R-R interval, an R wave could be off by 1 small box and still be considered regular. In an irregular rhythm if the variation between the shortest and longest R-R interval is less than four small boxes (0.16 sec) the rhythm is essentially regular. If the R-R intervals vary by more than 0.16 seconds the rate is irregular. A regularly irregular rhythm is where the R-R intervals are not the same and vary by more than 0.16 sec but have a repeating pattern of irregularity ...
Signed-off-by: Andrew Wong ,[email protected], --- builtin/reset.c , 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/builtin/reset.c b/builtin/reset.c index 6004803..740263d 100644 --- a/builtin/reset.c +++ b/builtin/reset.c @@ -318,7 +318,12 @@ int cmd_reset(int argc, const char **argv, const char *prefix) _(reset_type_names[reset_type])); } if (reset_type == NONE) - reset_type = MIXED; /* by default */ + { + if(is_merge()) + reset_type = MERGE; + else + reset_type = MIXED; + } if (reset_type != SOFT && reset_type != MIXED) setup_work_tree(); -- 1.9.0.6.g16e5f9a -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html ...
A sharp inhalation has the advantage of automatically contracting the core muscles, which does not happen during slow breathing. The same effect is observed
Morphine and other opiates tend to make a person nauseated and they may vomit after taking the drug. Opiates slow breathing, which is what usually kills a person who has taken too much of the drug. A person on these drugs tends to be sleepy and they may dope off.
Page 2 - No... I do not want to get into which one is better. I am in a BSN program, it was the best choice for me for a number of reasons and I am happy with that choice. I am simply curious why some
Considering the small number of studies in the literature that investigated the association between SSCS and cardiac autonomic regulation, we endeavored to review recent studies from our group and others groups regarding this issue. The analysis of manuscripts selected for this review showed that exposure to SSCS impairs the autonomic regulation of the heart through the central nervous system and through the periphery.. A first study from our group mentioned in this review failed to report changes in baroreflex function in Wistar rats exposed to SSCS during three weeks, five days per week for 180 minutes per day. The baroreflex sensitivity was compared between rats exposed to SSCS and rats exposed to fresh air [7]. Nevertheless, previous studies indicated that active smoking influences cardiovascular reflexes. It was indicated that cigarette smoking in active smokers increases sympathetic nerve activity through an effect mediated by the central nervous system and also through a direct peripheral ...
1. The carotid baroreceptors were stimulated for 2 min by neck suction at −30 and −60 mmHg in 19 normotensive subjects and 12 patients with moderate essential hypertension.. 2. Blood pressure was measured with a mercury sphygmomanometer and heart rate was derived from beat-to-beat analysis of the electrocardiogram. Blood flow was measured simultaneously at calf and finger with venous occlusion plethysmography and the vascular resistance was calculated.. 3. During neck suction at − 30 and − 60 mmHg there was a significant decrease in arterial blood pressure and heart rate. There was a transient vasodilatation of the calf blood vessels, while there was a sustained vasoconstriction of the finger blood vessels. These results were qualitatively similar in both groups; however, there were quantitative differences.. 4. These experiments show that there is a selective autonomic control of the different peripheral vascular beds by the carotid baroreceptors in both normotension and mild essential ...
Integration and coordination of somato-visceral sensory information is crucial to achieve adaptive behavioural responses. We have recently shown that sensory vagal and somato-sensory (sciatic nerve) inputs converge in neurons of the rostral ventrolateral medulla oblongata, which was implicated in adjusting visceral activities to changing somatic performances. In the present study, the neuronal mechanism of interaction between sciatic and vagal sensory inputs was examined in the rostral ventrolateral medulla oblongata using in vivo intracellular recording and labelling. Conditioning stimulation of the contralateral sciatic nerve (2 V) led to a time-dependent inhibition of responses to vagal stimulation (100 µA) in each RVLM neuron that received convergent sciatic and vagal sensory inputs (n = 50). None of these neurons had direct spinal projections, and only 8% of them exhibited a visible response to stimulation of the aortic depressor nerve. A significant attenuation of the amplitude of vagal ...
Background: Data on the value of baseline brain natriuretic peptide (BNP) and autonomic markers in predicting heart failure (HF) hospitalization after an acute myocardial infarction (AMI) are limited.. Methods: A consecutive series of patients with AMI without a previous history of HF (n = 569) were followed up for 8 years. At baseline, the patients had a blood sample for determination of BNP, a 24-hour Holter recording for evaluating heart rate variability (HRV) and heart rate turbulence (HRT), and an assessment of baroreflex sensitivity (BRS) using phenylephrine test.. Results: During the follow-up, 79 (14%) patients were hospitalized due to HF. Increased baseline BNP, decreased HRV, HRT, and BRS had a significant association with HF hospitalization in univariate comparisons (P , 0.001 for all). After adjusting with all the relevant clinical parameters, BNP, HRV, and HRT still significantly predicted HF hospitalization (P , 0.001 for BNP and for the short-term scaling exponent α1, P , 0.01 ...

Faculty Collaboration Database - Interaction of right and left carotid sinus baroreflexes in the dog.  Am J Physiol 1986 Jan...Faculty Collaboration Database - Interaction of right and left carotid sinus baroreflexes in the dog. Am J Physiol 1986 Jan...

Interaction of right and left carotid sinus baroreflexes in the dog. Am J Physiol 1986 Jan;250(1 Pt 2):H96-107 PMID: 3942243. ... The hypothesis that rapid resetting of one carotid sinus baroreflex might influence responses from the other side was also ...
more infohttps://fcd.mcw.edu/?module=search&func=showPublication&id=9189

Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive...Aortic depressor nerve stimulation does not impede the dynamic characteristics of the carotid sinus baroreflex in normotensive...

To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another ... To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another ... To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another ... To examine whether the electrical stimulation from one baroreflex system impedes normal short-term AP regulation via another ...
more infohttps://okayama.pure.elsevier.com/en/publications/aortic-depressor-nerve-stimulation-does-not-impede-the-dynamic-ch

Transcutaneous electrical acupuncture stimulation as a countermeasure against cardiovascular deconditioning during 4 days of...Transcutaneous electrical acupuncture stimulation as a countermeasure against cardiovascular deconditioning during 4 days of...

TEAS treatment ameliorated the reduction in plasma volume and thus the spontaneous arterial-cardiac baroreflex. ... 1 Previous studies have also found that spontaneous baroreflex sensitivity is reduced after bed rest and spaceflight.14 EA is ... suggests that reductions in plasma volume are largely responsible for the observed changes in autonomic arterial baroreflex ...
more infohttp://aim.bmj.com/content/33/5/381

Baroreflex - WikipediaBaroreflex - Wikipedia

The baroreflex can begin to act in less than the duration of a cardiac cycle (fractions of a second) and thus baroreflex ... The baroreflex may be responsible for a part of the low-frequency component of heart rate variability, the so-called Mayer ... Baroreflex activation therapy devices have received CE Mark for European sale, but have not received FDA approval for sale in ... The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure reflexively causes the heart rate to ...
more infohttps://en.wikipedia.org/wiki/Baroreflex

baroreflex | Hypertensionbaroreflex | Hypertension

Prolonged Baroreflex Activation Abolishes Salt-Induced Hypertension After Reductions in Kidney MassNovelty and Significance ... Abstract 268: Toll-like Receptor 9 (TLR9) Plays a Key Role in the Autonomic Cardiac and Baroreflex Control of Arterial Pressure ... Respiratory Network Enhances the Sympathoinhibitory Component of Baroreflex of Rats Submitted to Chronic Intermittent Hypoxia ... Abstract 157: MAP Kinase Phosphatase-1 Inhibitor Injection into the Solitary Tract Nucleus Impairs Cardiovagal Baroreflex ...
more infohttp://hyper.ahajournals.org/keyword/baroreflex

Baroreflex sensitivity in frailty syndromeBaroreflex sensitivity in frailty syndrome

Baroreflex was evaluated by phase, coherence (K2), and gain (α). Baroreflex was calculated by cross-spectral analysis using a ... In older adults, a decrease in baroreflex, which is evaluated by α index, is expected (10,34-36). Furthermore, some pathologies ... Nevertheless, the baroreflex allowed us to more clearly detect changes in the coupling of HP and BP control systems. The ... In the aging process, a decline in baroreflex sensitivity (BRS) is expected (9,10). Therefore, there is a reduction of HR ...
more infohttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2019000400602&lng=en&nrm=iso&tlng=en

Baroreflex function following spinal cord injury.Baroreflex function following spinal cord injury.

... describe the techniques available to measure baroreflex function, and summarize the literature examining baroreflex function ... Baroreflex sensitivity (i.e., the capability of the autonomic nervous system to detect and respond efficaciously to acute ... Briefly, although cardiovagal baroreflex function is reduced markedly in those with high level lesions (above the 6th thoracic ... 22897489 - Baroreflex function following spinal cord injury.. 1840179 - Consistent changes in the circadian rhythms of blood ...
more infohttp://www.biomedsearch.com/nih/Baroreflex-function-following-spinal-cord/22897489.html

Dynamic Aerobic Exercise Induces Baroreflex Improvement in Diabetic RatsDynamic Aerobic Exercise Induces Baroreflex Improvement in Diabetic Rats

However, the baroreflex bradycardic responses evaluated by linear regression (. ) or mean index methods (. ) were significantly ... Acute dynamic aerobic exercise did not alter baroreflex tachycardic responses in diabetic rats (. ). However, exercise induced ... Table 2: Baroreflex sensitivity evaluated by mean index method or by linear regression method in control and diabetic rats at ... Dynamic Aerobic Exercise Induces Baroreflex Improvement in Diabetic Rats. Luciana Jorge,1 Demilto Y. da Pureza,2 Danielle da ...
more infohttps://www.hindawi.com/journals/jdr/2012/108680/

Patent US20070161912 - Assessing autonomic activity using baroreflex analysis - Google PatentsPatent US20070161912 - Assessing autonomic activity using baroreflex analysis - Google Patents

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 ... Posture change is a trigger of the baroreflex. The baroreflex sensitivity is determined as the slope 612 of this plot in a time ... For example, the baroreflex analyzer 850 may make determination of autonomic imbalance using baroreflex sensitivity analysis ( ...
more infohttp://www.google.com/patents/US20070161912?dq=U.S.+patent+number+7,325,728

Patent US8594794 - Baroreflex activation therapy with incrementally changing intensity - Google PatentsuchePatent US8594794 - Baroreflex activation therapy with incrementally changing intensity - Google Patentsuche

... the baroreflex system of a patient using a baroreflex activation system with incrementally changing therapy intensity by ... activating a baroreflex system of the patient with a baroreflex activation device according to a baroreflex activation therapy ... activating a baroreflex system of the patient with a baroreflex activation device according to the baroreflex activation ... Baroreflex signals are used to activate a number of body systems which collectively may be referred to as baroreflex system 50 ...
more infohttp://www.google.de/patents/US8594794

Patent US8224437 - Baroreflex activation for sedation and sleep - Google PatentsPatent US8224437 - Baroreflex activation for sedation and sleep - Google Patents

Systems include at least one baroreflex activation device, at least one sensor for sensing physiological activity of the ... Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination ... for processing sensed data received from the sensor and for activating the baroreflex activation device. In some embodiments, ... Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. ...
more infohttp://www.google.com.au/patents/US8224437

Carotid baroreflex testing using the neck collar device.Carotid baroreflex testing using the neck collar device.

Baroreflex / physiology*. Cardiovascular Diseases / diagnosis, physiopathology*. Carotid Sinus / physiopathology*. Diagnostic ...
more infohttp://www.biomedsearch.com/nih/Carotid-baroreflex-testing-using-neck/19229465.html

Baroreflex control of sympathetic activity in experimental hypertensionBaroreflex control of sympathetic activity in experimental hypertension

Baroreflex control in high-renin hypertensive rats. Total aortic ligation between renal arteries is a useful model of high- ... Baroreflex control of sympathetic activity in sinoaortic denervation. Sinoaortic denervation (SAD) in animals has been used to ... 7. Mancia G & Mark AL (1983). Arterial baroreflexes in humans. In: Sheperd JT & Abboud FM (Editors), Handbook of Physiology. ... The role of the baroreflex in the short-term control of blood pressure ...
more infohttp://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X1998000900015

Improvement in Baroreflex Sensitivity in OSAS - Full Text View - ClinicalTrials.govImprovement in Baroreflex Sensitivity in OSAS - Full Text View - ClinicalTrials.gov

Improvement in Baroreflex Sensitivity in OSAS. The safety and scientific validity of this study is the responsibility of the ... The effect of long-term nocturnal therapy with continuous positive airway pressure (CPAP) on daytime baroreflex sensitivity ( ...
more infohttps://clinicaltrials.gov/ct2/show/NCT00284037

Patente US20090143834 - Automatic baroreflex modulation responsive to adverse event - Google PatentesPatente US20090143834 - Automatic baroreflex modulation responsive to adverse event - Google Patentes

The stimulator includes a pulse generator to provide a baroreflex stimulation signal adapted to provide a baroreflex therapy, ... signal indicative of the adverse event to change the baroreflex therapy from a first baroreflex therapy to a second baroreflex ... and a modulator to receive the signal indicative of the adverse event and modulate the baroreflex stimulation signal based on ... An aspect of the present subject matter relates to a system for providing baroreflex stimulation. An embodiment of the system ...
more infohttp://www.google.es/patents/US20090143834

Sympathetic and baroreflex abnormalities in the uncomplicated prediabetic stateSympathetic and baroreflex abnormalities in the uncomplicated prediabetic state

The adrenergic overdrive and the baroreflex impairment may thus participate at the disease progression, favoring the ... spontaneous baroreflex sensitivity, and a number of hemodynamic and metabolic variables, including homeostatic model assessment ... This neurogenic abnormality was associated with a reduced spontaneous baroreflex MSNA sensitivity (−3.20 ± 0.2 vs. −4.72 ± 0.2 ... MSNA values were directly and significantly related to HOMA index and inversely and significantly to baroreflex-MSNA ...
more infohttps://insights.ovid.com/jhype/201805000/00004872-201805000-00030

Carotid sinus baroreflex | definition of Carotid sinus baroreflex by Medical dictionaryCarotid sinus baroreflex | definition of Carotid sinus baroreflex by Medical dictionary

What is Carotid sinus baroreflex? Meaning of Carotid sinus baroreflex medical term. What does Carotid sinus baroreflex mean? ... Looking for online definition of Carotid sinus baroreflex in the Medical Dictionary? Carotid sinus baroreflex explanation free ... redirected from Carotid sinus baroreflex). Also found in: Dictionary, Encyclopedia.. Related to Carotid sinus baroreflex: ... Carotid sinus baroreflex , definition of Carotid sinus baroreflex by Medical dictionary https://medical-dictionary. ...
more infohttp://medical-dictionary.thefreedictionary.com/Carotid+sinus+baroreflex

Heart rate variability and baroreflex sensitivity in idiopathic dilated cardiomyopathy | HeartHeart rate variability and baroreflex sensitivity in idiopathic dilated cardiomyopathy | Heart

MEASUREMENT OF BAROREFLEX SENSITIVITY. After informed consent was obtained, baroreflex sensitivity was performed in 160 study ... Multivariate linear regression analysis revealed the following model for baroreflex sensitivity:. Baroreflex sensitivity = 1.27 ... Baroreflex sensitivity was then calculated as the slope of the linear regression line relating changes in RR intervals to ... The measure of determination R 2for this model was only 11%-that is, only 11% of the baroreflex sensitivity variance can be ...
more infohttp://heart.bmj.com/content/83/5/531

Prognostic value of baroreflex sensitivity testing after acute myocardial infarction. | HeartPrognostic value of baroreflex sensitivity testing after acute myocardial infarction. | Heart

When baroreflex sensitivity was adjusted for the effects of age and ventricular function baroreflex sensitivity was still ... Baroreflex sensitivity was appreciably reduced in these patients suffering arrhythmic events (1.73 SD (1.49) v 7.83 (4.5) ms/mm ... METHODS--As part of a prospective trial of risk stratification in post-infarction patients arterial baroreflex sensitivity, ... Baroreflex testing can be safely performed in the immediate post-infarction period. ...
more infohttp://heart.bmj.com/content/67/2/129

Automatic baroreflex modulation responsive to adverse event - Patent # 8712531 - PatentGeniusAutomatic baroreflex modulation responsive to adverse event - Patent # 8712531 - PatentGenius

... baroreflex stimulator. The baroreflex stimulator includes a driver to provide a control signal adapted to deliver a baroreflex ... change the baroreflex therapy from a first baroreflex therapy to a second baroreflex therapy. ... A system for providing baroreflex stimulation comprises a sensor to detect a parameter and provide a signal indicative of the ... baroreflex stimulator. The baroreflex stimulator includes a driver to provide a control signal adapted to deliver a baroreflex ...
more infohttp://www.patentgenius.com/patent/8712531.html

Frontiers | Post-ictal Modulation of Baroreflex Sensitivity in Patients With Intractable Epilepsy | NeurologyFrontiers | Post-ictal Modulation of Baroreflex Sensitivity in Patients With Intractable Epilepsy | Neurology

Keywords: epilepsy; autonomic nervous system; baroreflex function; baroreflex sensitivity; heart rate variability; SUDEP ... We tested how different types of seizures affect baroreflex sensitivity (BRS) and heart rate variability (HRV). We hypothesized ... We tested how different types of seizures affect baroreflex sensitivity (BRS) and heart rate variability (HRV). We hypothesized ... Baroreflex Function and Heart Rate Variability. Baroreflex sensitivity (BRS) was studied by analyzing the relationship between ...
more infohttps://www.frontiersin.org/articles/10.3389/fneur.2018.00793/full

Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa | Case Reports | PediatricsBaroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa | Case Reports | Pediatrics

Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa. Thilinie Rajapakse, Aleksandra Mineyko, ... Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa ... Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa ... Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa ...
more infohttps://pediatrics.aappublications.org/content/133/5/e1396..info

Baroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa | Case Reports | PediatricsBaroreflex Failure, Sympathetic Storm, and Cerebral Vasospasm in Fibulin-4 Cutis Laxa | Case Reports | Pediatrics

Baroreflexes buffer changes in arterial pressure to maintain homeostasis.4 The arterial baroreflex originates from stretch- ... baroreflex failure syndrome. BP - blood pressure. CT - computed tomography. HR - heart rate. RCVS - reversible cerebral ... Baroreflex failure: a neglected type of secondary hypertension. Neth J Med. 2004;62(5):151-155pmid:15366697. ... Although the adult literature includes cases of severe headache in baroreflex failure,1,2 we present the first case of a child ...
more infohttp://pediatrics.aappublications.org/content/133/5/e1396

Slow Breathing Increases Arterial Baroreflex Sensitivity in Patients With Chronic Heart Failure | CirculationSlow Breathing Increases Arterial Baroreflex Sensitivity in Patients With Chronic Heart Failure | Circulation

Arterial baroreflex sensitivity was measured by spectral analysis using the "α-angle" method.9 Briefly, the gain of the ... Baroreflex sensitivity can be enhanced significantly by slow breathing, both in health and in the presence of CHF. This seems ... Arterial baroreflex modulation of heart rate in chronic heart failure. Circulation. 1997; 96: 3450-3458. ... The aim of this study, therefore, was to assess whether the arterial baroreflex can be enhanced by a slow rate of breathing (6 ...
more infohttp://circ.ahajournals.org/content/105/2/143.full
  • Although the adult literature includes cases of severe headache in baroreflex failure, 1 , 2 we present the first case of a child with recurrent thunderclap headache and cerebral vasospasm with baroreflex failure secondary to vascular complications of a rare genetic connective tissue disorder. (aappublications.org)
  • 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)
  • These two methods have a high prognostic value, but do not offer a direct measure for describing the baroreflex. (google.com)
  • A special evaluation procedure of the BRS test also permits conclusions about the latent period (see list of prior art, No. ), 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)
  • Methods involve activating the baroreflex system to provide pain reduction, sedation, improved sleep or some combination thereof. (google.com.au)
  • 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. (google.es)
  • No major complications were noted with baroreflex testing and in particular no patients developed ischaemic or arrhythmic symptoms during the procedure. (bmj.com)
  • 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)
  • The aim of this study, therefore, was to assess whether the arterial baroreflex can be enhanced by a slow rate of breathing (6 breaths/min) in healthy subjects and in patients with CHF. (ahajournals.org)
  • Mean and variance of RRi and SBP, and baroreflex evaluated by phase, gain (α), and coherence (K 2 ) were determined. (scielo.br)
  • The aim of this study was to compare baroreflex among frail, prefrail, and nonfrail individuals, in supine and orthostatic positions. (scielo.br)
  • 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. (google.de)
  • Systems and methods provide baroreflex activation to treat or reduce pain and/or to cause or enhance sedation or sleep. (google.com.au)
  • A method for determining the baroreflex provides a non-invasive measurement of cardiac-interval periods, and a mathematical analysis of these measurement values on the basis of non-linear dynamic methods. (google.com)
  • 7 . The system of claim 1 , further comprising an implantable neural stimulator (NS) device and an implantable cardiac stimulator, wherein the implantable NS device includes the baroreflex stimulator and the implantable cardiac stimulator includes the adverse event detector, and both the implantable cardiac stimulator and the implantable NS device include transceivers to wirelessly communicate with each other. (google.es)
  • Sudden, severe, and life-threatening, the crises associated with baroreflex failure are diagnostically challenging, particularly in children, a population in which it has rarely been described. (aappublications.org)
  • We have demonstrated that, in the course of streptozotocin-(STZ-) induced experimental diabetes, baroreflex control of circulation was impaired [ 7 , 9 , 11 - 13 ]. (hindawi.com)
  • adjusting the baroreflex activation therapy in response to at least one of the magnitude of the change of the monitored parameter or the rate of change of the monitored physiological parameter. (google.de)
  • 2. The method of claim 1 , wherein the magnitude of a change for the physiological parameter affects adjusting of the baroreflex activation therapy. (google.de)
  • 3. The method of claim 2 , wherein if an increase in the magnitude of the monitored physiological parameter is determined to be a member of a class of large changes, then the baroreflex activation therapy is increased by a predetermined large step-size associated with large changes in the monitored physiologic parameter. (google.de)
  • 7. The method of claim 1 , further comprising determining a baroreflex activation therapy intensity step size associated with a class of change in the monitored physiological parameter magnitude. (google.de)
  • 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. (google.com.au)
  • An aspect of the present subject matter relates to a system for providing baroreflex stimulation. (google.es)
  • Baroreflex testing can be safely performed in the immediate post-infarction period. (bmj.com)
  • 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)