Biomaterial Database

Role of Na+/K+-ATPase in the high extracellular calcium-induced impairment of rabbit aorta contractile activity. 2004

Ana Ortega, and Amaya Aleixandre

Departamento de Farmacología, Facultad de Medicina, Universidad Complutense, 28040 Madrid, Spain.

The present study was designed to prove whether the activation of the sarcolemmal Na+/K+-ATPase in the rabbit aorta could explain the decreased contraction caused in this tissue by high extracellular calcium. To demonstrate this hypothesis, we evaluate the modification in the contractile responses to KCl and alpha1-adrenoceptor agonists (methoxamine and phenylephrine) produced by a high extracellular Ca2+ concentration (10 mM) in isolated rabbit aorta rings when the Na+/K+-ATPase is inhibited with ouabain. Ouabain 10(-4) M caused an initial rapid increase in tone in the rabbit aorta rings, which could be linked to the release of catecholamines provoked when the Na+/K+-ATPase in the nerve terminal was blocked. This glycoside also caused a delayed contractile response in the preparations that could be linked to the inhibition of the Na+/K+-ATPase in the sarcolemma of the smooth muscle. The maximum inhibition of the sarcolemmal pump was fixed 2 h and 15 min after ouabain 10(-4) M administration. Both responses were smaller with the 10-mM Ca2+ concentration than with the 2.5-mM Ca2+ concentration. The contractions elicited by KCl and the alpha1-adrenoceptor agonists were higher in the aorta ring preparations incubated with the 2.5-mM Ca2+ solution than in the aorta ring preparations incubated with the 10-mM Ca2+ solution. When the Ca2+ concentration in the organ bath was 2.5 mM, 10(-4) M ouabain administration caused a decrease in the responses to KCl and alpha1-adrenoceptor agonists. By contrast, when the Ca2+ concentration in the organ bath was 10 mM, 10(-4) M ouabain did not modify these responses. As a consequence, the contractions elicited by KCl were very similar in all the ouabain-treated preparations and those elicited by the alpha1-adrenoceptor agonists in ouabain-treated preparations were even higher when the Ca2+ concentration in the organ bath was 10 mM than when the Ca2+ concentration in the organ bath was 2.5 mM. The results of this study suggest that the increase in extracellular Ca2+ concentration may facilitate the functioning of the Na+/K+-ATPase in the vascular smooth muscle (VSM) and produces opposite effects to ouabain. This effect of high extracellular Ca2+ concentration on the sarcolemmal pump may explain the decrease in the contractile responses elicited by depolarization and alpha1-adrenoceptor stimulation observed in rabbit aorta ring preparations.

UI	MeSH Term	Description	Entries
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
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
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
D001011	Aorta	The main trunk of the systemic arteries.	Aortas
D014661	Vasoconstriction	The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.	Vasoconstrictions
D045604	Extracellular Fluid	The fluid of the body that is outside of CELLS. It is the external environment for the cells.	Interstitial Fluid,Intercellular Fluid,Extracellular Fluids,Fluid, Extracellular,Fluid, Intercellular,Fluid, Interstitial,Fluids, Extracellular,Fluids, Intercellular,Fluids, Interstitial,Intercellular Fluids,Interstitial Fluids
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