Biomaterial Database

Two ouabain binding sites in guinea pig heart Na+-K+-ATPase. Differentiation by sodium and erythrosin B. 1984

U Fricke

3H-ouabain binding to guinea pig heart NaK-ATPase resulted in two different cardiac glycoside binding sites: A high affinity, low capacity binding was obtained at a KD = 2.6 X 10(-7) mol/l (about 40% of the binding sites) whereas a low affinity, high capacity binding was established at a KD = 1.3 X 10(-6) mol/l (about 60% of the binding sites). Similar results were obtained when studying the effect of increasing Na+-concentrations on ouabain binding: again two distinct processes involved in the Na+/ouabain interaction could be demonstrated. Whereas one ouabain binding process was activated at rather low Na+-concentrations (K0.5 = 4.5 mmol/l), the other ouabain binding process was predominant at high Na+-concentrations only (K0.5 = 69 mmol/l). Comparing these data with the ouabain action on contractile force and with NaK-ATPase activity in guinea pig heart, the high affinity binding of ouabain seems to correlate with the inotropic action, whereas the low affinity ouabain binding is more related to NaK-ATPase inhibition. To further discriminate the two cardiac glycoside binding sites operative in guinea pig heart muscle, erythrosin B, shown to be an inhibitor of the high affinity ouabain binding in this preparation, was applied to isolated guinea pig left atria in the presence of increasing ouabain concentrations. There was no change in the ouabain induced inotropy or toxicity by erythrosin B. These results could indicate that the low affinity ouabain binding is responsible for both inotropic and toxic actions in guinea pig heart. However, the functional significance of the high affinity ouabain binding would then remain obscure.(ABSTRACT TRUNCATED AT 250 WORDS)

UI	MeSH Term	Description	Entries
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010042	Ouabain	A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.	Acocantherin,G-Strophanthin,Acolongifloroside K,G Strophanthin
D011955	Receptors, Drug	Proteins that bind specific drugs with high affinity and trigger intracellular changes influencing the behavior of cells. Drug receptors are generally thought to be receptors for some endogenous substance not otherwise specified.	Drug Receptors,Drug Receptor,Receptor, Drug
D002301	Cardiac Glycosides	Cyclopentanophenanthrenes with a 5- or 6-membered lactone ring attached at the 17-position and SUGARS attached at the 3-position. Plants they come from have long been used in congestive heart failure. They increase the force of cardiac contraction without significantly affecting other parameters, but are very toxic at larger doses. Their mechanism of action usually involves inhibition of the NA(+)-K(+)-EXCHANGING ATPASE and they are often used in cell biological studies for that purpose.	Cardiac Glycoside,Cardiotonic Steroid,Cardiotonic Steroids,Glycoside, Cardiac,Glycosides, Cardiac,Steroid, Cardiotonic,Steroids, Cardiotonic
D004923	Erythrosine	A tetraiodofluorescein used as a red coloring in some foods (cherries, fish), as a disclosure of DENTAL PLAQUE, and as a stain of some cell types. It has structural similarity to THYROXINE.	FD & C Red No. 3,2',4',5',7'-Tetraiodofluorescein,Erythrosin,Erythrosin B,Erythrosine B,F D & C #3,FDC Red No. 3
D005452	Fluoresceins	A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.	Tetraiodofluorescein
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
D000254	Sodium-Potassium-Exchanging ATPase	An enzyme that catalyzes the active transport system of sodium and potassium ions across the cell wall. Sodium and potassium ions are closely coupled with membrane ATPase which undergoes phosphorylation and dephosphorylation, thereby providing energy for transport of these ions against concentration gradients.	ATPase, Sodium, Potassium,Adenosinetriphosphatase, Sodium, Potassium,Na(+)-K(+)-Exchanging ATPase,Na(+)-K(+)-Transporting ATPase,Potassium Pump,Sodium Pump,Sodium, Potassium ATPase,Sodium, Potassium Adenosinetriphosphatase,Sodium-Potassium Pump,Adenosine Triphosphatase, Sodium, Potassium,Na(+) K(+)-Transporting ATPase,Sodium, Potassium Adenosine Triphosphatase,ATPase Sodium, Potassium,ATPase, Sodium-Potassium-Exchanging,Adenosinetriphosphatase Sodium, Potassium,Pump, Potassium,Pump, Sodium,Pump, Sodium-Potassium,Sodium Potassium Exchanging ATPase,Sodium Potassium Pump
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