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).
Disturbance in the atrial activation that is caused by transient failure of impulse conduction from the SINOATRIAL NODE to the HEART ATRIA. It is characterized by a delayed in heartbeat and pauses between P waves in an ELECTROCARDIOGRAM.
Abnormally rapid heartbeats caused by reentry circuit in or around the SINOATRIAL NODE. It is characterized by sudden onset and offset episodes of tachycardia with a HEART RATE of 100-150 beats per minute. The P wave is identical to the sinus P wave but with a longer PR interval.
They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.
A small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus. It gives rise to the atrioventricular bundle of the conduction system of the heart.
The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioral phenomena.
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.
The chambers of the heart, to which the BLOOD returns from the circulation.
The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
The hemodynamic and electrophysiological action of the HEART ATRIA.
An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.
A subgroup of cyclic nucleotide-regulated ION CHANNELS of the superfamily of pore-loop cation channels that are opened by hyperpolarization rather than depolarization. The ion conducting pore passes SODIUM, CALCIUM, and POTASSIUM cations with a preference for potassium.
Irregular HEART RATE caused by abnormal function of the SINOATRIAL NODE. It is characterized by a greater than 10% change between the maximum and the minimum sinus cycle length or 120 milliseconds.
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.
A subgroup of cyclic nucleotide-regulated ION CHANNELS within the superfamily of pore-loop cation channels. They are expressed in OLFACTORY NERVE cilia and in PHOTORECEPTOR CELLS and some PLANTS.
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).
A condition caused by dysfunctions related to the SINOATRIAL NODE including impulse generation (CARDIAC SINUS ARREST) and impulse conduction (SINOATRIAL EXIT BLOCK). It is characterized by persistent BRADYCARDIA, chronic ATRIAL FIBRILLATION, and failure to resume sinus rhythm following CARDIOVERSION. This syndrome can be congenital or acquired, particularly after surgical correction for heart defects.
The hemodynamic and electrophysiological action of the RIGHT ATRIUM.
Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and nonexcitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.
Impaired conduction of cardiac impulse that can occur anywhere along the conduction pathway, such as between the SINOATRIAL NODE and the right atrium (SA block) or between atria and ventricles (AV block). Heart blocks can be classified by the duration, frequency, or completeness of conduction block. Reversibility depends on the degree of structural or functional defects.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
A heterogenous group of transient or low voltage activated type CALCIUM CHANNELS. They are found in cardiac myocyte membranes, the sinoatrial node, Purkinje cells of the heart and the central nervous system.
A group of homologous proteins which form the intermembrane channels of GAP JUNCTIONS. The connexins are the products of an identified gene family which has both highly conserved and highly divergent regions. The variety contributes to the wide range of functional properties of gap junctions.
Simple rapid heartbeats caused by rapid discharge of impulses from the SINOATRIAL NODE, usually between 100 and 180 beats/min in adults. It is characterized by a gradual onset and termination. Sinus tachycardia is common in infants, young children, and adults during strenuous physical activities.
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
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)
The hollow, muscular organ that maintains the circulation of the blood.
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.
Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.
Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.
A 43-kDa peptide which is a member of the connexin family of gap junction proteins. Connexin 43 is a product of a gene in the alpha class of connexin genes (the alpha-1 gene). It was first isolated from mammalian heart, but is widespread in the body including the brain.
Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.
Surgical excision of one or more lymph nodes. Its most common use is in cancer surgery. (From Dorland, 28th ed, p966)
An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.
Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).
Precursor cells destined to differentiate into cardiac myocytes (MYOCYTES, CARDIAC).
Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)
A drug combination that contains THEOPHYLLINE and ethylenediamine. It is more soluble in water than theophylline but has similar pharmacologic actions. It's most common use is in bronchial asthma, but it has been investigated for several other applications.
A group of slow opening and closing voltage-gated potassium channels. Because of their delayed activation kinetics they play an important role in controlling ACTION POTENTIAL duration.
Drugs that selectively bind to and activate beta-adrenergic receptors.
The electrical properties, characteristics of living organisms, and the processes of organisms or their parts that are involved in generating and responding to electrical charges.
A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.
Compounds with BENZENE fused to AZEPINES.
A diagnostic procedure used to determine whether LYMPHATIC METASTASIS has occurred. The sentinel lymph node is the first lymph node to receive drainage from a neoplasm.
Myosin type II isoforms found in cardiac muscle.
A device designed to stimulate, by electric impulses, contraction of the heart muscles. It may be temporary (external) or permanent (internal or internal-external).
A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.
Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.
Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.
Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).
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.
Changes in the organism associated with senescence, occurring at an accelerated rate.
Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.
Computer-based representation of physical systems and phenomena such as chemical processes.
A generic expression for any tachycardia that originates above the BUNDLE OF HIS.
A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
An electrogenic ion exchange protein that maintains a steady level of calcium by removing an amount of calcium equal to that which enters the cells. It is widely distributed in most excitable membranes, including the brain and heart.
A PEPTIDE of 22 amino acids, derived mainly from cells of VASCULAR ENDOTHELIUM. It is also found in the BRAIN, major endocrine glands, and other tissues. It shares structural homology with ATRIAL NATRIURETIC FACTOR. It has vasorelaxant activity thus is important in the regulation of vascular tone and blood flow. Several high molecular weight forms containing the 22 amino acids have been identified.
The craniosacral division of the autonomic nervous system. The cell bodies of the parasympathetic preganglionic fibers are in brain stem nuclei and in the sacral spinal cord. They synapse in cranial autonomic ganglia or in terminal ganglia near target organs. The parasympathetic nervous system generally acts to conserve resources and restore homeostasis, often with effects reciprocal to the sympathetic nervous system.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.
An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.
The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.
Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.
A tetrameric calcium release channel in the SARCOPLASMIC RETICULUM membrane of SMOOTH MUSCLE CELLS, acting oppositely to SARCOPLASMIC RETICULUM CALCIUM-TRANSPORTING ATPASES. It is important in skeletal and cardiac excitation-contraction coupling and studied by using RYANODINE. Abnormalities are implicated in CARDIAC ARRHYTHMIAS and MUSCULAR DISEASES.
Contractile activity of the MYOCARDIUM.
Transfer of a neoplasm from its primary site to lymph nodes or to distant parts of the body by way of the lymphatic system.
Compounds that specifically inhibit PHOSPHODIESTERASE 3.

Dual allosteric modulation of pacemaker (f) channels by cAMP and voltage in rabbit SA node. (1/896)

1. A Monod-Whyman-Changeux (MWC) allosteric reaction model was used in the attempt to describe the dual activation of 'pacemaker' f-channel gating subunits by voltage hyperpolarization and cyclic nucleotides. Whole-channel kinetics were described by assuming that channels are composed of two identical subunits gated independently according to the Hodgkin-Huxley (HH) equations. 2. The simple assumption that cAMP binding favours open channels was found to readily explain induction of depolarizing voltage shifts of open probability with a sigmoidal dependence on agonist concentration. 3. Voltage shifts of open probability were measured against cAMP concentration in macropatches of sino-atrial (SA) node cells; model fitting of dose-response relations yielded dissociation constants of 0.0732 and 0.4192 microM for cAMP binding to open and closed channels, respectively. The allosteric model correctly predicted the modification of the pacemaker current (If) time constant curve induced by 10 microM cAMP (13.7 mV depolarizing shift). 4. cAMP shifted deactivation more than activation rate constant curves, according to sigmoidal dose-response relations (maximal shifts of +22.3 and +13.4 mV at 10 microM cAMP, respectively); this feature was fully accounted for by allosteric interactions, and indicated that cAMP acts primarily by 'locking' f-channels in the open configuration. 5. These results provide an interpretation of the dual voltage- and cyclic nucleotide- dependence of f-channel activation.  (+info)

Regional differences in effects of E-4031 within the sinoatrial node. (2/896)

Effects of block of the rapid delayed rectifier K+ current (IK,r) by E-4031 on the electrical activity of small ball-like tissue preparations from different regions of the rabbit sinoatrial node were measured. The effects of partial block of IK,r by 0.1 microM E-4031 varied in different regions of the node. In tissue from the center of the node spontaneous activity was generally abolished, whereas in tissue from the periphery spontaneous activity persisted, although the action potential was prolonged, the maximum diastolic potential was decreased, and the spontaneous activity slowed. After partial block of IK,r, the electrical activity of peripheral tissue was more like that of central tissue under normal conditions. One possible explanation of these findings is that the density of IK,r is greater in the periphery of the node; this would explain the greater resistance of peripheral tissue to IK,r block and help explain why, under normal conditions, the maximum diastolic potential is more negative, the action potential is shorter, and pacemaking is faster in the periphery.  (+info)

Contribution of L-type Ca2+ current to electrical activity in sinoatrial nodal myocytes of rabbits. (3/896)

The role of L-type calcium current (ICa,L) in impulse generation was studied in single sinoatrial nodal myocytes of the rabbit, with the use of the amphotericin-perforated patch-clamp technique. Nifedipine, at a concentration of 5 microM, was used to block ICa,L. At this concentration, nifedipine selectively blocked ICa,L for 81% without affecting the T-type calcium current (ICa,T), the fast sodium current, the delayed rectifier current (IK), and the hyperpolarization-activated inward current. Furthermore, we did not observe the sustained inward current. The selective action of nifedipine on ICa,L enabled us to determine the activation threshold of ICa,L, which was around -60 mV. As nifedipine (5 microM) abolished spontaneous activity, we used a combined voltage- and current-clamp protocol to study the effects of ICa,L blockade on repolarization and diastolic depolarization. This protocol mimics the action potential such that the repolarization and subsequent diastolic depolarization are studied in current-clamp conditions. Nifedipine significantly decreased action potential duration at 50% repolarization and reduced diastolic depolarization rate over the entire diastole. Evidence was found that recovery from inactivation of ICa,L occurs during repolarization, which makes ICa,L available already early in diastole. We conclude that ICa,L contributes significantly to the net inward current during diastole and can modulate the entire diastolic depolarization.  (+info)

Electrophysiological effects of mexiletine in man. (4/896)

The electrophysiological effects of intravenous mexiletine in a dose of 200 to 250 mg given over 5 minutes, followed by continuous infusion of 60 to 90 mg per hour, were studied in 5 patients with normal conduction and in 20 patients with a variety of disturbances of impulse formation and conduction, by means of His bundle electrography, atrial pacing, and the extrastimulus method. In all but 2 patients the plasma level was above the lower therapeutic limit. Mexiletine had no consistent effects on sinus frequency and atrial refractoriness. The sinoatrial recovery time changed inconsistently in both directions; however, of the 5 patients in whom an increase was evident, 3 had sinus node dysfunction. In most patients mexiletine increased the AV nodal conduction time at paced atrial rates and shifted the Wenckebach point to a lower atrial rate. The effective refractory period of the AV node was not consistently influenced, while the functional refractory period increased in 12 out of 14 patients. The HV intervals increased by a mean of 11 ms in 8 patients and were unchanged in 17. Both the relative and effective refractory period of the His-Purkinje system increased after mexiletine. Non-cardiac side effects occurred in 7 out of 25 patients, and cardiac side effects, including one serious, in 2. The results indicate that mexiletine shares some electrophysiological properties with procainamide and quinidine, when given to patients with conduction defects, and that the drug should not be used in patients with pre-existing impairment of impulse formation or conduction. It has additional effects on AV nodal conduction which may be of value in the treatment of re-entrant tachycardias involving the AV node.  (+info)

The nerve supply and conducting system of the human heart at the end of the embryonic period proper. (5/896)

The nerve supply and conducting system were studied in a stage 23 human embryo of exceptional histological quality. The nerves on the right side arose from cervical sympathetic and from cervical and thoracic vagal filaments. Out of their interconnexions vagoxympathetic nerves emerged, which (1) sent a branch in front of the trachea to the aorticopulmonary ganglion, thereby supplying arterial and venous structures, and (2) formed the right sinal nerve, which supplied the sinu-atrial node, and gave filaments to the interatrial septum which could be traced to the atrioventricular node and pulmonary veins. The nerves on the left side arose similarly from cervical sympathetic and from cervical and thoracic vagal filaments. These formed several descending, ganglionated, vagosympathetic filaments that descended to the right of the arch of the aorta and entered the aorticopulmonary ganglion. Filaments leaving the ganglion supplied the pulmonary trunk, ascending aorta, interatrial septum, pulmonary veins, and, as the left sinal nerve, the fold of the left vena cava. The thoracic vagal filaments descended to the left of the arch of the aorta and supplied chiefly the arterial end of the heart. No thoracic sympathetic cardiac filaments were found. The sinu-atrial node began as a crescentic mass in front of the lower part of the superior vena cava. It gradually extended on each side of the superior vena cava and came to form its posterior wall at a more caudal level. The atrial myocardium that formed the septum spurium, venous valves, and interatrial septum could be traced from the sinu-atrial to the atrioventricular node. Myocardium also encircled the atrial aspects of the atrioventricular orifices, and could be traced caudally to the atrioventricular nde. The atrioventricular node was a conspicuous mass in the anterior and lower part of the interatrial septum, from which a clearly defined bundle left to enter the interventricular septum. Right and left limbs were observed, the former being a rounded bundle that passed immediately in front of the root of the aorta.  (+info)

Defibrillation-guided radiofrequency ablation of atrial fibrillation secondary to an atrial focus. (6/896)

OBJECTIVES: Our aim was to evaluate a potential focal source of atrial fibrillation (AF) by unmasking spontaneous early reinitiation of AF after transvenous atrial defibrillation (TADF), and to describe a method of using repeated TADF to map and ablate the focus. BACKGROUND: Atrial fibrillation may develop secondary to a rapidly discharging atrial focus that the atria cannot follow synchronously, with suppression of the focus once AF establishes. Focus mapping and radiofrequency (RF) ablation may be curative but is limited if the patient is in AF or if the focus is quiescent. Early reinitiation of AF has been observed following defibrillation, which might have a focal mechanism. METHODS: We performed TADF in patients with drug-refractory lone AF using electrodes in the right atrium (RA) and the coronary sinus. When reproducible early reinitiation of AF within 2 min after TADF was observed that exhibited a potential focal mechanism, both mapping and RF ablation were performed to suppress AF reinitiation. Clinical and ambulatory ECG monitoring was used to assess AF recurrence. RESULTS: A total of 44 lone AF patients (40 men, 4 women; 32 persistent, 12 paroxysmal AF) with a mean age of 58+/-13 years underwent TADF. Sixteen patients had early reinitiation of AF after TADF, nine (20%; 5 paroxysmal) exhibited a pattern of focal reinitiation. Earliest atrial activation was mapped to the right superior (n = 4) and the left superior (n = 3) pulmonary vein, just inside the orifice, in the seven patients who underwent further study. At the onset of AF reinitiation, the site of earliest activation was 86+/-38 ms ahead of the RA reference electrogram. The atrial activities from this site were fragmented and exhibited progressive cycle-length shortening with decremental conduction to the rest of the atrium until AF reinitiated. Radiofrequency ablation at the earliest activation site resulted in suppression of AF reinitiation despite pace-inducibility. Improved clinical outcome was observed over 8+/-4 months' follow-up. CONCLUSIONS: Transvenous atrial defibrillation can help to unmask, map, and ablate a potential atrial focus in patients with paroxysmal and persistent AF. A consistent atrial focus is the cause of early reinitiation of AF in 20% of patients with lone AF, and these patients may benefit from this technique.  (+info)

Heterogeneity of 4-aminopyridine-sensitive current in rabbit sinoatrial node cells. (7/896)

The electrophysiological properties of sinoatrial (SA) node pacemaker cells vary in different regions of the node. In this study, we have investigated variation of the 4-aminopyridine (4-AP)-sensitive current as a function of the size (as measured by the cell capacitance) of SA node cells to elucidate the ionic mechanisms. The 10 mM 4-AP-sensitive current recorded from rabbit SA node cells was composed of transient and sustained components (Itrans and Isus, respectively). The activation and inactivation properties [activation: membrane potential at which conductance is half-maximally activated (Vh) = 19.3 mV, slope factor (k) = 15.0 mV; inactivation: Vh = -31.5 mV, k = 7.2 mV] as well as the density of Itrans (9.0 pA/pF on average at +50 mV) were independent of cell capacitance. In contrast, the density of Isus (0.97 pA/pF on average at +50 mV) was greater in larger cells, giving rise to a significant correlation with cell capacitance. The greater density of Isus in larger cells (presumably from the periphery) can explain the shorter action potential in the periphery of the SA node compared with that in the center. Thus variation of the 4-AP-sensitive current may be involved in regional differences in repolarization within the SA node.  (+info)

Contribution of baroreceptors and chemoreceptors to ventricular hypertrophy produced by sino-aortic denervation in rats. (8/896)

1. To test whether sino-aortic denervation (SAD)-induced right ventricular hypertrophy (RVH) is a consequence of baroreceptor or chemoreceptor denervation, we compared the effects of aortic denervation (AD), carotid denervation (CD), SAD and a SAD procedure modified to spare the carotid chemoreceptors (mSAD), 6 weeks after denervation surgery in rats. A sham surgery group served as the control. 2. The blood pressure (BP) level was unaffected by AD, CD or SAD, but increased (9 %) following mSAD. The mean heart rate level was not affected. Short-term BP variability was elevated following AD (81 %), SAD (144 %) and mSAD (146 %), but not after CD. Baroreflex heart rate responses to phenylephrine were attenuated in all denervation groups. 3. Significant RVH occurred only following CD and SAD. These procedures also produced high mortality (CD and SAD) and significant increases in right ventricular pressures and haematocrit (CD). 4. Significant left ventricular hypertrophy occurred following CD, SAD and mSAD. Normalized left ventricular weight was significantly correlated with indices of BP variability. 5. These results suggest that SAD-induced RVH is a consequence of chemoreceptor, not baroreceptor, denervation. Our results also demonstrate that a mSAD procedure designed to spare the carotid chemoreceptors produced profound baroreflex dysfunction and significant left, but not right, ventricular hypertrophy.  (+info)

Modification of the effects of histamine and norepinephrine on the sinoatrial node pacemaker by potassium and calcium Academic Article ...
Computational analysis of the human sinus node action potential: model development and effects of mutations[3] The sinoatrial node (SAN) is the normal pacemaker of the mammalian heart. Over several decades, a large amount of data on the ionic mechanisms underlying the spontaneous electrical activity of SAN pacemaker cells has been obtained, mostly in experiments on single cells isolated from rabbit SAN. This wealth of data has allowed the development of mathematical models of the electrical activity of rabbit SAN pacemaker cells. Our aim was to construct a more comprehensive model of the electrical activity of a human SAN pacemaker cell, using recently obtained electrophysiological data from human SAN pacemaker cells. We based our model on the recent Severi-DiFrancesco model of a rabbit SAN pacemaker cell. The action potential and calcium transient of the resulting model are close to the experimentally recorded values: the model has a much smaller funny current (If ) than do rabbit cells, but ...
Background- Homozygous mutant mice with a defect of klotho gene expression (kl/kl) show multiple age-related disorders and premature death from unknown causes.. Methods and Results- The kl/kl mice subjected to 20-hour restraint stress showed a high rate (20/30) of sudden death, which was associated with sinoatrial node dysfunction (conduction block or arrest). Heart rate and plasma norepinephrine of kl/kl mice, unlike those of wild-type (WT) mice, failed to increase during the stress. Intrinsic heart rate after pharmacological blockade of autonomic nerves in kl/kl mice was significantly lower than that in WT mice (380±33 versus 470±44 bpm; n=7). The sinus node recovery time after an overdrive pacing (600 bpm, 30 seconds) in kl/kl mice was significantly longer than in WT mice (392±37 versus 233±24 ms; n=6). In isolated sinoatrial node preparations, the positive chronotropic effect of isoproterenol was significantly less, whereas the negative chronotropic effect of acetylcholine was ...
In the century since the discovery by Keith and Flack of the sinoatrial node in the mole heart, a detailed mosaic of its cellular, anatomic, and electrophysiological properties has emerged. The human sinus node has been found to be anatomically constant and well localized, occupying an approximately 10-mm subepicardial region on the sulcus terminalis at the superior cavo-atrial junction.1 Histologically, its ultrastructure of central P cells (likely corresponding to the leading pacemaker site) and outer transitional zone merging with surrounding atrial myocardium have been well characterized.1 Great progress also has been made in defining the ionic mechanisms responsible for the sinoatrial action potential and its spontaneous pacemaker activity, including important contributory roles for ICa,L, Ik, and the funny current, If.1 This morphologically discrete, unifocal sinus node is not the exclusive force behind clinical sinus rhythm, however. Detailed animal and human mapping has demonstrated that ...
Rationale: Autonomic nerves from sinoatrial node (SAN) ganglia are known to regulate SAN function. However, it is unclear whether remote pulmonary vein ganglia (PVG) also modulate SAN pacemaker rhythm. Objective: To investigate whether in the mouse heart PVG modulate SAN function. Methods and Results: In hearts from 45 C57BL and 7 Connexin40+/GFP mice, we used tyrosine-hydroxylase (TH) and choline-acetyltransferase (ChAT) immunofluorescence labeling to characterize adrenergic and cholinergic elements, repectively, within the PVG and SAN. PVG project postganglionic nerves to the SAN. TH and ChAT stained nerves, enter the SAN as an extensive, dense mesh-like neural network. Neurons in PVG are biphenotypic, containing ChAT and TH positive neurons. In Langendorff-perfused hearts, we compared effects of electrical stimulation of PVG, posterior (PRCVG) and anterior right vena cava ganglia (ARCVG) using 200-2000 ms trains of pulses (300μs, 0.2-0.6mA, 200Hz). Sympathetic and/or parasympathetic ...
The aim of this study was to investigate possible regulation of the hyperpolarization-activated current (I(f)) by cytosolic calcium in guinea-pig sino-atrial (SA) node cells. Isolated SA node cells were superfused with physiological saline solution (36 degrees C) and the perforated patch voltage-clamp technique used to record I(f) activated by hyperpolarizing voltage steps. A 10-min loading of SA node cells with the calcium chelator BAPTA (using 10 microM BAPTA-AM) significantly reduced the amplitude of I(f) at all potentials studied (69+/-8% at -80 mV, n=6). BAPTA loading also shifted the voltage of half-activation (V(h)) of the conductance from -83+/-2 mV in control to -93+/-2 mV in BAPTA (n=6) without significantly altering the slope of activation. The calmodulin antagonists W-7 (10 microM), calmidazolium (25 microM) and ophiobolin A (20 microM) caused similar reductions in I(f) amplitude (73+/-4, 86+/-9 and 59+/-6% at -80 mV, n=6, 5 and 4, respectively) and shifts in V(h) (11+/-3, 14+/-3 and 8+/-2
RATIONALE: Inositol 1,4,5-trisphosphate receptors (IP(3)Rs) have been implicated in the generation of arrhythmias and cardiac muscle nuclear signaling. However, in the mammalian sinoatrial node (SAN), where the heart beat originates, the expression and functional activity of IP(3)Rs have not been investigated. OBJECTIVES: To determine whether SAN express IP(3)Rs and which isoforms are present. To examine the response of the SAN to IP(3)R agonists and antagonist, and the potential role played by IP(3)Rs in cardiac pacemaking. METHODS AND RESULTS: The expression and distribution of IP(3)Rs were studied by reverse-transcription polymerase chain reaction, Western blotting, and immunolabeling. Ca(2+) signaling and electric activity in intact mouse SAN were measured with Ca(2+)-sensitive fluorescent dyes. We found that although the entire SAN expressed three IP(3)R mRNA isoforms, the type II IP(3)R (IP(3)R2) was the predominant protein isoform detected by Western blot using protein extracts from the SAN,
TY - JOUR. T1 - Synergistic dual automaticity in sinoatrial node cell and tissue models. AU - Zhang, Hong. AU - Joung, Boyoung. AU - Shinohara, Tetsuji. AU - Mei, Xi. AU - Chen, Peng-Sheng. AU - Lin, Shien-Fong. PY - 2010. Y1 - 2010. N2 - Background: The mechanism of sinoatrial node (SAN) automaticity is traditionally attributed to membrane ion currents. Recent evidence indicates spontaneous sarcoplasmic reticulum (SR) Ca2+ cycling also plays an important role. Methods and Results: A computer simulation on SAN cell and 1D tissue model was performed. In the SAN cells, SR Ca2+ cycling broadly modulated the sinus rate from 1.74 Hz to 3.87 Hz. Shortening of the junctional SR refilling time and increase of SR Ca2+ release were responsible for sinus rate acceleration. However, under the fast SR Ca2+ cycling, decreased L-type Ca2+ current (ICaL) resulted in irregular firing. When Ca2+ cycling was suppressed, If and ICaT both acted to stabilize the pacemaker rhythm, but ICaT had less effect than If. At ...
The advent of Ca2+ sensitive indicators, coupled to confocal imaging with simultaneous measurement of membrane potential, has permitted the detection of LCRs beneath the cell membrane during diastolic depolarization. Recent studies1,2,12 have shown that LCRs during diastolic depolarization activate NCX, which produces a large inward current1,9,19 in pacemaker cells, and enhances the rate of the later part of the diastolic depolarization.. The first novel finding of the present study is that the occurrence of LCRs during diastolic depolarization in rabbit sinoatrial nodal cells does not require the concomitant change in membrane potential. Thus, local LCRs occur in saponin skinned cells bathed at physiological [Ca2+] and during acute voltage clamp of spontaneously beating cells (Figures 1 and 3⇑). During the initial stage of voltage clamp, ie, the first would-be cycle, when SR Ca2+ load and RyR inactivation are the same as during the prior spontaneous beating, the LCR characteristics are ...
TY - JOUR. T1 - The calcium and voltage clocks in sinoatrial node automaticity. AU - Joung, Boyoung. AU - Ogawa, Masahiro. AU - Lin, Shien Fong. AU - Chen, Peng Sheng. PY - 2009/6/1. Y1 - 2009/6/1. N2 - Recent evidence indicates that the voltage (cyclic activation and deactivation of membrane ion channels) and Ca2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca2+ release) jointly regulate sinoatrial node (SAN) automaticity. Since the intact SAN is a heterogeneous structure that includes multiple different cell types interacting with each other, the relative importance of the voltage and Ca2+ clocks for pacemaking may be variable in different regions of the SAN. Recently, we performed optical mapping in isolated and Langendorff-perfused canine right atria. We mapped the intracellular calcium (Cai) and membrane potentials of the intact SAN simultaneously. Using previously described criteria of the timing of the late diastolic Cai elevation (LDCAE) relative to the action potential upstroke ...
Methods and Results: Distribution of Islet-1+ cells in adult heart was investigated using transgenic mice with nuclear β-galactosidase inserted into the Islet-1 locus. nLacZ-positive cells were only present in 3 regions of the adult heart: clusters in the interatrial septum, scattered within the wall of the great vessels, and a strictly delimited cluster between right atrium and superior vena cava. Islet-1+ cells in the first type of clusters coexpressed markers for parasympathetic neurons. Positive cells in the great arteries coexpressed smooth muscle actin and β-myosin heavy chain, indicating a smooth muscle cell identity. Very few Islet-1+ cells within the outflow tract expressed the cardiomyocyte marker α-actinin. Islet-1+ cells in the right atrium coexpressed the sinoatrial node pacemaker cell marker HCN4. Cell number and localization remained unchanged between 1 to 18 months of age. Consistently Islet-1 mRNA was detected in human sinoatrial node. Islet-1+ cells could not be detected in ...
ABSTRACT: INTRODUCTION: Cardiac multicellular modeling has traditionally focused on ventricular electromechanics. More recently, models of the atria have started to emerge, and there is much interest in addressing sinoatrial node structure and function. METHODS AND RESULTS: We implemented a variety of one-dimensional sinoatrial models consisting of descriptions of central, transitional, and peripheral sinoatrial node cells, as well as rabbit or human atrial cells. These one-dimensional models were implemented using CMISS on an SGI Origin 2000 supercomputer. Intercellular coupling parameters recorded in experimental studies on sinoatrial node and atrial cell-pairs under-represent the electrotonic interactions that any cardiomyocyte would have in a multidimensional setting. Unsurprisingly, cell-to-cell coupling had to be scaled-up (by a factor of 5) in order to obtain a stable leading pacemaker site in the sinoatrial node center. Further critical parameters include the gradual increase in ...
The sinoatrial node (SA node), also known as sinus node, is a group of cells located in the wall of the right atrium of the heart. These cells have the ability to spontaneously produce an electrical impulse (action potential; see below for more details), that travels through the heart via the electrical conduction system (see figure 1) causing it to contract. In a healthy heart, the SA node continuously produces action potential, setting the rhythm of the heart and so is known as the hearts natural pacemaker. The rate of action potential production (and therefore the heart rate) is influenced by nerves that supply it. The sinoatrial node is a banana-shaped structure that varies in size, usually between 10-30 millimeters (mm) long, 5-7 mm wide, and 1-2 mm deep. The SA node is located in the wall (myocardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum (hence sino- + atrial). It is positioned roughly between a groove called the ...
How is isolated rabbit sino-atrial abbreviated? SA stands for isolated rabbit sino-atrial. SA is defined as isolated rabbit sino-atrial very rarely.
TY - JOUR. T1 - Heart failure differentially modulates natural (Sinoatrial node) and ectopic (pulmonary veins) pacemakers. T2 - Mechanism and therapeutic implication for atrial fibrillation. AU - Chan, Chao Shun. AU - Lin, Yung Kuo. AU - Chen, Yao Chang. AU - Lu, Yen Yu. AU - Chen, Shih Ann. AU - Chen, Yi Jen. PY - 2019/7/1. Y1 - 2019/7/1. N2 - Heart failure (HF) frequently coexists with atrial fibrillation (AF) and dysfunction of the sinoatrial node (SAN), the natural pacemaker. HF is associated with chronic adrenergic stimulation, neurohormonal activation, abnormal intracellular calcium handling, elevated cardiac filling pressure and atrial stretch, and fibrosis. Pulmonary veins (PVs), which are the points of onset of ectopic electrical activity, are the most crucial AF triggers. A crosstalk between the SAN and PVs determines PV arrhythmogenesis. HF has different effects on SAN and PV electrophysiological characteristics, which critically modulate the development of AF and sick sinus syndrome. ...
TY - JOUR. T1 - Abnormal response of superior sinoatrial node to sympathetic stimulation is a characteristic finding in patients with atrial fibrillation and symptomatic bradycardia. AU - Joung, Boyoung. AU - Hwang, Hye Jin. AU - Pak, Hui Nam. AU - Lee, Moon Hyoung. AU - Shen, Changyu. AU - Lin, Shien Fong. AU - Chen, Peng Sheng. PY - 2011/12. Y1 - 2011/12. N2 - Background-We hypothesized that unresponsiveness of superior sinoatrial node (SAN) to sympathetic stimulation is strongly associated with the development of symptomatic bradycardia in patients with atrial fibrillation (AF). Methods and Results-We performed 3D endocardial mapping in healthy controls (group 1, n=10) and patients with AF without (group 2, n=57) or with (group 3, n=15) symptomatic bradycardia at baseline and during isoproterenol infusion. Corrected SAN recovery time was abnormal in 0%, 11%, and 36% of groups 1, 2, and 3, respectively (P=0.02). At baseline, 90%, 26%, and 7% (P,0.001) of the patients had multicentric SAN ...
TY - JOUR. T1 - Measurement of funny current (I(f)) channel mRNA in human atrial tissue. T2 - Correlation with left atrial filling pressure and atrial fibrillation. AU - Lai, Ling Ping. AU - Su, Ming Jai. AU - Lin, Jiunn Lee. AU - Tsai, Chang Her. AU - Lin, Fang Yue. AU - Chen, Yih Sharng. AU - Hwang, Juey Jen. AU - Stephen Huang, Shoei K.. AU - Tseng, Yung Zu. AU - Lien, Wen Pin. PY - 1999/1/1. Y1 - 1999/1/1. N2 - Introduction: The funny current (I(f)) contributes to phase IV spontaneous depolarization in cardiac pacemaker tissue. Enhanced I(f) activity in myocardial tissue may lead to increased automaticity and therefore tachyarrhythmia. We measured the amount of I(f) activity in the messenger ribonucleic acid (mRNA) in human atrial tissue and correlated the mRNA amount to left atrial filling pressure and atrial fibrillation (AF). Methods and Results: A total of 34 patients undergoing open heart surgery were included (15 men and 19 women, aged 55 ± 10 years). Atrial tissue was obtained from ...
Free, official information about 2012 (and also 2013-2015) ICD-9-CM diagnosis code 427.81, including coding notes, detailed descriptions, index cross-references and ICD-10-CM conversion.
Cardiac pacemaker cells of the sinoatrial node initiate and maintain the rhythmic beating of the heart. This function requires that pacemaker cells be insulated...
We studied the effects of cholinergic agonists on slow delayed-rectifier K+ current (IKs) in isolated cells from the sino-atrial node (SAN) region of guinea pig heart, using patch-clamp procedures. Carbachol (5 nM to 10 microM) inhibited IKs in guinea pig SAN cells in the absence of previous beta-adrenergic stimulation and in cells pretreated with 8-(4-chlorophenylthio)-cAMP. Neither the muscarinic antagonist atropine nor the nicotinic antagonist hexamethonium antagonized carbachol inhibition of the current. Similar results were obtained with other cholinergic agonists. Cholinergic stimulation of the muscarinic K+ current was successfully antagonized by atropine in SAN cells where inhibition of IKs persisted. Therefore, the lack of antagonist effects on inhibition of IKs cannot be attributed to either an absence of muscarinic cholinoceptors on SAN cells or a loss of antagonist activity under our experimental conditions. These data demonstrate that cholinergic agonists, including the endogenous ...
In a randomized, observer-blind study, the effect of incremental doses of pindolol 0.001, 0.002, 0.003, and 0.004 mg/kg IV and propranolol 0.01, 0.02, 0.03, and 0.04 mg/kg IV on SA nodal recovery time (SNRT) and atrioventricular conduction interval (AH) was assessed in 20 patients (15 men and 5 women age range thirty to seventy-two, mean age fifty-three). AH and His bundle-to-ventricle (HV) intervals and SNRT were measured at spontaneous heart rate and at incremental atrial pacing rates (80, 100, 120, 140 bpm). Both drugs caused significant beta blockade as estimated by the percentage suppression of heart rate increment induced by 3 mcg isoproterenol administered intravenously (pindolol 67.6±5.3%, ...
Free Online Library: Sinoatrial node artery arising from posterolateral branch of right coronary artery: definition by screening consecutive 1500 coronary angiographies/Sag koroner arter posterolateral dalindan cikan sinoatriyal nod arteri: Ardisik 1500 koroner anjiyografi taramasi ile tanimlama.(Original Investigation/Ozgun Arastirma) by The Anatolian Journal of Cardiology (Anadolu Kardiyoloji Dergisi); Health, general Angiography
Spontaneous activation and contraction of the heart are a consequence of the specialized pacemaking tissue in these anatomic locales. As described in Chap. 238, action potentials in the heart are regionally heterogeneous. The action potentials in cells isolated from nodal tissue are distinct from those recorded from atrial and ventricular myocytes (Fig. 239-1). The complement of ionic currents present in nodal cells results in a less negative resting membrane potential compared with atrial or ventricular myocytes. Electrical diastole in nodal cells is characterized by slow diastolic depolarization (phase 4), which generates an action potential as the membrane voltage reaches threshold. The action potential upstrokes (phase 0) are slow compared with atrial or ventricular myocytes, being mediated by calcium rather than sodium current. Cells with properties of SA and AV nodal tissue are electrically connected to the remainder of the myocardium by cells with an electrophysiologic phenotype between ...
OBJECTIVE: The L-type Ca(2+) current (I(Ca,L)) contributes to the generation and modulation of the pacemaker action potential (AP). We investigated facilitation of I(Ca,L) in sino-atrial cells. METHODS: Facilitation was studied in regularly-beating cells isolated enzymatically from young albino rabbits (0.8-1 kg). We used the whole-cell patch-clamp technique to vary the frequency of the test depolarizations evoked at -10 mV or the conditioning diastolic membrane potential prior to the test pulse. RESULTS: High frequencies (range 0.2-3.5 Hz) slowed the decay kinetics of I(Ca,L) evoked from a holding potential (HP) of -80 mV in 68% of cells resulting in a larger Ca(2+) influx during the test pulse. The amount of facilitation increased progressively between 0.2 and 3.0 Hz. When the frequency was changed from 0.1 to 1 Hz, the averaged increase in the time integral of I(Ca,L) was 27+/-7% (n=22). Application of conditioning voltages between -80 and -50 mV induced similar facilitation of I(Ca,L) in 73% of
Antibodies for proteins involved in SA node cell to atrial cardiac muscle cell communication pathways, according to their Panther/Gene Ontology Classification
The sinoatrial node (SAN) is the normal pacemaker of the mammalian heart. Over several decades, a large amount of data on the ionic mechanisms underlying the spontaneous electrical activity of SAN pacemaker cells has been obtained, mostly in experiments on single cells isolated from rabbit SAN. This allowed the development of comprehensive mathematical models of ...
Enhanced cardiac automaticity refers to the accelerated generation of an action potential by either normal pacemaker tissue (enhanced normal automaticity) or by abnormal tissue within the myocardium (abnormal automaticity). The discharge rate of norm
ible dose of sildenafil during 1 month. In patients with Since endothelial dysfunction is associated with vas- CHF, sildenafil significantly reduced blood pressure, cular inflammation, platelet activation, and rapid pro- resting heart rate and attenuated the heart rate incre- gression of atherosclerosis and its adverse events, strate- ment (6-min treadmill-walking test and maximal exer- gies that enhance NO bioavailability may have a positive cise test, Figure 3) which was attributed to the modula- impact on outcomes in patients with coronary artery dis- tion of the effects of the NO-cGMP pathway on the ease (CAD). Therefore, Halcox et al. [40] hypothesized pacemaker activity of sinoatrial node cells [43]. More- that PDE 5 inhibition with sildenafil may abrogate coro- nary and peripheral vascular endothelial dysfunction in cise and increased the maximal exercise capacity. Treat- patients with CAD, inhibit platelet activation, and ame- ment was associated with more adverse symptoms, liorate ...
Background. The ischemic damage of the sinus node (SN) is a well known cause of cardiac arrhythmias and can be a consequence of any flow abnormality in the sinus node artery (SNA). Accordingly we aimed this retrospective study to: (1) evaluate the suitability of the standard coronary angiography to study the SNA and (2) determine if the percentage of subjects with a positive retrospective history of supra-ventricular arrhythmias (SVA) differs in patients with normal and diseased SNA ascertained at the time of coronary angiography.Methods and Results. Out of the 541 coronary angiograms reviewed the SNA was visible for its entire course in 486 cases (89.8%). It was found to arise from the right side of the coronary circulation in 266 cases (54.7%) slightly more often than from the left, 219 cases (45.1%). One patient had 2 distinct SNA arising from either side of the coronary circulation. For the second objective, we studied the 333 patients with: (a) coronary artery disease (CAD), (b) properly evaluable
Mladen Boban, John L. Atlee, Martin Vicenzi, John P. Kampine, Zeljko J. Bosnjak; Anesthetics and Automaticity in Latent Pacemaker Fibers: IV. Effects of Isoflurane and Epinephrine or Norepinephrine on Automaticity of Dominant and Subsidiary Atrial Pacemakers in the Canine Heart. Anesthesiology 1993;79(3):555-562. Download citation file:. ...
Automaticity refers to a cardiac muscle cell firing off an impulse on its own. All of the cells in the heart have the ability to initiate an action potential; however, only some of these cells are designed to routinely trigger heart beats. These cells are found in the conduction system of the heart and include the SA node, AV node, Bundle of His and Purkinje fibers. The sinoatrial node is a single specialized location in the atrium that has a higher automaticity (a faster pacemaker) than the rest of the heart and, therefore, is usually responsible for setting the heart rate and initiating each heart beat. Any part of the heart that initiates an impulse without waiting for the sinoatrial node is called an ectopic focus and is, by definition, a pathological phenomenon. This may cause a single premature beat now and then, or, if the ectopic focus fires more often than the sinoatrial node, it can produce a sustained abnormal rhythm. Rhythms produced by an ectopic focus in the atria, or by the ...
Wandering atrial pacemaker (WAP) is an atrial arrhythmia that occurs when the natural cardiac pacemaker site shifts between the sinoatrial node (SA node), the atria, and/or the atrioventricular node (AV node). This shifting of the pacemaker from the SA node to adjacent tissues is identifiable on ECG Lead II by morphological changes in the P-wave; sinus beats have smooth upright P waves, while atrial beats have flattened, notched, or diphasic P-waves. It is often seen in the very young, very old, and in athletes, and rarely causes symptoms or requires treatment.[citation needed] Wandering pacemaker is usually caused by varying vagal tone. With increased vagal tone the SA Node slows, allowing a pacemaker in the atria or AV Nodal area, which may briefly become slightly faster. After vagal tone decreases, the SA Node assumes its natural pace. A wandering atrial pacemaker, also termed multifocal atrial rhythm, is present when there are three or more ectopic foci within the atrial myocardium that ...
Sinoatrial nodal cells (SANCs) generate spontaneous action potentials (APs) that control the cardiac rate. The brain modulates SANC automaticity, via the autonomic nervous system, by stimulating membrane receptors that activate (adrenergic) or inactivate (cholinergic) adenylyl cyclase (AC). However, these opposing afferents are not simply additive. We showed that activation of adrenergic signaling increases AC-cAMP/PKA signaling, which mediates the increase in the SANC AP firing rate (i.e., positive chronotropic modulation). However, there is a limited understanding of the underlying internal pacemaker mechanisms involved in the crosstalk between cholinergic receptors and the decrease in the SANC AP firing rate (i.e., negative chronotropic modulation). We hypothesize that changes in AC-cAMP/PKA activity are crucial for mediating either decrease or increase in the AP firing rate and that the change in rate is due to both internal and membrane mechanisms. In cultured adult rabbit pacemaker cells infected
Under normal physiologic conditions, the dominant pacemaker cells of the heart lie within the sinoatrial node; in adults, these pacemaker cells fire at rates between 60 to 100 beats per minute (i.e., faster than cells in any other cardiac region, See Figure 3). Even at rest, modulation by the autonomic nervous system dominates, with the primary drive from the parasympathetics; at rest or during sleep, the sinoatrial nodal rate decreases to about 75 beats per minute (bpm) or even slower.. In addition to pacemaker cells of the sinoatrial node, other cells within the conduction system are capable of developing autorhythmicity, specifically those within the atrioventricular node (junction region) and His-Purkinje system. Yet, rhythms generated within these cells are in a much lower range (25 to 55 bpm), hence not altering the intrinsic atrial rates (Figure 2). These lower rate rhythms are commonly referred to as ventricular escape rhythms and are important for patient survival, since they maintain ...
The objective of the study was to evaluate the effect of ibutilide on canine cardiac sinoatrial and atrioventricular nodes (AVNs). For this purpose, 18 mongrel dogs were injected intravenously with ibutilide and the changes in heart rate, sinus node recovery time, and AVN were measured. Our data show that ibutilide administration caused significant suppression of the sinus atrial node, the peak response time was 20-30 min, and the heart rate was restored to pre-drug administration level. After receiving ibutilide, 1 animal had a 5 s sinus pause, and after 5 min of ibutilide administration, 1 dog showed 2:1 atrioventricular conduction. Therefore, it was concluded that ibutilide had a suppressive effect on the sinoatrial node and AVN. ...
Abstract:. Background: For chronic kidney disease patients undergoing maintenance hemodialysis (HD), the risk to die from sudden cardiac death (SCD) is 14x higher compared to patients with a history of cardiovascular disease and normal kidney function. Traditional SCD risk factors cannot explain this high rate. Two recent human studies using implantable loop recorders surprisingly point towards bradycardia and asystole as the prevailing arrhythmias causing SCD in HD patients. This suggests a decisive role of the sinus node. Objective: To identify the effect of altered electrolyte levels (as systematically occurring in HD patients) on pacemaking in a computational model of human sinus node cells. Methods: We enhanced the Fabbri et al. model of human sinus node cells to account for the dynamic intracellular balance of all considered electrolytes. The model was exposed to clinically relevant extracellular electrolyte concentrations of potassium, sodium, and calcium to study their effect on ...
Looking for nodal artery? Find out information about nodal artery. blood vessel that conveys blood away from the heart heart, muscular organ that pumps blood to all parts of the body. The rhythmic beating of the heart is a... Explanation of nodal artery
Properties of the cardiac muscle AUTOMATICITY CONDUCTIVITY CONTRACTILITY EXCITABILITY REFRACTORY PERIODS 1. AUTOMATICITY is the unique ability of the cells in the SA node (pacemaker cells) to generate an action potential without being stimulated.
The sinoatrial node (SAN) is the normal pacemaker of the mammalian heart. Over several decades, a large amount of data on the ionic mechanisms underly...
Cardiovascular disease is a significant health concern. Risk factors include hypertension, obesity, dyslipidemia and smoking. Women who are postmenopausal are at an increased risk of heart disease. Here is the latest research for risk factors of cardiovascular disease. ...
We have investigated the concentration-dependent modulation, by the novel class III antiarrhythmic compound NE-10064, of the delayed potassium channel current Iks in isolated guinea pig sinoatrial nodal (SAN) and ventricular cells. At concentrations greater than 1 micron, the drug potently inhibited Iks in each of the cell types investigated. The concentration-dependent inhibition of Iks (IC50 = 700 nM) was the same in ventricular and SAN cells. At near-threshold drug concentrations, we also observed increases of Iks activity in both SAN and ventricular cells. The NE-10064-induced enhancement of Iks was more pronounced at voltages near the Iks activation threshold (0 mV), than at more positive voltages in both cell types. Furthermore, the agonistic effects of the drug were more prominent before steady-state effects of the compound were attained, which suggests parallel agonistic and antagonistic pathways. Our results demonstrate that Iks channels in cells of the sinoatrial node region of the ...
In this study of interactions occurring within the heart, isolated superfused strips of rabbit atria, containing the sinoatrial (s.a.) node, were subjected to sinusoidal subthreshold current pulses of varied frequencies and intensities. A.C. current
TY - JOUR. T1 - Impact of manipulation of energy substrates on sinus nodal rhythm. AU - Maruyama, Hiroko. AU - Ito, Masanori. AU - Goda, Nobuhito. AU - Adachi-Akahane, Satomi. PY - 2014/1. Y1 - 2014/1. N2 - Background: The high energy demand of the heart is supported by metabolic flexibility in the utilization of energy substrates for adenosine triphosphate (ATP) synthesis. To investigate the roles of glucose and long-chain fatty acids (FA) as energy substrates in sinus nodal rhythm, we developed an isolated mouse atrial preparation and studied the effects of manipulating these energy substrates on atrial beating rate. Methods: The spontaneous beating rate of isolated atria from mouse was measured at resting tension in a modified Tyrode solution that was gassed with 100% O2 at 37°C and contained 1 of the following sets of energy substrates: 10 mM glucose plus 0.4 mM palmitate (control), 5 mM glucose plus 0.4 mM palmitate (low glucose), or 10 mM glucose without palmitate (FA (-)). Atria were ...
© 2016 CCAL. Small animal species (e.g. mouse) have a faster heart rate than large animal species (e.g. human). We have looked for the reason from the functional level to the gene level in the human, rabbit, rat and mouse using a metaanalysis approach. For example, review of the literature shows that, in isolated sinus node cells, the spontaneous rate is 4.6× faster and the action potential is 2.4 × shorter in mouse than in human. Although data on ionic currents are limited, data suggests that the density of the funny current (If) is ∼5× higher in mouse than in human, (Q10 of 1.38 was used to correct temperature differences among studies). Data on ion channel mRNA expression (qPCR) in the sinus node for the four species were collected from different research groups. To compare data, we either normalised to the Nav1.5 mRNA level (in atrial muscle) or the Cav1.2 mRNA level (in sinus node). Although different housekeeper genes were used (18S, 28S, HPRT), comparison of different data sets on the
0:06Skip to 0 minutes and 6 secondsWere going to look at the function of the heart. The main function of the heart is to supply blood to the tissues of the body, delivering oxygen and nutrients to them. Now, the heart is able to function because it is able to generate its own electrical activity. And this starts in the region known as the pacemaker, or the sinoatrial node, that is located in the right atrium. The electrical activity begins in the sinoatrial node, then spreads across the rest of the atrium, through to the other atrium, and then down into the ventricles. This causes the atria to contract before the ventricles.. 0:49Skip to 0 minutes and 49 secondsNow, the electrical activity of the heart can be measured using the electrocardiogram, or the ECG, that can measure the electrical activity of the heart, and this is depicted by letters of the alphabet P, QRS, and T. Now when the electrical activity of the heart passes through the atria, this causes the atria to contract and, as a result ...
Results of the present study suggest that the neural sympathetic discharge activity (MSNA) was markedly higher in subjects with active UC than in healthy controls. In addition, heart rate, LFRR normalized units, and LF-to-HF ratio were greater and HFRR was lower in patients, suggesting a shift of the sympathovagal modulation of the sinoatrial node toward a sympathetic predominance and parasympathetic reduction, compared with controls. As to this latter aspect, it must be pointed out that power spectrum analysis of R-R interval variability does not provide a direct measure of the neural autonomic activity directed to the heart, but, rather, it furnishes a broad noninvasive marker of the relationship between neural modulation and target organ, i.e., the sinoatrial node responsiveness (25, 29, 38).. In patients, despite the elevated values of MSNA, plasma norepinephrine was only slightly higher than in controls. It should be recalled that plasma norepinephrine levels provide imprecise estimate of ...
Sinus node dysfunction (SND), also known as sick sinus syndrome (SSS), is a group of abnormal heart rhythms caused by malfunction of the sinoatrial node, the hearts primary pacemaker.[1] Early on symptoms may be few.[1] As the disease progresses syncope may occur.[1] Other symptoms may include lightheadedness, palpitations, or chest pain.[1] The heart may beat insufficiently fast during exercise.[1] Complications may include atrial fibrillation.[2] It involves a slow heart rate with or without periods of a faster heart rate.[1] The slow heart rate may be a sinus bradycardia, sinus pause, or sinoatrial exit block.[1] When periods of a fast heart rate is present it is known as tachy-brady syndrome.[1] The underlying mechanism may include fibrosis, ion channel dysfunction, or remodeling of the sinoatrial node.[1] Other factors that can worsen the condition include medications such as beta blockers or calcium channel blockers, electrolyte abnormalities, low oxygen, and low thyroid.[1] Diagnosis is ...
TY - JOUR. T1 - Na(+)‐Ca2+ exchange current in latent pacemaker cells isolated from cat right atrium.. AU - Zhou, Z.. AU - Lipsius, S. L.. N1 - Copyright: Copyright 2016 Elsevier B.V., All rights reserved.. PY - 1993/7/1. Y1 - 1993/7/1. N2 - 1. Single latent pacemaker cells were isolated from cat right atrium, and studied in a whole‐cell configuration using a nystatin‐perforated patch recording method. The nystatin method avoids alterations in intracellular Ca2+, cellular constituents and run‐down of ionic currents. 2. Depolarizing voltage clamp pulses from ‐40 mV elicited L‐type Ca2+ current (ICa) that exhibited an initial rapid phase of inactivation followed by a secondary slower inward current component that decayed over about 100 ms. The secondary inward component appeared as a slowly decaying inward tail current following short (10‐40 ms) depolarizing clamp steps. 3. Slowly decaying inward currents were abolished by internally dialysing pacemaker cells with 2 mM EGTA using a ...
Heart failure (HF) frequently coexists with atrial fibrillation (AF) and dysfunction of the sinoatrial node (SAN), the natural pacemaker. HF is associated with chronic adrenergic stimulation, neurohormonal activation, abnormal intracellular calcium handling, elevated cardiac filling pressure and atrial stretch, and fibrosis. Pulmonary veins (PVs), which are the points of onset of ectopic electrical activity, are the most crucial AF triggers. A crosstalk between the SAN and PVs determines PV arrhythmogenesis. HF has different effects on SAN and PV electrophysiological characteristics, which critically modulate the development of AF and sick sinus syndrome. This review provides updates to improve our current understanding of the effects of HF in the electrical activity of the SAN and PVs as well as therapeutic implications for AF.
Sinus Node Dysfunction - Etiology, pathophysiology, symptoms, signs, diagnosis & prognosis from the Merck Manuals - Medical Professional Version.
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The sinoatrial node (SA Node, or SAN), also called the sinus node, is the initiator of electrical impulses within the heart, triggering the heart to beat, or contract, by firing off electrical surges. Sick sinus syndrome (SSS) is a disorder of the hearts electrical impulse formation within the sinus node.
The sinoatrial node (SA Node, or SAN), also called the sinus node, is the initiator of electrical impulses within the heart, triggering the hearts contractions by firing off electrical surges. One of the disorders that can affect the hearts electrical impulse formation within the sinus node is called sick sinus syndrome (SSS).
TY - BOOK. T1 - Multilevel determinants of foreign direct investment entry mode strategies and subsidiary survival of multinationals in China: an analysis of Nordic firms.. AU - Wang, Yi. PY - 2014. Y1 - 2014. M3 - Ph.D. thesis. BT - Multilevel determinants of foreign direct investment entry mode strategies and subsidiary survival of multinationals in China: an analysis of Nordic firms.. PB - Vaasan yliopisto. ER - ...
Innoval Döhler, based in Mexico City, will become a 100% Döhler subsidiary in January 2014 and thus will be fully integrated into the globally active Döhler group. Headquartered in Darmstadt, Germany, Döhler is a leading manufacturer of technology-based natural ingredients, ingredient systems and integrated solutions for the food and beverage industry. The Mexican ingredient specialist Innovación Alimentaria was founded in 1992 by Gustavo León. Döhler acquired close to 40% of the company back in 2006. Managed jointly by Innovación Alimentarias founder and Döhler, the company has since developed into Döhlers most important hub in Central America under its new name, Innoval Döhler. Doehler Mexico S.A. de C.V., as the 100% Döhler subsidiary will now be called, will also be increasingly active in the United States and Canada markets. An additional expertise of Doehler Mexico is the development of tailored sweetening systems and innovative low-calorie food and beverage ...
IFM Therapeutics LLC is launching its second subsidiary in less than a year. This morning, the Boston-based company, launched IFM Due (pronounced du-way), a subsidiary company developing a suite of cGAS inhibitors and STING antagonists that can target diseases like NASH, lupus and Parkinsons.
ALAMEDA, Calif.---- BioTime, Inc. and its subsidiary OrthoCyte Corporation today announced the appointment of Francois Binette, PhD, as OrthoCyte s Vice President of Research and Business Development. OrthoCyte is a wholly owned subsidiary of BioTime, Inc. that develops cellular therapeutics for orthopedic repair, diseases, and injuries.
LifeMap Sciences, a Subsidiary of BioTime, Signs Definitive Distribution Agreement with ProSpec-Tany TechnoGene ALAMEDA, Calif.--(BUSINESS WIRE)-- LifeMap Sciences, Inc. a subsidiary of
Acetylcholine, acetyl-β-methylcholine and carbamylcholine inhibited sinoatrial pacemaker activity in atria isolated from chick embryos on the 6th, 12th and 18th incubation days. Cardioinhibition persisted throughout the 5-minute exposure to cholinergic agonists in sinoatrial preparations from the 12th and l8th incubation days whereas automaticity recovered completely within 1 to 2 minutes in preparations from the 6th incubation day. Neither hydrolysis by acetylcholinesterase nor release of catecholamines from cardiac stores accounted adequately for the brevity of pacemaker inhibition by choline esters on the 6th incubation day. Evidence suggested that desensitization, most prominently observed with carbamylcholine, restricted the duration of cholinergic inhibition of the pacemaker on the 6th incubation day. Although automaticity recovered completely within 2 minutes after initial application of acetylcholine and carbamylcholine, pacemaker cells were not inhibited by a second application until ...
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Conduction System. Development of the conduction system. Cardiomyocytes form the conduction system of the heart. Molecular genetic studies have revealed the requirement of a functional network of transcription factors to determine whether a myocardial precursor cell turns into either a working cell or a cell belonging to the conduction system. Contrary to previous assumptions, the conduction system itself has no neural crest influence during development. The innervation of the conduction system in adults though is ensured through cardiac ganglia originating from the neural crest. In embryos, the innervation of this system is still missing.. Cells located in the caudal heart tube, derived from the common cardinal vein or right sinus venosus in the sinoatrial region, differentiate to form the sinoatrial node near the left venous valve. This node acts as a pacemaking component of the cardiac conduction pathway. During early development, the entire sinus venosus has a pacemaker activity. In fact, ...
The molecular mechanisms underlying atrial fibrillation, the most common sustained cardiac arrhythmia, remain poorly understood. Genome-wide association studies uncovered a major atrial fibrillation susceptibility locus on human chromosome 4q25 in close proximity to the paired-like homeodomain trans …
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The values of membrane action potentials and maximum depolarization rates of single muscle fibers in normal Tyrode solution and in low sodium solutions containing as little as 20 per cent of the sodium chloride were measured with intracellular microelectrodes. Under these conditions the membrane potential remains unchanged up to 36 per cent of [Na+]out concentration, whereas the overshoot of the action potential varies linearly with the logarithm of the external sodium concentration. The maximum depolarization rate is a linear function of the external sodium concentration. The results obtained support the ionic theory for sodium and the independence principle for sodium current related to the external sodium concentration.. ...
Abstract:. Each heartbeat is initiated by cyclic spontaneous depolarization of cardiomyocytes in the sinus node forming the primary natural pacemaker. In patients with end-stage renal disease undergoing hemodialysis, it was recently shown that the heart rate drops to very low values before they suffer from sudden cardiac death with an unexplained high incidence. We hypothesize that the electrolyte changes commonly occurring in these patients affect sinus node beating rate and could be responsible for severe bradycardia. To test this hypothesis, we extended the Fabbri et al. computational model of human sinus node cells to account for the dynamic intracellular balance of ion concentrations. Using this model, we systematically tested the effect of altered extracellular potassium, calcium, and sodium concentrations. Although sodium changes had negligible (0.15 bpm/mM) and potassium changes mild effects (8 bpm/mM), calcium changes markedly affected the beating rate (46 bpm/mM ionized calcium without ...
Email. ELMONT, N.Y. - Kentucky Derby and Preakness winner Funny Cide got down to serious business Friday at Belmont Park when he had his first work since Aug. 19. Under exercise rider Robin Smullen, Funny Cide covered a half-mile in 48.26 seconds, breezing, over the main track, which was listed as fast. The early fractions on Funny Cides work, according to the clockers, were 12.60 for the first furlong and 24.40 for the opening quarter-mile. Funny Cide galloped out five furlongs in 1:01.30. Unlike in some of his works before the Belmont Stakes that took place when the track opened at 5:30 a.m., Funny Cide was one of the first workers when the track reopened after the renovation break at 8:45. Barclay Tagg, Funny Cides trainer, said he was happy with the work because Funny Cide was relaxed. During the Triple Crown, the New York-bred Funny Cide was headstrong in many of his breezes. Weve been galloping him in draw reins to relax him, Tagg said. We spend all our time trying to keep him ...
Video articles in JoVE about natriuretic peptides include High Efficiency Differentiation of Human Pluripotent Stem Cells to Cardiomyocytes and Characterization by Flow Cytometry, Methods for the Isolation, Culture, and Functional Characterization of Sinoatrial Node Myocytes from Adult Mice, Assessing Endothelial Vasodilator Function with the Endo-PAT 2000, Semi-automated Biopanning of Bacterial Display Libraries for Peptide Affinity Reagent Discovery and Analysis of Resulting Isolates, Development of a Backbone Cyclic Peptide Library as Potential Antiparasitic Therapeutics Using Microwave Irradiation, Distinguishing Allosteric Effects from Orthosteric Binding in Protein-Ligand Interactions, Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy, Combining Chemical Cross-linking and Mass Spectrometry of Intact Protein Complexes to Study the Architecture of Multi-subunit Protein Assemblies, Microwave-assisted Functionalization
Learn and reinforce your understanding of Action potentials in pacemaker cells through video. The action potentials of the heart are usually initiated in the cells of the sinoatrial node
In this report, we demonstrated that loss of function mutations in Popdc1 and Popdc2 genes in mice are associated with stress-induced SND, resulting in chronotropic incompetence and long sinus pauses. The Popdc genes displayed overlapping myocardial expression patterns and similar biochemical properties, and the cardiac phenotypes of the null mutants were nearly identical. Our data suggest that Popdc proteins represent a novel class of cAMP binding proteins that interact with TREK-1 channels and may be involved in channel trafficking. Age-dependent decline in cardiac pacemaking in Popdc null mutants. Both mouse mutants developed SND at advanced age. Assuming that Popdc genes act in the same pathway, loss of a single gene might not have a significant impact on function in the young, since both Popdc genes might be able to substitute for each other. Obviously, the compensation became less efficient when the null mutants aged, possibly due to an age-dependent decline of Popdc expression. ...
Common Abnormal Heart RhythmsAtrial fibrillation, irregular contraction of atria. … Atrial tachycardia, a fast heart rate that starts in the atriums.Premature atrial contractions, early extra heart beats that start in ventricles.Sinus node disease or dysfunction, abnormal heart rhythms by malfunction of the hearts primary pacemaker, sinus node.More items… ...
Ablation is a procedure to treat atrial fibrillation. It uses small burns or freezes to cause some scarring on the inside of the heart to help break up the electrical signals that cause irregular heartbeats. This can help the heart maintain a normal heart rhythm.. The heart has 4 chambers. There are 2 upper chambers called atria and 2 lower chambers called ventricles. Normally, a special group of cells begin the signal to start your heartbeat. These cells are in the sinoatrial (SA) node in the upper right atrium of the heart. During atrial fibrillation, the signal to start the heartbeat doesnt begin in the sinoatrial node the way it should. Instead, the signal is sidetracked and begins somewhere else in the atria, triggering a small region at a time. The atria cant contract normally to move blood to the ventricles. This causes the atria to quiver or fibrillate. The disorganized signal spreads to the ventricles, causing them to contract irregularly and sometimes more quickly than they ...
Royal Holdings Inc. (Royal), a holding company of Arsenal Capital Partners (Arsenal), announced that it has through its Royal Packaging Specialties subsidiary, acquired the stock of Adhesives Packaging Specialties Inc. (APS) Based
Strategy is to Screen and Qualify Viable Applicants/Patients for Treatment in DR Through Regenerative BioScience, Inc.. Treatments Have Already Commenced. SARASOTA, Fla., May 5, 2014 (GLOBE NEWSWIRE) -- Caribbean International Holdings (Pink Sheets:CIHN) through its subsidiary, Regenerative BioScience, Inc., (RBS) previously announced on May 2, 2014, that it had appointed Dr. Leonel Liriano as its Medical Director, today announced, in a further development, that via the Companys new website (http://www.regenerativebioscience.com/index.html) is now fully operational and it has begun processing initial requests for its no-cost cost complimentary consultations regarding the applicants suitability to qualify for Companys revolutionary stem cell procedures.. Adult stem cells work as the repairmen of the body by replenishing and regenerating damaged tissues and cells. Certain conditions have shown marked improvement when treated with adult stem cells taken from the patients own body. ...
ADVANCED SUBSIDIARY GCE CHEMISTRY A Atoms, Bonds and Groups F321 *F * Candidates answer on the question paper. OCR supplied materials: Data Sheet for Chemistry A (inserted) Other materials required:
Scilex Holding Company, a Subsidiary of Sorrento Therapeutics, Announces Continuous Sales Growth in ZTlido® and Expects to Complete Enrollment on its SP-102 (SEMDEXA™) Phase 3 Pivotal Trial Program in 2020 - read this article along with other careers information, tips and advice on BioSpace
TAMPA, FL / ACCESSWIRE / July 24, 2019 / Advanzeon Solutions, Inc. (OTC PINK: CHCR) (Advanzeon) announced today the extension of its wholly-owned Subsidiarys (collectively, the
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FORT WORTH, TX--(Marketwired - Nov 2, 2017) - AppYea Inc. (OTC PINK: APYP) announced today that its subsidiary The Diagnostic Centers has signed its first new client, Pacific Pain & Regenerative Medicine, with locations in Los Angeles and Irvine, California and has started shipping PGx samples for testing. Under this new...
Hewlett-Packard announced that it will convert its Mechanical Design Division into a subsidiary company, CoCreate, focusing on software for mechanical design and product-data management. CoCreate will market globally under its own brand and identity, and is scheduled to start operations in November.
View complete news release for Amarantus+Subsidiary+MANF+Therapeutics+Announces+Publication+in+Science+Magazine+of+Positive+Animal+Data+for+MANF+in+Treatment+of+Retinal+Damage+and+Issuance+of+Retinal+Patent+in+Japan+Covering+MANF+and+CDNF - OTCMarkets.com
alphadogg is one of several readers to note the opening of the Mozilla Foundations new subsidiary, Mozilla Messaging, charged with developing the free, open source Thunderbird email software. Mozilla Messaging will initially focus on Thunderbird 3, which aims at improving several aspects of the sof...
Waterfront Shipping (Vancouver, BC), the marine transportation subsidiary of Methanex, said on Monday that it has reached an agreement with Mitsui O.S.K. Lines (MOL; Tokyo), Westfal-Larsen & Co. (WL;...
TechAccel LLC, the private technology and equity development company in agriculture and animal health, today announced its subsidiary RNAissance Ag LL
Wyeth Pharmaceuticals LLC, a Subsidiary of Pfizer Inc.: TYGACIL is a tetracycline class antibacterial indicated in patients 18 years of age and older for:...
PLANTATION, Florida, April 12, 2017 /PRNewswire/ -- CD International Enterprises Launches Newly Formed Subsidiary and Online Store to Distribute...
KATY, TX / ACCESSWIRE / September 24, 2020 / Neutra Corporation (OTC PINK:NTRR) subsidiary VIVIS will be entering two new lines of business - equipment leasing and CBD production consulting - in a move intended to generate additional revenue streams.
Rayner announced its investment into the US market with the establishment of a dedicated subsidiary, Rayner Surgical Inc. Based out of New York, Rayner Surgical will provide US specific marketing, reg…
Vancouver, BC, December 16, 2016 - Novelion Therapeutics (NASDAQ: NVLN) (TSX: NVLN), today announced that subsidiary Aegerion Pharmaceuticals completed the first commercial shipment of JUXTAPID® (lomitapide) to a patient in Japan. In September 2016, JUXTAPID was approved by Japans Ministry of Health, Labor & Welfare (MHLW) for patients with homozygous familial hypercholesterolemia (HoFH).
The right vagus branch innervates the sinoatrial node. In healthy people, parasympathetic tone from these sources are well- ... When hyperstimulated, the left vagal branch predisposes the heart to conduction block at the atrioventricular node. At this ...
Wahl-Schott C, Fenske S, Biel M (Apr 2014). "HCN channels: new roles in sinoatrial node function". Current Opinion in ... HCN1 channel expression is found in the sinoatrial node, the neocortex, hippocampus, cerebellar cortex, dorsal root ganglion, ...
In a healthy sinoatrial node (SAN, a complex tissue within the right atrium containing pacemaker cells that normally determine ... In the pacemaking cells of the heart (e.g., the sinoatrial node), the pacemaker potential (also called the pacemaker current) ... ISBN 978-0-07-366175-9. Verkerk AO, van Ginneken AC, Wilders R (January 2009). "Pacemaker activity of the human sinoatrial node ... SA node → ,block, atrial foci → junctional foci → ventricular foci The other foci will not see the SA node firing; however, ...
Hund, TJ; Mohler, PJ (2008). "Ankyrin-based targeting pathway regulates human sinoatrial node automaticity". Channels (Austin, ... Robaei, D; Ford, T; Ooi, SY (February 2015). "Ankyrin-B syndrome: a case of sinus node dysfunction, atrial fibrillation and ... Glukhov, AV; Fedorov, VV; Anderson, ME; Mohler, PJ; Efimov, IR (August 2010). "Functional anatomy of the murine sinus node: ... ANK2 mutations have also been identified in patients with sinus node dysfunction. Mechanistic studies on effects of these ...
It is measured using an electrocardiogram (ECG). Normally, this begins at the sinoatrial node (SA node); from here the wave of ... Pre-excitation refers to early activation of the ventricles due to impulses bypassing the AV node via an accessory pathway. ...
In the sinoatrial node, this phase is also due to the closure of the L-type calcium channels, preventing inward flux of Ca2+ ... In healthy hearts, these cells are found in the right atrium and are called the sinoatrial node (SAN; see below for more ... Joung B, Chen PS, Lin SF (March 2011). "The role of the calcium and the voltage clocks in sinoatrial node dysfunction". Yonsei ... In pacemaker cells (e.g. sinoatrial node cells), however, the increase in membrane voltage is mainly due to activation of L- ...
Larsson HP (Sep 2010). "How is the heart rate regulated in the sinoatrial node? Another piece to the puzzle". The Journal of ... "Phosphorylation and modulation of hyperpolarization-activated HCN4 channels by protein kinase A in the mouse sinoatrial node". ... Nof E, Antzelevitch C, Glikson M (Jan 2010). "The Contribution of HCN4 to normal sinus node function in humans and animal ... "Pacemaker channel dysfunction in a patient with sinus node disease". The Journal of Clinical Investigation. 111 (10): 1537-45. ...
Pacemaker cells develop in the primitive atrium and the sinus venosus to form the sinoatrial node and the atrioventricular node ... SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells ... The normal resting heart rate is based on the at-rest firing rate of the heart's sinoatrial node, where the faster pacemaker ... The heart rate is rhythmically generated by the sinoatrial node. It is also influenced by central factors through sympathetic ...
Increases heart rate in sinoatrial node (SA node) (chronotropic effect). Increases atrial cardiac muscle contractility. ( ...
At the upper end of sulcus terminalis lies sinoatrial node. Sinoatrial node receives blood supply from a branch of the right ... they end up in a brachiocephalic node. Standring 2016, pp. 997-998. Anderson et al. 2013, pp. 14-15. Cook, Wilcox & Anderson ...
The significance of this in the sinoatrial node (and, as backup, in the atrioventricular node) is that as the heart resets, or ... ISBN 978-0-12-065310-2. Larsson, H. P. (2010). "How is the heart rate regulated in the sinoatrial node? Another piece to the ...
HCN4 is the main isoform expressed in the sinoatrial node, but low levels of HCN1 and HCN2 have also been reported. The current ... Larsson, H. P. (2010). "How is the heart rate regulated in the sinoatrial node? Another piece to the puzzle". The Journal of ...
In short, they generate action potentials, but at a slower rate than the sinoatrial node. This capability is normally ... The electrical origin of atrial Purkinje fibers arrives from the sinoatrial node. Given no aberrant channels, the Purkinje ... They are influenced by electrical discharge from the sinoatrial node. During the ventricular contraction portion of the cardiac ... The Purkinje fibers do not have any known role in setting heart rate unless the SA node is compromised (when they can act as ...
"The Anatomy and Physiology of the Sinoatrial Node-A Contemporary Review". Pacing and Clinical Electrophysiology. 33 (11): 1392- ...
It causes tachycardia by blocking vagal effects on the sinoatrial node. Acetylcholine hyperpolarizes the sinoatrial node, which ... In the atrioventricular node, the resting potential is abbreviated, which facilitates conduction. This is seen as a shortened ...
In contrast, expression is low in the sinoatrial node and atrioventricular node. Within the heart, a transmural expression ...
Pacemaker cells develop in the primitive atrium and the sinus venosus to form the sinoatrial node and the atrioventricular node ... These cells form an ovoid sinoatrial node (SAN), on the left venous valve. After the development of the SAN, the superior ... the sinoatrial node and the coronary sinus. The central part of cardiogenic area is in front of the oropharyngeal membrane and ... But this pacemaker activity is actually made by a group of cells that derive from the sinoatrial right venous sinus. ...
Caution is recommended when using ticagrelor in patients with advanced sinoatrial node disease. Allergic skin reactions such as ...
Normal sinus rhythm is established by the sinoatrial (SA) node, the heart's pacemaker. The SA node is a specialized grouping of ... Without the SA node, the AV node would generate a heart rate of 40-60 beats per minute. If the AV node were blocked, the ... the sinoatrial node, the atrioventricular node, the bundle of His (atrioventricular bundle), the bundle branches, and the ... that lead directly from the SA node to the next node in the conduction system, the atrioventricular node. The impulse takes ...
"On the ionic mechanism of cyproheptadine-induced bradycardia in a rabbit sinoatrial node preparation". European Journal of ... sinoatrial automaticity (level of sinoatrial self-activation). Takahara A, Uneyama H, Sasaki N, Ueda H, Dohmoto H, Shoji M, ... and conductance through the atrioventricular node. In addition AH-1058 has been shown to decrease systolic blood pressure while ...
The sinoatrial node (S-A Node) is the heart's natural pacemaker, issuing electrical signaling that travels through the heart ... These electrical pathways contain the sinoatrial node, the atrioventricular node, and the Purkinje fibers. (Exceptions such as ... Systole of the heart is initiated by electrically excitable cells situated in the sinoatrial node. These cells are activated ... competes with the sinoatrial node for electrical control of the atrial chambers and thereby diminishes the performance of the ...
2007). "Tbx3 controls the sinoatrial node gene program and imposes pacemaker function on the atria". Genes & Development. 21 (9 ... However, in the instance of either a malfunctioning SA node or an ectopic focus bearing an intrinsic rate superior to SA node ... which can cause the rate of impulse to slow SA node blockage so that impulses never leave the atria AV node blockage (3rd ... the SA node usually suppresses the ectopic pacemaker activity due to the higher impulse rate of the SA node. ...
The cardiac pacemaker cells of the sinoatrial node in the heart provide a good example. Although such pacemaker potentials have ... The cardiac cells of the sinoatrial node provide the pacemaker potential that synchronizes the heart. The action potentials of ... Instead, the ionic current from an action potential at one node of Ranvier provokes another action potential at the next node; ... this apparent "hopping" of the action potential from node to node is known as saltatory conduction. Although the mechanism of ...
... the sinoatrial node (SA node) produces an electrical signal to control the heart rate. The signal travels from the SA node to ... The electrical signal then travels to the AV node located on the lower portion of the interatrial septum. At the AV node there ... The heart rate produced by the ventricles is much slower than that produced by the SA node. Some AV blocks are benign, or ... Mobitz I is characterized by a progressive, yet, reversible block of the AV node. On ECG, this is defined by a progressive ...
Under normal conditions, the heart's sinoatrial node determines the rate by which the organ beats - in other words, it is the ... Retrograde P waves refers to the depolarization from the AV node back towards the SA node. Accelerated junctional rhythm is ... the sinoatrial node does not control the heart's rhythm - this can happen in the case of a block in conduction somewhere along ... The electrical activity of sinus rhythm originates in the sinoatrial node and depolarizes the atria. Current then passes from ...
"Congenital deafness and sinoatrial node dysfunction in mice lacking class D L-type Ca2+ channels". Cell. 102 (1): 89-97. doi: ...
In the human heart, the sinoatrial node is located at the top of the right atrium. The sinoatrial node is the first area of the ... the sinoatrial node and the atrioventricular node). This most commonly occurs in the setting of a sinus bradycardia. ... Sinoatrial depolarization and subsequent propagation of the electrical impulse suppress the action of the lower natural ...
Atrioventricular node Bachmann's bundle Bundle branches Bundle of Kent Purkinje Fibers Sinoatrial node Logan, Carolynn M.; Rice ... As part of the electrical conduction system of the heart, it transmits the electrical impulses from the atrioventricular node ( ... as it transmits impulses from the atrioventricular node, located at the anterior-inferior end of the interatrial septum, to the ...
A wave of excitation spreads out from the sinoatrial node through the atria along specialized conduction channels. This ... The AV node is quite compact (~1 x 3 x 5 mm). The AV node lies at the lower back section of the interatrial septum near the ... The atrioventricular node or AV node is a part of the electrical conduction system of the heart that coordinates the top of the ... The AV node's normal intrinsic firing rate without stimulation (such as that from the SA node) is 40-60 times/minute. This ...
... right 426.6 Sinoatrial heart block 426.7 Atrioventricular excitation, anomalous Wolff-Parkinson-White syndrome 427 Cardiac ... Acute febrile mucocutaneous lymph node syndrome 446.5 Giant Cell arteritis(Temporal Arteritis) 447 Other disorders of arteries ...
... and the sinoatrial node, via the vagus nerve Chemically and mechanically sensitive neurons of the general visceral afferent ...
... called the sinoatrial node (SA node), is responsible for atrial propagation of this potential. The sinoatrial node (SA node) is ... Sinoatrial Node (SA Node)". StatPearls. PMID 29083608. Retrieved 10 May 2020. Cite journal requires ,journal= (help) Neil A. ... Because the sinoatrial node is responsible for the rest of the heart's electrical activity, it is sometimes called the primary ... In most humans, the concentration of pacemaker cells in the sinoatrial (SA) node is the natural pacemaker, and the resultant ...
... which run from the sinoatrial node to the atrioventricular node, converging in the region near the coronary sinus. Atrial ... The normal cardiac rhythm originates in the sinoatrial node, which is located in the right atrium near the superior vena cava. ... Because it originates close to the sinoatrial node and consists of long parallel fibers, Bachmann's bundle is, during sinus ... Bundle of His James, Thomas N. (1 October 1963). "The connecting pathways between the sinus node and A-V node and between the ...
AVRT may involve orthodromic conduction (where the impulse travels down the AV node to the ventricles and back up to the atria ... Presented order of most to least common, they are: Narrow complex Sinus tachycardia, which originates from the sino-atrial (SA ... node, near the base of the superior vena cava Atrial fibrillation Atrial flutter AV nodal reentrant tachycardia Accessory ... which the impulse travels down the accessory pathway and back up to the atria through the AV node). Orthodromic conduction ...
... is an atrial arrhythmia that occurs when the natural cardiac pacemaker site shifts between the sinoatrial node (SA node), the ... atria, and/or the atrioventricular node (AV node). This shifting of the pacemaker from the SA node to adjacent tissues is ...
... when the impulse from the sinoatrial node, the normal cardiac pacemaker, does not reach the heart chambers). As a reaction to ...
... typically from the sinoatrial or SA node) following down the bundle of HIS and ultimately stimulating the ventricles to ...
2003). "The mouse sino-atrial node expresses both the type 2 and type 3 Ca(2+) release channels/ryanodine receptors". FEBS Lett ...
This condition, called tachycardia-bradycardia syndrome, is usually caused by sinoatrial node dysfunction or block or ... Sick sinus syndrome, a sinus node dysfunction, causing alternating bradycardia and tachycardia. Often there is a long pause ( ...
It occurs when the rate of depolarization of the sinoatrial node falls below the rate of the atrioventricular node. This ... It is a protective mechanism for the heart, to compensate for the SA node no longer handling the pacemaking activity, and is ... dysrhythmia also may occur when the electrical impulses from the SA node fail to reach the AV node because of SA or AV block. ... A junctional escape complex is a normal response that may result from excessive vagal tone on the SA node (e.g. digoxin ...
... short ciliary nerves shoulder shoulder blade shin sight sigmoid colon sigmoid sinus Simian crease simian shelf sinoatrial node ... hypothalmotegmental axon hypothenar muscles ileal vessels ileocecal valve ileocolic artery ileum iliac crest iliac lymph nodes ... enlargement lumbar spine lumbar vertebrae lumbosacral enlargement lumbosacral plexus lumbrical lunate lung lymph lymph nodes ... neuromuscular junction neuron neuropil nevus nictitating membrane nigrostriatal axon nipple Nissl body nociception nodes of ...
... is a medical condition in which the nerve impulse generated in the sinoatrial node (SA node) in the atrium of the heart can not ... This type of device typically listens for a pulse from the SA node via lead in the right atrium and sends a pulse via a lead to ... Atropine works by reducing vagal stimulation through the AV node but will not be effective in those who have had a previous ... Since this accessory pacemaker also activates independently of the impulse generated at the SA node, two independent rhythms ...
The M2 muscarinic receptors decrease the heart rate by inhibiting depolarization of the sinoatrial node via Gi protein-coupled ... AV node). However, M2 receptors have no effect on the contractile forces of the ventricular muscle. Stimuli causing reflex ... reduce the contractile forces of the atrial cardiac muscle and reduce the conduction velocity of the atrioventricular node ( ...
... is a medical condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical ... If a pacemaker other than the sinoatrial node is pacing the heart, this condition is known as an escape rhythm. If no other ... as a brief period of irregular length with no electrical activity before either the sinoatrial node resumes normal pacing, or ... not sinus node (normal P morphology is lost). Junctional escape (rate 40-60): originates near the AV node; a normal P wave is ...
In AF, the normal regular electrical impulses generated by the sinoatrial node are overwhelmed by disorganized electrical waves ... Fibrosis is not limited to the muscle mass of the atria and may occur in the sinus node (SA node) and atrioventricular node (AV ... the sinoatrial node) to spread to and stimulate the muscular layer of the heart (myocardium) in both the atria and the ... Rate control is achieved with medications that work by increasing the degree of the block at the level of the AV node, ...
This is important in the aforementioned depolarization events in the pace-making activity of the sinoatrial (SA) Node in the ... T-type calcium channels function to control the pace-making activity of the SA Node within the heart and relay rapid action ... its ability to generate potentials that allow for rhythmic bursts of action potentials in cardiac cells of the sinoatrial node ... These channels allow for continuous rhythmic bursts that control the SA Node of the heart. Pharmacological evidence of T-type ...
... since the sinoatrial node (SAN) is discharging at an abnormally fast rate. Atrial ectopic tachycardia, in which the focus or ... Junctional ectopic tachycardia, in which the focus is in the atrioventricular node (AVN), and Accelerated idioventricular ...
He is also famous for discovering the sinoatrial node, the component of the heart which makes it beat, with his student Martin ... Silverman, M. E; Hollman, A. (1 October 2007). "Discovery of the sinus node by Keith and Flack: on the centennial of their 1907 ...
or Miss Sinoatrial node San people, indigenous people of southern Africa Standard algebraic notation, in chess Senior Advocate ...
... of which increased stimulation leads to decreased output of the sinoatrial node. This reflex is especially sensitive in ...
... is an elevated sinus rhythm characterized by an increase in the rate of electrical impulses arising from the sinoatrial node. ... Patients who are unresponsive to such treatment can undergo catheter ablation to potentially repair the sinus node. Sinus ... ISBN 978-0-7216-8677-6. Choudhury SR, Sharma A, Kohli V (February 2005). "Inappropriate sinus node tachycardia following ...
The electrical activity spontaneously generated by the sinoatrial node sets the pace for the rest of the heart. In absence of ... The vagus nerve acts on the sinoatrial node, slowing its conduction and modulating vagal tone, via the neurotransmitter ... the main pacemaker is a collection of cells on the border of the atria and vena cava called the sinoatrial node. Heart cells ... external stimuli, sinoatrial pacing generally maintains the heart rate in the range of 60-100 beats per minute (bpm). The two ...
... due to slowing of the sinoatrial node, and a slowing of conduction through the atrioventricular node - increasing the time ... With SA node or AV conduction disturbances, the use of diltiazem should be avoided in patients with SA or AV nodal ... Diltiazem is relatively contraindicated in the presence of sick sinus syndrome, atrioventricular node conduction disturbances, ... increasing blood flow and variably decreasing the heart rate via strong depression of A-V node conduction. It binds to the ...
The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of cells located in the wall of the ... although in some cases there have been either 2 or 3 sinoatrial node arteries supplying the SA node. Also, the SA node artery ... The sinoatrial node receives its blood supply from the sinoatrial nodal artery. This blood supply, however, can differ hugely ... "Human Sinoatrial Node Structure: 3D Microanatomy of Sinoatrial Conduction Pathways". Progress in Biophysics and Molecular ...
... or sinuatrial nodal artery or sinoatrial artery) is an artery of the heart which supplies the sinoatrial node, the natural ... The sinoatrial node surrounds the sinoatrial artery, which can run centrally (in 70% of individuals) or off-center within the ... The origin of the sinoatrial node artery is not related to coronary artery dominance, which means the side (right or left) that ... July 2008). "Anatomical Aspects of the Arterial Blood Supply to the Sinoatrial and Atrioventricular Nodes of the Human Heart". ...
... right 426.6 Sinoatrial heart block 426.7 Atrioventricular excitation, anomalous Wolff-Parkinson-White syndrome 427 Cardiac ... Acute febrile mucocutaneous lymph node syndrome 446.5 Giant Cell arteritis(Temporal Arteritis) 447 Other disorders of arteries ...
Stem Cell-Derived Nodal-Like Cardiomyocytes as a Novel Pharmacologic Tool: Insights from Sinoatrial Node Development and ... Stem Cell-Derived Nodal-Like Cardiomyocytes as a Novel Pharmacologic Tool: Insights from Sinoatrial Node Development and ... markers that might be appropriate based on the current knowledge of the gene program leading to sinoatrial node development, ... what functional characteristics might be expected and desired based on studies of the sinoatrial node, and recent efforts at ...
Regulation of L-type calcium channel activity by P21 activated kinase-1 in guinea-pig sino-atrial node pacemaker cells ... Regulation of L-type calcium channel activity by P21 activated kinase-1 in guinea-pig sino-atrial node pacemaker cells ...
Electrical activity in the heart is regulated by the hearts natural pacemaker called the sinoatrial node. Abnormalities in ...
Sick sinus syndrome is group of rhythm disturbances of the heart (arrhythmias) related to sino-atrial node dysfunction, more ...
Sick sinus syndrome is group of rhythm disturbances of the heart (arrhythmias) related to sino-atrial node dysfunction, more ...
... node. The resulting arrhythmias cause the heart to beat too fast, too slow, or irregularly. Many people who develop sick sinus ... Sinoatrial Node The sinoatrial, sinus, or SA node keeps the heart beating regularly. It is located in the wall of the right ... node. Doctors may also call this condition sinus node dysfunction or sinus node disease. The resulting arrhythmias cause the ... The AV node sits between the atria and the ventricles. Ablation destroys the tissue around the node, which prevents tachycardic ...
In a normal heart, electrical signals that cause the heart to beat begin in the area known as the sinoatrial (SA) node, located ... The electrical signal goes from the SA node down to the atrioventricular (AV) node which is between the atria and the lower ... In WPW, the electrical signals travel along an extra, abnormal pathway that goes around the AV node. This causes the signals to ... chambers of the heart (the ventricles). The AV node slows down the electrical impulse so that the ventricles have time to fill ...
... specifically from the sinoatrial node (or SA node), a small group of cells in the wall of the hearts right atrium.. The SA ... When the SA node malfunctions, autorhythmic cells in other parts of the heart take over the role of pacemaker. The result is an ... The SA Node: Where Heartbeats Come From. The beats of the heart are autorhythmic. That means the heart produces pulses through ... As noted earlier, the SA node is the hearts primary pacemaker, as it excites autorhythmic cells at the fastest rate. With ...
... especially sinoatrial node. We also summarize the current information about human SHOX2. This review article provides a new ... is crucial in the formation and differentiation of the sinoatrial node (SAN). Shox2 drives embryonic development processes and ...
The pumping of the heart is regulated by electrical current that originates in the right atrium at the sinoatrial node and then ... travels to both the left atrium and the atrioventricular node which coordinates the pumping of the ventricles. This is called ...
In AF, the normal electrical impulses that are generated by the sinoatrial node are overwhelmed by disorganized electrical ...
... and MATLAB scripts for studying the dual effects of SCZ-related genes on layer 5 pyramidal cell firing and sinoatrial node cell ...
... and MATLAB scripts for studying the dual effects of SCZ-related genes on layer 5 pyramidal cell firing and sinoatrial node cell ...
... and MATLAB scripts for studying the dual effects of SCZ-related genes on layer 5 pyramidal cell firing and sinoatrial node cell ...
The PR interval represents the time needed for an electrical impulse from the sinoatrial (SA) node to conduct through the atria ... The extra beat or ectopic beat can be from the SA node or from a secondary pacemaker. In the first case, subsequent beats are ... Atrial fibrillation occurs when the electrical impulses from the SA node are overwhelmed by disorganized impulses that ... AV node, and a special network of heart muscle cells for transmitting the electrical impulses (bundle of His, bundle branches, ...
Activation of f-channels by cAMP analogues in macropatches from rabbit sino-atrial node myocytes. J Physiol. 1997 Jun 15;501 ( ... Two distinct pathways of muscarinic current responses in rabbit sino-atrial node myocytes. Pflugers Arch. 1998 Dec;437(1):164-7 ... by cAMP gating and phosphatase inhibition in rabbit sino-atrial node myocytes. J Physiol. 1997 May 1;500 ( Pt 3):643-51.. ... Action of internal pronase on the f-channel kinetics in the rabbit SA node. J Physiol. 1999 Nov 1;520 Pt 3:737-44.. Barbuti A, ...
Sinoatrial node problems. *Damage to or infection of the heart tissue (either from aging or another heart condition) ...
Areas of expertise: Cardiac ageing; arrhythmias; cardiovascular responses to exercise; the sinoatrial node; control of heart ... study of heterogeneity continued into my early postdoctoral work where I then looked at the function of the sinoatrial node, ...
However, it is still not known if atrial and sinoatrial node cells are also involved. In this article we will first briefly ... The results provide new evidence that TRPC3 may play a role in sinoatrial and atrial arrhythmias that are caused by GPCRs ... Clinical studies have shown that AF is frequently associated with dysfunction in the sino-atrial node (SAN). The association ... homeostasis changes in sinoatrial complex being linked to TRPC3. ... However, it is still not known if atrial and sinoatrial node ...
Its also called the sinoatrial node (SA node). The sinus node is a small mass of special tissue in the right upper chamber of ... The signal travels to the AV node (atrioventricular node). This node is located between the atria and the ventricles. In the AV ... just like the sinus node. An abnormal heartbeat (arrhythmia) may occur when: * The hearts natural pacemaker (the sinus node) ... The original electrical impulse travels from the sinus node across the cells of your hearts right and left atria. ...
An electrical signal starts in the sinus node of the heart. This is also called the sinoatrial node (SA node). This is a small ... The electrical signal then travels from the sinus node to the atrioventricular node (AV node). There, the signals slow down for ... The sinus node creates an electrical signal 60 to 100 times per minute. The 2 upper chambers of the heart (atria) are ...
Regulated by the autonomic nervous system through cardiac sinoatrial node. *Parasympathetic stimulation will decrease heart ...
We crushed the sinoatrial node to reduce the heart rate. The baseline activation appeared to have endocardial origins with a ... We crushed the sinoatrial node to reduce the heart rate. The baseline activation appeared to have endocardial origins with a ... We crushed the sinoatrial node to reduce the heart rate. The baseline activation appeared to have endocardial origins with a ... We crushed the sinoatrial node to reduce the heart rate. The baseline activation appeared to have endocardial origins with a ...
Subsequently, the bodys natural pacemaker in the sinoatrial node of the heart is able to re-establish normal sinus rhythm. ...
Firing by the sinoatrial node that occurs because of overly rapid firing by the node. Or suspect you re having a heart rate or ... That occurs because of overly rapid firing by the sinoatrial node by sinoatrial. A word and generally describes location and ... Sinus tachycardia: Fast heartbeat (tachycardia) that occurs because of overly rapid firing by the sinoatrial node. It also can ... That occurs because of overly rapid firing by the sinoatrial node tachyarrhythmia definition is - arrhythmia by. Also called ...
Atrioventricular Node (D001283), Bundle of His (D002036), Heart Conduction System (D006329), Sinoatrial Node (D012849) ... Labeled items include: the Sinoatrial (SA) Node, or pacemaker of the heart; the Atrioventricular (AV) node; and the ... bundle of his, cardiac conduction system, cardio, cardiovascular system, heart, heart beat, heartbeat, sinoatrial sa node ...
The sinoatrial node (SAN) is the normal pacemaker of the mammalian heart. Over several decades, a large amount of data on the ... We constructed a comprehensive mathematical model of the spontaneous electrical activity of a human sinoatrial node (SAN) ... You are here: Home / Exposures / Computational analysis of the human sinus node action potential: model development and effects ... Changes in pacing rate upon the implementation of mutations associated with sinus node dysfunction agree with the clinical ...
Cells within the sinoatrial node, the hearts pacemaker, initiate each normal heartbeat. In pacemaker cells from the sinoatrial ... The sinoatrial node (SAN) is the primary heart pacemaker which controls heart rate and rhythm. Normal automaticity of SAN ... and isolated sinoatrial node), and by using nonlinear techniques to quantify HRV of adult and aged mice, a better understanding ... parasympathetic and sympathetic nerve neurotransmitters that bind to pacemaker cell receptors within the sinoatrial node tissue ...
  • How does the heart form a new pacemaker when the sino-atrial node is damaged? (thenakedscientists.com)
  • Cholinergic inhibition of slow delayed-rectifier K+ current in guinea pig sino-atrial node is not mediated by muscarinic receptors. (aspetjournals.org)
  • We studied the effects of cholinergic agonists on slow delayed-rectifier K+ current (IKs) in isolated cells from the sino-atrial node (SAN) region of guinea pig heart, using patch-clamp procedures. (aspetjournals.org)
  • Ionic currents responsible for the generation of pace‐maker current in the rabbit sino‐atrial node. (elsevier.com)
  • The ionic nature of the pace‐maker current (delta Ip, If, Ih) was investigated in rabbit sino‐atrial node using a single sucrose‐gap voltage‐clamp technique. (elsevier.com)
  • Electrophysiological features of murine sino-atrial node in relation to the role of i(Na). (ox.ac.uk)
  • Functional roles of ionic currents in a membrane delimited sino-atrial node (SAN) cell model were investigated. (ox.ac.uk)
  • Raised extracellular potassium attenuates the sympathetic modulation of sino-atrial node pacemaking in the isolated guinea-pig atria. (ox.ac.uk)
  • Since changes in [K(+)](o) modulate membrane currents involved in sino-atrial node pacemaking, in particular the voltage-sensitive hyperpolarization-activated current (I(f)), we investigated whether raised [K(+)](o) (from 4 mM to 8 or 12 mM) could directly affect the heart rate response to cardiac sympathetic nerve stimulation (SNS). (ox.ac.uk)
  • It is more developed that pacemaker activity of the sino-atrial node (SAN) initiates the heartbeat. (bx-795.com)
  • sino-atrial node (SAN). (bx-795.com)
  • IP3 has been implicated in acute modulation of Ca2+ in cardiac atrial1 and sino-atrial node (SAN)2, whilst atrial IP3R expression is increased in both human3 and dog models4 of atrial fibrillation. (physoc.org)
  • The present study aimed to investigate the molecular mechanisms involved in pacing function improvements of damaged sinoatrial node cells and the consequent treatment effects on sick sinus syndrome (SSS) after the use of Yiqi Tongyang. (hindawi.com)
  • The main role of a sinoatrial node cell is to initiate action potentials of the heart that can pass through cardiac muscle cells and cause contraction. (wikipedia.org)
  • however, they do so at a slower rate and therefore, if the SA node is functioning properly, its action potentials usually override those that would be produced by other tissues. (wikipedia.org)
  • Although all of the hearts cells possess the ability to generate the electrical impulses (or action potentials) which trigger cardiac contraction, the sinoatrial node is what normally initiates it, simply because it generates impulses slightly faster than the other areas with pacemaker potential . (academickids.com)
  • Cells in the SA node will naturally discharge (create action potentials) at about 70-80 times/minute. (academickids.com)
  • The spontaneous rhythmic action potentials generated by the sinoatrial node (SAN), the primary pacemaker in the heart, dictate the regular and optimal cardiac contractions that pump blood around the body. (sciencemag.org)
  • The role of Ca 2+ release channels in the sarcoplasmic reticulum in modulating physiological automaticity of the sinoatrial (SA) node was studied by recording transmembrane action potentials and membrane ionic currents in small preparations of the rabbit SA node. (fujita-hu.ac.jp)
  • Organisation of the mouse sinoatrial node: structure and expression of HCN channels. (semanticscholar.org)
  • A rapidly activating delayed rectifier K+ current regulates pacemaker activity in adult mouse sinoatrial node cells. (semanticscholar.org)
  • Ca v 1.3 voltage-gated L-type calcium channels (LTCCs) translate sound-induced depolarization into neurotransmitter release in auditory hair cells and control diastolic depolarization in the mouse sinoatrial node (SAN). (nature.com)
  • Distribution and functional role of inositol 1,4,5-trisphosphate receptors in mouse sinoatrial node. (ox.ac.uk)
  • In anesthetized rabbits (n=9), acetylcholine (ACh) was measured at the right atrium near the sinoatrial node by a cardiac microdialysis technique, and the ACh release in response to electrical stimulation of the cervical preganglionic vagal nerves was examined. (elsevier.com)
  • Objective To investigate the effects of remifentanil on sinoatrial (SA) node autorhythmicity in rabbits . (bvsalud.org)
  • Heart failure (HF) frequently coexists with atrial fibrillation (AF) and dysfunction of the sinoatrial node (SAN), the natural pacemaker. (mdpi.com)
  • Available at: https://www.heart.org/en/health-topics/atrial-fibrillation. (epnet.com)
  • Pulmonary veins (PVs) and the sinoatrial node (SAN) are crucial for genesis of atrial fibrillation. (elsevier.com)
  • Background-We hypothesized that unresponsiveness of superior sinoatrial node (SAN) to sympathetic stimulation is strongly associated with the development of symptomatic bradycardia in patients with atrial fibrillation (AF). (elsevier.com)
  • We describe a human channelopathy (termed SANDD syndrome, sinoatrial node dysfunction and deafness) with a cardiac and auditory phenotype that closely resembles that of Cacna1d −/− mice. (nature.com)
  • Sinoatrial node dysfunction and deafness is a rare genetic disease characterized by congenital severe to profound deafness with no evidence of vestibular dysfunction, associated with sinoatrial node dysfunction with pronounced bradycardia and increased variability of heart rate at rest and episodic syncopes that may be triggered by enhanced physical activity and stress. (mendelian.co)
  • The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of cells located in the wall of the right atrium of the heart. (wikipedia.org)
  • The cells of the SA node are spread out within a mesh of connective tissue, containing nerves, blood vessels, collagen and fat. (wikipedia.org)
  • Immediately surrounding the SA node cells are paranodal cells. (wikipedia.org)
  • These cells have structures intermediate between that of the SA node cells and the rest of the atrium. (wikipedia.org)
  • The connective tissue, along with the paranodal cells, insulate the SA node from the rest of the atrium, preventing the electrical activity of the atrial cells from affecting the SA node cells. (wikipedia.org)
  • The SA node cells are smaller and paler than the surrounding atrial cells, with the average cell being around 8 micrometers in diameter and 20-30 micrometers in length (1 micrometer= 0.000001 meter). (wikipedia.org)
  • Unlike the atrial cells, SA node cells contain fewer mitochondria and myofibers, as well as a smaller sarcoplasmic reticulum. (wikipedia.org)
  • This means that the SA node cells are less equipped to contract compared to the atrial and ventricular cells. (wikipedia.org)
  • This is again important in insulating the SA node from the surrounding atrial cells. (wikipedia.org)
  • The calcium and calmodulin-dependent protein kinase II (CaMKII) is present in sinoatrial node (SAN) pacemaker cells and is required for physiological "fight or flight" SAN beating rate responses. (frontiersin.org)
  • After ischemia-reperfusion injury (model group), the HCN4 protein and the optical density (OD) of the phosphorylated HCN4 protein as well as intracellular PKA activity in the sinoatrial node cells decreased significantly. (hindawi.com)
  • These findings demonstrated that the use of the traditional Chinese medicine Yiqi Tongyang could increase HCN4 protein expression and phosphorylation as well as PKA activity within sinoatrial node cells damaged by ischemia-reperfusion. (hindawi.com)
  • Action potential firing recorded from isolated sinoatrial node cells (SANCs) was reduced by 55 ± 15% and 28 ± 9% by application of PAX (3 μM) and iberiotoxin (230 nM), respectively. (nih.gov)
  • The sinoatrial node (SA node) is a bundle of nerve cells that function as a natural pacemaker for the heart . (justanswer.com)
  • When the SA node does not work correctly, other cells in the heart try to mimic its function to keep the heart beating. (justanswer.com)
  • Nicardipine-sensitive Na+-mediated single channel currents in guinea-pig sinoatrial node pacemaker cells. (biomedsearch.com)
  • 1. The Na+-dependent inward currents underlying slow diastolic depolarization of sinoatrial (SA) node cells were examined. (biomedsearch.com)
  • 2. The recording of ist was infrequent, was observed only in spontaneously beating SA node cells, and was facilitated by adding Bay-K 8644 to the pipette solution. (biomedsearch.com)
  • Heart rate (HR) regulation by the autonomic nervous system is integrated by specialized autorhythmic (pacemaker) cells located within the sinoatrial node (SAN). (ahajournals.org)
  • It has now become clear, however, that the heart rate and HRV are also determined by intrinsic properties of the pacemaker cells that comprise sinoatrial node, and that these properties respond to autonomic receptor stimulation in a non-linear mode. (omicsonline.org)
  • That HRV is determined by both the intrinsic properties of pacemaker cells in the sinoatrial node and the competing influences of the two branches of the autonomic neural input to the cells requires an expansion of our perspective about mechanisms that govern HRV in the normal heart, and how HRV changes with aging in health and in heart diseases. (omicsonline.org)
  • Explanted Shox2 + cells from the embryonic PV myocardium exhibited pacemaker characteristics including node-like electrophysiological properties and the capability to pace surrounding Shox2 − cells. (biologists.org)
  • Explain the mollecular biology of sinoatrial cells and how these features are related to its pacemaking function. (brainscape.com)
  • Because cardiac myocytes , like all nerve cells , have refractory periods following contraction during which additional contractions cannot be triggered, their pacemaker potential is overridden by the sinoatrial node. (academickids.com)
  • The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. (academickids.com)
  • If the SA node doesn't function, or the impulse generated in the SA node is blocked before it travels down the electrical conduction system, a group of cells further down the heart will become the heart's pacemaker. (academickids.com)
  • These cells form the atrioventricular node (AV node), which is an area between the atria and ventricles, within the atrial septum. (academickids.com)
  • If not, death of the affected cells will stop the SA node from triggering the heartbeat. (academickids.com)
  • The SA node is a group of specialized cells in the top of the right atrium which produces the electrical impulses that travel down to eventually reach the ventricular muscle, causing the heart to contract. (metaglossary.com)
  • sin'-o-A-tree-awl nod) ( SA node) A cluster of specialized cardiac muscle cells in the wall of the right atrium that initiate each cardiac cycle. (metaglossary.com)
  • The normal "pacemaker" for the heart is an area of specialized cells in the atrium called the sinoatrial or "SA" node. (metaglossary.com)
  • Cardiac pacemaker cells of the sinoatrial node initiate and maintain the rhythmic beating of the heart. (grantome.com)
  • Understanding of how native pacemaker cells establish proper connectivity to the remainder of the heart, however, will provide critical insight for future pharmacological and cellular based therapies aimed at correcting sinoatrial node dysfunction and/or arrhythmic disorders. (grantome.com)
  • Therefore, this five year career development program is designed to serve two principle purposes: 1) to determine the cellular and molecular mechanisms that regulate sinoatrial node patterning during development, with emphasis on how pacemaker cells become electrogenically insulated, and 2) to provided support and training for the principle investigator, Dr. Michael Bressan, as he transitions from a postdoctoral fellow to an independent researcher. (grantome.com)
  • Specifically, this proposal will test the hypothesis that shortly after pacemaker cell differentiation in the embryo, a TGFb/BMP mediated fibrotic program initiates at the sinoatrial node periphery, which in turn insulates and protects central pacemaking cells from atrial myocytes. (grantome.com)
  • This proposal, therefore, seeks to determine the largely unknown cellular and molecular mechanism that regulate developmental sinoatrial node patterning, specifically focusing on how pacemaker cells become insulated from adjacent myocardium. (grantome.com)
  • In the present study, in mouse SA node pacemaker cells, we investigated Na+ currents under physiological conditions and the expression of cardiac and neuronal Na+ channel isoforms. (ox.ac.uk)
  • Nanomolar concentrations (10 or 100 nm) of TTX, which block TTX-sensitive iNa, slowed pacemaking in both intact SA node preparations and isolated SA node cells without a significant effect on SA node conduction. (ox.ac.uk)
  • The pacemaker cells are also known as the sinoatrial node. (abpischools.org.uk)
  • Immunocytochemistry and/or immunoblotting revealed abundant expression of this protein in plasma membranes of sinoatrial node and in atrial and ventricular cells. (geoscience.net)
  • Heterogeneity of 4-aminopyridine-sensitive current in rabbit sinoatrial node cells. (ox.ac.uk)
  • The electrophysiological properties of sinoatrial (SA) node pacemaker cells vary in different regions of the node. (ox.ac.uk)
  • In this study, we have investigated variation of the 4-aminopyridine (4-AP)-sensitive current as a function of the size (as measured by the cell capacitance) of SA node cells to elucidate the ionic mechanisms. (ox.ac.uk)
  • The 10 mM 4-AP-sensitive current recorded from rabbit SA node cells was composed of transient and sustained components (Itrans and Isus, respectively). (ox.ac.uk)
  • The greater density of Isus in larger cells (presumably from the periphery) can explain the shorter action potential in the periphery of the SA node compared with that in the center. (ox.ac.uk)
  • Characterisation of the transient outward K+ current in rabbit sinoatrial node cells. (ox.ac.uk)
  • OBJECTIVE: To (i) characterise the electrophysiological and pharmacological properties of the transient outward K+ current, I(to), (ii) determine the relationship between the density of I(to) and cell size, and (iii) determine the role of I(to) in electrical activity in rabbit sinoatrial node cells at 35 degrees C. METHODS: Rabbit sinoatrial node cells were studied using whole-cell voltage and current clamp techniques. (ox.ac.uk)
  • Block of I(to) by 4-AP affected both the action potential and pacemaker activity of sinoatrial node cells and the effects were greater in cells with a larger capacitance. (ox.ac.uk)
  • CONCLUSIONS: I(to) in sinoatrial node cells shows similar electrophysiological and pharmacological properties to I(to) in atrial and ventricular cells. (ox.ac.uk)
  • The expression of I(to) in sinoatrial node cells is heterogeneous and differs in large and small cells (likely to be from the periphery and centre of the sinoatrial node, respectively). (ox.ac.uk)
  • I(to) plays an important role in action potential configuration and pacemaker activity in sinoatrial node cells, especially in larger cells. (ox.ac.uk)
  • Using isolated human sinoatrial node cells, Tsutsui et al . (sciencemag.org)
  • These clocks were uncoupled in human sinoatrial node cells that were not beating. (sciencemag.org)
  • Understanding the mechanisms that generate pacemaking activity in human sinoatrial node cells may lead to the development of better therapies for sinus arrest, a condition that is caused by malfunction of the sinoatrial node and currently treated with a permanently implanted pacemaker. (sciencemag.org)
  • Although the heart rate of humans is substantially slower than that of smaller experimental animals, current perspectives on the biophysical mechanisms underlying the automaticity of sinoatrial nodal pacemaker cells (SANCs) have been gleaned largely from studies of animal hearts. (sciencemag.org)
  • Cells in the SA node exhibit the most rapid phase 4 depolarization and thus are the dominant pacemakers in a normal heart. (mhmedical.com)
  • Action potential profiles recorded in cells isolated from sinoatrial or atrioventricular nodal tissue compared with those of cells from atrial or ventricular myocardium. (mhmedical.com)
  • Selected contribution: axial stretch increases spontaneous pacemaker activity in rabbit isolated sinoatrial node cells. (ox.ac.uk)
  • Isolated, spontaneously beating rabbit sinoatrial node cells were subjected to longitudinal stretch, using carbon fibers attached to both ends of the cell. (ox.ac.uk)
  • These observations suggest, that, even when the function of Ca 2+ channels in the cell membrane is normally maintained, depression of Ca 2+ release channels in the sarcoplasmic reticulum would prevent sufficient elevation of the Ca 2+ concentration in SA node cells for the activation of various ionic currents, and, thus adversely affect the physiological automaticity of this primary cardiac pacemaker. (fujita-hu.ac.jp)
  • Beside the posterior nodal extension of the conduction system identified by Dobrzynski et al.10 our preparations included also the enclosed node, and a AVN sub-region defined by Boyett et al.11 that was composed by loosely-packed atrial cells. (bx-795.com)
  • Cells of the sinoatrial node are the primary pacemakers of the heart. (physiologyweb.com)
  • The contribution of inactivation of the L-type Ca 2+ current (i(Ca) to overdrive suppression was investigated in rabbit sinoatrial (SA) node cells by use of the whole cell patch-clamp technique. (fujita-hu.ac.jp)
  • The accelerans nerve provides sympathetic input to the heart by releasing norepinephrine onto the cells of the sinoatrial node (SA node), and the vagus nerve provides parasympathetic input to the heart by releasing acetylcholine onto sinoatrial node cells. (wikipedia.org)
  • The sinoatrial node receives its blood supply from the sinoatrial nodal artery. (wikipedia.org)
  • For example, in most humans, this is a single artery, although in some cases there have been either 2 or 3 sinoatrial node arteries supplying the SA node. (wikipedia.org)
  • Sinoatrial node artery arising from posterolateral branch of right coronary artery: definition by screening consecutive 1500 coronary angiographies/Sag koroner arter posterolateral dalindan cikan sinoatriyal nod arteri: Ardisik 1500 koroner anjiyografi taramasi ile tanimlama. (thefreelibrary.com)
  • Objective: Sinoatrial node (SAN) artery originates from proximal segment of right coronary artery (RCA) or from left circumflex artery. (thefreelibrary.com)
  • Sinoatrial node artery artery originating from posterolateral (PL) branch of RCA is very rare. (thefreelibrary.com)
  • Conclusions: Sinoatrial node artery originating from distal RCA is very rare. (thefreelibrary.com)
  • ascending atrial branch , usually (55%) arising from the anterior stem of the right coronary artery (but 35-45% arising from the circumflex branch of the left coronary artery ), which runs around the base of the superior vena cava to reach the sinuatrial node . (biology-online.org)
  • ramus nodi sinuatrialis arteriae coronaria dextra, branch to sinuatrial node , sinuatrial nodal branch of right coronary artery , sinuatrial node artery . (biology-online.org)
  • In the majority of patients, the SA node receives blood from the right coronary artery, meaning that a myocardial infarction occluding it will cause ischaemia in the SA node unless there is a sufficiently good anastomosis from the left coronary artery. (academickids.com)
  • Sinuatrial nodal artery (SAN) arose from the RCA in 70 per cent and from the circumflex artery (CX) in 30 per cent of instances. (thefreedictionary.com)
  • In this patient the arterial network did not protect the node from the ischemia caused by the obstruction of the artery of the sinoatrial node . (bvsalud.org)
  • The sinoatrial nodal artery (or sinuatrial nodal artery or sinoatrial artery) is an artery of the heart which supplies the sinoatrial node, the natural pacemaker center of the heart, and arises from the right coronary artery in around 60% of people. (wikipedia.org)
  • In about 40% of cases, the sinoatrial artery is a branch of the left circumflex coronary artery. (wikipedia.org)
  • The origin of the sinoatrial node artery is not related to coronary artery dominance, which means the side (right or left) that provides the circulation to the back of the heart. (wikipedia.org)
  • In contrast, the atrioventricular nodal branch, that is the artery that brings blood to the atrioventricular node, depends on coronary artery dominance. (wikipedia.org)
  • The sinoatrial node surrounds the sinoatrial artery, which can run centrally (in 70% of individuals) or off-center within the node. (wikipedia.org)
  • A left S-shaped sinoatrial artery, originating from the proximal left circumflex or LCx artery, has been described as a common variant in approximately 10% of human hearts. (wikipedia.org)
  • This artery is larger than normal and supplies a good part of the left atrium, but also right-sided structures like part of the sinoatrial node and the atrioventricular nodal areas. (wikipedia.org)
  • Other subsidiary pacemakers in the atrioventricular (AV) node, specialized conduction system, and muscle may initiate electrical activation if the SA node is dysfunctional or supressed. (brainscape.com)
  • Other subsidiary pacemakers in the atrioventricular (AV) node, specialized conducting system, and muscle may initiate electrical activation if the SA node is dysfunctional or suppressed. (mhmedical.com)
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  • Recent evidence indicates that the voltage (cyclic activation and deactivation of membrane ion channels) and Ca 2+ clocks (rhythmic spontaneous sarcoplasmic reticulum Ca 2+ release) jointly regulate sinoatrial node (SAN) automaticity. (elsevier.com)
  • Background: The mechanism of sinoatrial node (SAN) automaticity is traditionally attributed to membrane ion currents. (elsevier.com)
  • Heart rate is controlled by the opposing activities of sympathetic and parasympathetic inputs to pacemaker myocytes in the sinoatrial node (SAN). (ahajournals.org)
  • The SA node is richly innervated by vagal and sympathetic fibers. (academickids.com)
  • Stimulation via sympathetic fibers causes increase in the SA node rate (thereby increasing the heart rate). (academickids.com)
  • Sympathetic activation does the opposite, causing increase sinoatrial firing and increases heart rate. (anatomyzone.com)
  • While heart rhythm is regulated entirely by the sinoatrial node under normal conditions, heart rate is regulated by sympathetic and parasympathetic input to the sinoatrial node. (wikipedia.org)
  • The cardioaccelerator center also sends additional fibers, forming the cardiac nerves via sympathetic ganglia (the cervical ganglia plus superior thoracic ganglia T1-T4) to both the SA and AV nodes, plus additional fibers to the atria and ventricles. (wikipedia.org)
  • Parasympathetic modulation of sinoatrial node pacemaker activity in rabbit heart: a unifying model, Semahat S. Demir, John W. Clark and Wayne R. Giles, 1999, American Journal of Physiology , 276, H2221-H2244. (cellml.org)
  • Parasympathetic activation decreases sinoatrial firing and thus decreases heart rate. (anatomyzone.com)
  • Selective in situ parasympathetic control of the canine sinoatrial and atrioventricular nodes. (elsevier.com)
  • When the SA node fires, the electrical impulse causes the atria to contract. (justanswer.com)
  • The same signal which makes the atria contract travels downward to the AV node, near the center of the heart. (justanswer.com)
  • The AV node sits on the right side of the wall between the left and right atria, close to the bottom of the right atrium. (justanswer.com)
  • If SA node is experimentally destroyed or stop generating impulses due to disease then the pacemaker appears in some other region of the atria especially at the junction of atria with the AV node. (thenakedscientists.com)
  • Electrical signals generated from the sinoatrial node spread across the atria to the atrioventricular node , which is located close to the opening of the coronary sinus in the right atrium. (anatomyzone.com)
  • In this study of interactions occurring within the heart, isolated superfused strips of rabbit atria, containing the sinoatrial (s.a.) node, were subjected to sinusoidal subthreshold current pulses of varied frequencies and intensities. (biomedsearch.com)
  • In a healthy heart, the SA node continuously produces action potential, setting the rhythm of the heart and so is known as the heart's natural pacemaker. (wikipedia.org)
  • The SA node is often called the natural pacemaker of the heart. (metaglossary.com)
  • The SA node is the heart's natural pacemaker. (metaglossary.com)
  • What is the definition of sinoatrial node? (webmd.com)
  • Natriuretic peptides regulate heart rate and sinoatrial node function by activating multiple natriuretic peptide receptors. (nih.gov)
  • Because rENT1-mediated transport is likely to regulate the local concentrations of adenosine in the sinoatrial node and other parts of the heart, it represents a potential pharmacological target that might be exploited to ameliorate ischemic damage during heart surgery. (geoscience.net)
  • 35): C832-C852, 1994] of the single rabbit sinoatrial node (SAN) cell so that it can simulate cellular responses to bath applications of ACh and isoprenaline as well as the effects of neuronally released ACh. (cellml.org)
  • To unravel the underlying mechanism, we incorporated the mutation-induced changes in I Na into a recently developed comprehensive computational model of a single human sinoatrial node cell (Fabbri-Severi model). (mdpi.com)
  • Here, we measured the effects of BNP and CNP on sinoatrial node (SAN) and atrial electrophysiology in isolated hearts as well as isolated SAN and right atrial myocytes from mice. (nih.gov)
  • however, recently it has been shown that TTX-sensitive (KD, 1-10 nm) neuronal Na+ channel isoforms (Nav1.1, Nav1.3 and Nav1.6) are also present and functionally important in the myocytes of the ventricles and the sinoatrial (SA) node. (ox.ac.uk)
  • 1 Great progress also has been made in defining the ionic mechanisms responsible for the sinoatrial action potential and its spontaneous pacemaker activity, including important contributory roles for I Ca,L , I k , and the funny current, I f . 1 This morphologically discrete, unifocal sinus node is not the exclusive force behind clinical sinus rhythm, however. (ahajournals.org)
  • Natriuretic peptides, including BNP and CNP, elicit their effects via two guanylyl cyclase-linked receptors denoted NPR-A and NPR-B as well as a third receptor, NPR-C. The relative contributions of these receptors to the overall effects of NPs on heart rate (HR) and sinoatrial node (SAN) function are very poorly understood. (nih.gov)
  • The sinoatrial node (SAN) is a specialized region of heart tissue present at the junction of the right atrium and superior vena cava that extends along the cristae terminalis, where it initiates each normal heart beat. (frontiersin.org)
  • However, both specialized nodes can contract like muscle tissue and produce or relay signals like nerve tissue. (justanswer.com)
  • From the capsule, thin connective tissue septa or trabeculae are extending to inside the node, dividing the later into lobes. (omicsonline.org)
  • The sinoatrial node (abbreviated SA node , also called the sinus node ) is the impulse generating (pacemaker) tissue located in the right atrium of the heart . (academickids.com)
  • We found that although the entire SAN expressed three IP(3)R mRNA isoforms, the type II IP(3)R (IP(3)R2) was the predominant protein isoform detected by Western blot using protein extracts from the SAN, atrioventricular node, and atrial tissue. (ox.ac.uk)
  • Pitx2, a target of the left-sided Nodal signaling pathway that initiates early in development, represses the sinoatrial node program and pacemaker activity on the left side. (nih.gov)
  • The healthy sinoatrial node initiates 60 to 100 beats per minute at rest. (metaglossary.com)
  • The SA node is located in the wall (myocardium) of the right atrium, laterally to the entrance of the superior vena cava in a region called the sinus venarum (hence sino- + atrial). (wikipedia.org)
  • The sinoatrial node is located lateral to the junction where the superior vena cava enters the right atrium. (anatomyzone.com)
  • In the century since the discovery by Keith and Flack of the sinoatrial node in the mole heart, a detailed mosaic of its cellular, anatomic, and electrophysiological properties has emerged. (ahajournals.org)
  • A part of the body, such as the mass of muscle fibers of the sinoatrial node, that sets the pace or rhythm of physiological activity. (thefreedictionary.com)
  • Electrical activation of the heart normally originates in the sinoatrial (SA) node, the predominant pacemaker. (brainscape.com)
  • However, in the mammalian sinoatrial node (SAN), where the heart beat originates, the expression and functional activity of IP(3)Rs have not been investigated. (ox.ac.uk)
  • Sinus node dysfunction and hyperpolarization-activated (HCN) channel subunit remodeling in a canine heart failure model. (semanticscholar.org)
  • Sinus node dysfunction following targeted disruption of the murine cardiac sodium channel gene Scn5a. (semanticscholar.org)
  • To address the mechanisms underlying this repressive activity, we hypothesized that Pitx2 regulates microRNAs (miRs) to repress the sinoatrial node genetic program. (nih.gov)
  • the sinoatrial node that regulates heartbeat. (thefreedictionary.com)
  • Sick sinus syndrome (SSS) is a group of arrhythmias induced by pacing and/or conduction dysfunction caused by lesions within the sinus sinoatrial node and surrounding tissues. (hindawi.com)
  • When the cause of the sinoatrial node dysfunction cannot be determined, medical professionals may use the term "sick sinus syndrome" (SSS). (justanswer.com)
  • The homeodomain transcription factor Shox2 controls the development and function of the native cardiac pacemaker, the sinoatrial node (SAN).Moreover, SHOX2 mutations have been associatedwith cardiac arrhythmias in humans. (kit.edu)
  • Adenosine exerts multiple receptor-mediated effects in the heart, including a negative chronotropic effect on the sinoatrial node. (geoscience.net)
  • Furthermore electrocardiogram telemetry revealed that mice with miR-17-92 cardiac-specific inactivation develop prolonged PR intervals whereas mice with miR-17-92 cardiac-specific inactivation and miR-106b-25 heterozygosity develop sinoatrial node dysfunction. (nih.gov)
  • Upregulation of the hyperpolarization-activated current increases pacemaker activity of the sinoatrial node and heart rate during pregnancy in mice. (semanticscholar.org)
  • article{Khoury2013UpregulationOT, title={Upregulation of the hyperpolarization-activated current increases pacemaker activity of the sinoatrial node and heart rate during pregnancy in mice. (semanticscholar.org)
  • Congenital deafness and sinoatrial node dysfunction in mice lacking class D L-type Ca 2+ channels. (nature.com)
  • Using immunocytochemistry and confocal microscopy, different distributions of the TTX-resistant cardiac isoform, Nav1.5, and the TTX-sensitive neuronal isoform, Nav1.1, were observed: Nav1.5 was absent from the centre of the SA node, but present in the periphery of the SA node, whereas Nav1.1 was present throughout the SA node. (ox.ac.uk)