Biomaterial Database

Dissociation of intracellular sodium from contractile state in guinea-pig hearts treated with ouabain. 1998

N B Radford, and J D Makos, and R Ramasamy, and A D Sherry, and C R Malloy

University of Texas Southwestern Medical Center at Dallas, USA.

The positive inotropic effect of cardiac glycosides has been attributed to inhibition of the Na-K-ATPase, accumulation of intracellular sodium and enhanced calcium availability due to Na-Ca exchange. However, few measurements of intracellular sodium in the functioning left ventricle following ouabain exposure at therapeutic doses are available. Our experimental objective was to quantitate the relationship between contractile state and intracellular sodium measured by 23Na nuclear magnetic resonance spectroscopy or atomic absorption in the intact heart. Isolated guinea-pig hearts, perfused in the Langendorff mode, were paced and then exposed to ouabain (3x10(-7)m) for 30 min. Left-ventricular pressure was monitored continuously. Intracellular sodium was measured either at 1-min intervals throughout the perfusion by shift reagent-aided 23Na nuclear magnetic resonance spectroscopy in the beating heart or following 30 minutes of perfusion by atomic absorption in myocardial tissue. While treatment with ouabain was associated with almost a two-fold rise in developed pressure, there was no significant increase in intracellular sodium measured by either technique. Thus, the positive inotropic effect of ouabain in this model is not associated with significant changes in bulk intracellular sodium. However, these results do not exclude the possibility of shifts between intracellular pools which would not be detected in bulk measurements, or changes in NMR-invisible intracellular pools which are not detectable by single quantum spectroscopy techniques.

UI	MeSH Term	Description	Entries
D007424	Intracellular Fluid	The fluid inside CELLS.	Fluid, Intracellular,Fluids, Intracellular,Intracellular Fluids
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
D010477	Perfusion	Treatment process involving the injection of fluid into an organ or tissue.	Perfusions
D004791	Enzyme Inhibitors	Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.	Enzyme Inhibitor,Inhibitor, Enzyme,Inhibitors, Enzyme
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
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