Biomaterial Database

Ouabain-receptor interactions in (Na+ + K+)-ATPase preparations. A contribution to the problem of nonlinear Scatchard plots. 1976

E Erdmann, and G Philipp, and Tanner

Specific [3H]ouabain binding to rat and guinea pig skeletal muscle (musculus soleus) was studied using a rapid centrifugation and a filtration method. Both assays gave identical results: the incubation of the cell membranes in 50 mM imidazole/HCl buffer pH 7.25 or 7.4 MgCl2, Pi caused a time dependent loss of (Na+ +K+)-ATPase activity indicating an alteration of the membrane preparation. Ouabain binding properties were changed concomitantly. If ouabain binding was allowed to proceed until equilibrium was reached (3 min in rat and 10 min in guinea pig) at 37 degrees C the data plotted according to Scatchard followed a straight line. The dissociation constants of the ouabain-receptor-complexes of the rat cell membrane preparation as calculated from the slope of the plot (KD = 134 nM) and from the ratio of the dissociation and association rate constants (KD = 175 nM) agreed within experimental error with that determined by Clausen and Hansen [(1974) Biochim. Biophys. Acta 345, 387-404] in intact soleus muscles (KD = 210 nM). If ouabain binding was allowed to proceed for a longer period, however, nonlinear Scatchard plots resulted with an identical maximal number of binding sites but inconstant and decreased affinity for the cardiac glycoside. Experimental evidence is presented that nonlinear Scatchard plots often obtained in hormone (drug)-receptor binding experiments may (among other things) be the result of damaged cell membrane particles in vitro.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
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
D011188	Potassium	An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
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
D004789	Enzyme Activation	Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.	Activation, Enzyme,Activations, Enzyme,Enzyme Activations
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
D000251	Adenosine Triphosphatases	A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.	ATPases,Adenosinetriphosphatase,ATPase,ATPase, DNA-Dependent,Adenosine Triphosphatase,DNA-Dependent ATPase,DNA-Dependent Adenosinetriphosphatases,ATPase, DNA Dependent,Adenosinetriphosphatases, DNA-Dependent,DNA Dependent ATPase,DNA Dependent Adenosinetriphosphatases,Triphosphatase, Adenosine
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
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23