Impulse generation in supraventricular tissue is inhibited by adenosine and acetylcholine via the activation of A1 and M2 receptors coupled to inwardly rectifying GIRK/KIR3.1/3.4 channels, respectively. Unlike M2 receptors, bradycardia produced by A1 receptors activation predominates over negative inotropy. Such difference suggests that other ion currents may contribute to adenosine chronoselectivity. In isolated spontaneously beating rat atria, blockade of KCa2/SK channels with apamin and Cav1 (L-type) channels with nifedipine or verapamil, sensitized atria to the negative inotropic action of the A1 agonist, R-PIA, without affecting the nucleoside negative chronotropy. Patch-clamp experiments in the whole-cell configuration mode demonstrate that adenosine, via A1 receptors, activates the inwardly-rectifying GIRK/KIR3.1/KIR3.4 current resulting in hyperpolarization of atrial cardiomyocytes, which may slow down heart rate. Conversely, the nucleoside inactivates a small conductance Ca(2+)-activated KCa2/SK outward current, which eventually reduces the repolarizing force and thereby prolong action potentials duration and Ca(2+) influx into cardiomyocytes. Immunolocalization studies showed that differences in A1 receptors distribut...Continue Reading
Spatial distribution of connexin43, the major cardiac gap junction protein, in the developing and adult rat heart
On the mechanism of activation of muscarinic K+ channels by adenosine in isolated atrial cells: involvement of GTP-binding proteins
Potassium channel blockers differentially affect carbachol and (-)-N6-phenylisopropyladenosine on guinea-pig atria
8-Cyclopentyl-1,3-dipropylxanthine (DPCPX)--a selective high affinity antagonist radioligand for A1 adenosine receptors
Apamin as a selective blocker of the calcium-dependent potassium channel in neuroblastoma cells: voltage-clamp and biochemical characterization of the toxin receptor
Slowing of shortening velocity of rat cardiac myocytes by adenosine receptor stimulation regardless of beta-adrenergic stimulation
Potassium channel blockade of atrial negative inotropic responses to P1-purinoceptor and muscarinic receptor agonists and to cromakalim
Effects of R-PIA, a selective A1 adenosine agonist, on haemodynamics and ischaemic arrhythmias in pigs
Supersensitivity mismatch of adenosine in the transplanted human heart: chrono- and dromotropy versus inotropy
Regional differences in the response of the isolated sino-atrial node of the rabbit to vagal stimulation
Adenosine and adenosine receptors in the cardiovascular system: biochemistry, physiology, and pharmacology
Selective activation of Ca2+-activated K+ channels by co-localized Ca2+ channels in hippocampal neurons
Characterization of the murine A1 adenosine receptor promoter, potent regulation by GATA-4 and Nkx2.5.
Effects of K(+)-channel blockers on A1-adenosine receptor-mediated negative inotropy and chronotropy of guinea-pig isolated left and right atria
Overexpressed A(1) adenosine receptors reduce activation of acetylcholine-sensitive K(+) current by native muscarinic M(2) receptors in rat atrial myocytes
Expression of multiple subtypes of muscarinic receptors and cellular distribution in the human heart
Quantitation of mRNAs for M(1) to M(5) subtypes of muscarinic receptors in rat heart and brain cortex
Depletion of T-tubules and specific subcellular changes in sarcolemmal proteins in tachycardia-induced heart failure
Molecular identification and functional roles of a Ca(2+)-activated K+ channel in human and mouse hearts
Differential expression of small-conductance Ca2+-activated K+ channels SK1, SK2, and SK3 in mouse atrial and ventricular myocytes
Anti-arrhythmic drug therapy for atrial fibrillation: current anti-arrhythmic drugs, investigational agents, and innovative approaches
Ablation of a Ca2+-activated K+ channel (SK2 channel) results in action potential prolongation in atrial myocytes and atrial fibrillation
Slow infusion of calcium channel blockers compared with intravenous adenosine in the emergency treatment of supraventricular tachycardia
M3 muscarinic receptors mediate positive inotropic responses in mouse atria: a study with muscarinic receptor knockout mice
Adenosine receptors and the heart: role in regulation of coronary blood flow and cardiac electrophysiology
Galantamine inhibits slowly inactivating K+ currents with a dual dose-response relationship in differentiated N1E-115 cells and in CA1 neurones
Tertiapin-Q removes a mechanosensitive component of muscarinic control of the sinoatrial pacemaker in the rat
Loss of Ca(v)1.3 (CACNA1D) function in a human channelopathy with bradycardia and congenital deafness
Crystal structure of the mammalian GIRK2 K+ channel and gating regulation by G proteins, PIP2, and sodium
Decreased expression of small-conductance Ca2+-activated K+ channels SK1 and SK2 in human chronic atrial fibrillation
The surmountable effect of FSCPX, an irreversible A(1) adenosine receptor antagonist, on the negative inotropic action of A(1) adenosine receptor full agonists in isolated guinea pig left atria
GIRK channel activation via adenosine or muscarinic receptors has similar effects on rat atrial electrophysiology
The guinea pig atrial A1 adenosine receptor reserve for the direct negative inotropic effect of adenosine
Rolofylline, an adenosine A1 receptor antagonist, inhibits osteoclast differentiation as an inverse agonist
Selective activation of heteromeric SK channels contributes to action potential repolarization in mouse atrial myocytes
ADP-Induced Ca(2+) Signaling and Proliferation of Rat Ventricular Myofibroblasts Depend on Phospholipase C-Linked TRP Channels Activation Within Lipid Rafts
Mineralocorticoid receptor antagonists lead to increased adenosine bioavailability and modulate contractile cardiac parameters.
The Ionotropic P2X4 Receptor has Unique Properties in the Heart by Mediating the Negative Chronotropic Effect of ATP While Increasing the Ventricular Inotropy
Bradyarrhythmias are slow heart rates. Symptoms may include syncope, dizziness, fatigure, shortness of breath, and chest pains. Find the latest research on bradyarrhythmias here.
Caveolins & Signal Transduction
Caveolins are small proteins with a hairpin loop conformation that are located in the plasma membrane of various cell types where they bind cholesterol and interact with receptors essential for several signal transduction pathways. Here is the latest research.
Arrhythmias are abnormalities in heart rhythms, which can be either too fast or too slow. They can result from abnormalities of the initiation of an impulse or impulse conduction or a combination of both. Here is the latest research on arrhythmias.
Atrial fibrillation refers to the abnormal heart rhythm characterized by rapid and irregular beating of the atria. Here is the latest research.
Atrial fibrillation is a common arrhythmia that is associated with substantial morbidity and mortality, particularly due to stroke and thromboembolism. Here is the latest research.