Biomaterial Database

Respective involvements of high- and low-affinity digitalis receptors in the inotropic response of isolated rat heart to ouabain. 1986

L G Lelievre, and D Charlemagne, and C Mouas, and B Swynghedauw

High- and low-affinity digitalis receptors coexist in rat cardiac sarcolemma. In this study, their relative involvement in the inotropic effect of ouabain was evaluated on an isolated Langendorff rat heart preparation working under isovolumic conditions at a low external calcium concentration (0.25 mM). This involvement was estimated according to both the development of the inotropic response to ouabain (10(-8)-10(-4)M) and the time course of the washing out of the biological effect. In each phenomenon considered, and whatever the index of inotropy chosen, the high-affinity digitalis receptor (EC50: 1-2 X 10(-8) M) contributed to 25-40% of the maximal inotropy (evoked by 10(-4) M ouabain). Low-affinity receptors (EC50: 1-2 X 10(-5) M) accounted for 60-75%. These apparent affinities were identical to those previously determined in sarcolemma isolated from rat heart perfused with 0.25 mM Ca2+. The biphasic effect of ouabain was related to both the inhibition of high- and low-sensitivity Na+, K+-ATPase forms and the corresponding number of ouabain-binding sites occupied. These results support the concept that the Na+, K+-ATPase highly sensitive to ouabain as revealed by lowering calcium is the in vivo manifestation of the high-sensitivity inotropic component.

UI	MeSH Term	Description	Entries
D008433	Mathematics	The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Mathematic
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
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
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
D001665	Binding Sites	The parts of a macromolecule that directly participate in its specific combination with another molecule.	Combining Site,Binding Site,Combining Sites,Site, Binding,Site, Combining,Sites, Binding,Sites, Combining
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus