Biomaterial Database

Antagonism by adenosine and ATP of an isoprenaline-induced background current in guinea-pig ventricular myocytes. 1990

A C Rankin, and R Sitsapesan, and K A Kane

University Department of Medical Cardiology, Royal Infirmary, Glasgow, UK.

A background current induced by isoprenaline, and its modulation by adenosine and ATP, have been studied using the whole cell patch clamp technique in guinea-pig ventricular myocytes. Isoprenaline (1-2000 nM) caused an inward shift of the holding current, in addition to increasing the inward calcium current (ICa). The effect on the background current was maximal earlier than the increase in ICa, but was of shorter duration. The magnitude of the background current was concentration dependent with a EC50 of 8 nM. This current was unaffected by tetrodotoxin 20 microM, Cd 200 microM or verapamil, 10 microM and potassium channel blockade (intracellular Cs, extracellular Cs 20 mM, Ba 2 mM or tetraethylammonium 10 mM). Lowering the chloride content of the electrode solution reduced the magnitude of the background current. The background current was also induced by histamine (1 or 10 microM). Adenosine (10-1000 microM) and and ATP (200 microM) antagonised the isoprenaline induced background current and the increase in ICa. The histamine effects on these currents were also reduced by adenosine. These results suggest that this background current may be carried by chloride ions and may be mediated via an increase in intracellular cyclic AMP concentration. Antagonism of this current may contribute to the antiarrhythmic actions of adenosine and ATP but their mechanisms of action are yet to be determined.

UI	MeSH Term	Description	Entries
D007545	Isoproterenol	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.	Isoprenaline,Isopropylarterenol,4-(1-Hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol,Euspiran,Isadrin,Isadrine,Isopropyl Noradrenaline,Isopropylnoradrenaline,Isopropylnorepinephrine,Isoproterenol Hydrochloride,Isoproterenol Sulfate,Isuprel,Izadrin,Norisodrine,Novodrin,Hydrochloride, Isoproterenol,Noradrenaline, Isopropyl,Sulfate, Isoproterenol
D008297	Male		Males
D008564	Membrane Potentials	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).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
D006168	Guinea Pigs	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.	Cavia,Cavia porcellus,Guinea Pig,Pig, Guinea,Pigs, Guinea
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D000241	Adenosine	A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.	Adenocard,Adenoscan
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D000889	Anti-Arrhythmia Agents	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.	Anti-Arrhythmia Agent,Anti-Arrhythmia Drug,Anti-Arrhythmic,Antiarrhythmia Agent,Antiarrhythmia Drug,Antiarrhythmic Drug,Antifibrillatory Agent,Antifibrillatory Agents,Cardiac Depressant,Cardiac Depressants,Myocardial Depressant,Myocardial Depressants,Anti-Arrhythmia Drugs,Anti-Arrhythmics,Antiarrhythmia Agents,Antiarrhythmia Drugs,Antiarrhythmic Drugs,Agent, Anti-Arrhythmia,Agent, Antiarrhythmia,Agent, Antifibrillatory,Agents, Anti-Arrhythmia,Agents, Antiarrhythmia,Agents, Antifibrillatory,Anti Arrhythmia Agent,Anti Arrhythmia Agents,Anti Arrhythmia Drug,Anti Arrhythmia Drugs,Anti Arrhythmic,Anti Arrhythmics,Depressant, Cardiac,Depressant, Myocardial,Depressants, Cardiac,Depressants, Myocardial,Drug, Anti-Arrhythmia,Drug, Antiarrhythmia,Drug, Antiarrhythmic,Drugs, Anti-Arrhythmia,Drugs, Antiarrhythmia,Drugs, Antiarrhythmic
D066298	In Vitro Techniques	Methods to study reactions or processes taking place in an artificial environment outside the living organism.	In Vitro Test,In Vitro Testing,In Vitro Tests,In Vitro as Topic,In Vitro,In Vitro Technique,In Vitro Testings,Technique, In Vitro,Techniques, In Vitro,Test, In Vitro,Testing, In Vitro,Testings, In Vitro,Tests, In Vitro,Vitro Testing, In