The value of the electrocardiogram in the differential diagnosis of tachycardia with a widened QRS complex. Adenosine serves as a building block for adenosine triphosphate (ATP). For example, adenosine levels in the cortex and basal forebrain accumulate during prolonged wakefulness and fall during recovery sleep. Published by Elsevier Inc. All rights reserved. From these results, we proposed that, after stimulation of A, Because cardiac myocytes contain millimole concentrations of ATP, adenosine activation of K, Protection against infarction afforded by preconditioning is mediated by A. Under physiologic and pathophysiologic conditions, adenosine is released from cells, and it interacts with specific cell membrane receptors to modulate cell function in an autocrine or paracrine manner. If bradycardia or AV block does not respond to theophylline, adrenergic drugs, atropine, or cardiac pacing may be effective. These astrocytes will, in turn, increase their Ca2+ levels through the action of the P2Y receptor (P2YR) but do not release ATP. Demonstration of R,-type adenosine receptors in bovine myocardium by radioligand binding. Mechanism of adenosine-induced inhibition of calcium current in guinea pig ventricular cells. Administering adenosine into the lateral dorsal tegmental nucleus decreases wakefulness and increases sleep. Activities and some properties of 5′-nucleotidase, adenosine kinase and adenosine deaminase in tissues from vertebrates and invertebrates in relation to the control of the concentration and the physiological role of adenosine. The physiological activity of adenine compounds with especial reference to their action upon the mammalian heart. By activating specific adenosine receptors (A1, A2a, A2b and A3), extracellular likely reduces development of atherosclerosis and may activate cellular pathways that prevent ischemia-reperfusion injury. Metabolism of adenosine and sites of production in the heart. Inhibition by purines of the inotropic action of isoprenaline in rat atria. Structure and function of signal-transducing GTP-binding proteins. Adenosine and supraventricular tachycardia. Jacobson, Z.-G. Gao, in Encyclopedia of Neuroscience, 2009. Adenosine, a natural metabolic substance, is ubiquitous in all living cells. Intravenous adenosine in the treatment of supraventricular tachycardia: a dose-ranging study and interaction with dipyridamole. The effects of adenosine on cardiac electrophysiologic properties are consequences of complex interactions among the specific cardiac target structures, the density and type of adenosine receptors, and the effector systems. Moreover, adenosine helps to maintain tissue integrity by modulating the function of the immune system. Under physiological condition, adenosine is continuously formed in the extracellular matrix from ATP (released A comparison between adenosine receptors mediating adenylate cyclase inhibition and cardiac depression in the guinea pig heart. Indirect Adenosine Action: Cyclic AMP-Dependent Action of Adenosine.—Adenosine antagonizes the electrophysiologic and biochemical effects of β-adrenergic agonists on the heart, a situation that is related to the regulation of intracellular cyclic AMP and is observed only when the heart is pretreated with β-adrenergic agonists. Adenosine reduces caiecholamine contractile re sponses in oxygenated and hypoxic atria. The principles for the management of proarrhythmias associated with adenosine administration are outlined in Figure 9-3. The recommended dose of theophylline is 150 to 250 mg as a slow intravenous bolus injection (approximately 100 mg/minute). ADP adducts of NNK and NNAL, namely NNK(ADP)+, NNK(ADPH), and NNAL(ADP)+ have been identified in studies of NNK metabolism with rat pancreas [53], liver [53, 66] and lung microsomes [66], NNK(ADP)+ and NNAL(ADP)+ are formed with catalysis by NAD glycohydrolase, which also catalyzes similar reactions of nicotine, cotinine, and 3-acetylpyridine. Gamboa A(1), Abraham R, Diedrich A, Shibao C, Paranjape SY, Farley G, Biaggioni I. Tachyarrhythmias can be categorized as either narrow (QRS duration, less than 120 ms) or wide (QRS duration, 120 ms or more) complex tachyarrhythmias. Role of extracellular and intracellular adenosine in the attenuation of catecholamine evoked responses in guinea pig heart. Different sites of adenosine formation in the heart. Modulation of calcium channel function by phosphorylation in guinea pig ventricular cells and phospholipid bilayer membranes. Intracellular fluoride activation of muscarinic K channel in atrial cell membrane [abstract]. Image, Atrioventricular delay/block; terminates SVT and necessitates AVN as an obligatory component of the reentrant circuit, May transiently suppress junctional tachycardia, May transiently suppress automatic tachy cardia, Enhances preexcitation due to AVN blockade; may shorten anterograde refractoriness, AVRT (orthodromic reentrant tachycardia/WPW), AVRT (antidromic reentrant tachycardia/WPW). Massive release of purines, including adenosine, occurs after metabolic stress and trauma. We use cookies to help provide and enhance our service and tailor content and ads. It has been proposed that adenosine may function as a ‘retaliatory metabolite’. Rapid and safe termination of supraventricular tachycardia in children by adcnosine. Differential electrophysiologic properties of decremental retrograde pathways in long RP incelar tachycardia. H.N. There are four known types of adenosine receptors in humans: A 1, A 2A, A 2B and A 3; each is encoded by a different gene. Adenosine is the molecule that is the end product of dephosphorylation of ATP. Adenosine receptors: physiological regulation and biochemical mechanisms. Proarrhythmic responses are also common after a bolus injection of adenosine. Cardiac arrhythmias. First, we discuss adenosine metabolism and receptors in the cardiac system. A review of (1) adenosine metabolism and receptors in the cardiac system, (2) adenosine-mediated signal transduction pathways in the regulation of cellular electrophysiology in various cardiac cell types, and (3) the clinical usefulness of adenosine in cardiac electrophysiology is presented. Ulf von Euler—Norepinephrine and the Nobel Prize. In the case of wide complex tachycardia, the usefulness of adenosine for the diagnosis is less certain, mainly because of safety issues and because most wide complex tachycardias in an unselected patient population are ventricular tachycardias. Cardiac electrophysiologic effects of adenosine exemplify the critical importance of cellular mechanisms in clinical medicine. Fozzard HA Haber E Jennings RB Katz AM Morgan HE. Comparative electrophysiologic effects of adenosine triphosphate and adenosine in the canine heart: influence of atropine, propranolol, vagotomy, dipyridamole and aminophylline. Otherwise, an adenosine receptor antagonist (e.g., theophylline, aminophylline) is the initial drug of choice. Nucleoside transport in animal cells: review. Baghdoyan, in Encyclopedia of Behavioral Neuroscience, 2010.

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