Biomaterial Database

An identification of the K activated Na pump current in sheep Purkinje fibres. 1982

H G Glitsch, and H Pusch, and T Schumacher, and F Verdonck

The cell membrane of sheep Purkinje fibers hyperpolarizes transiently on returning to K containing media after several minutes in K free solution. To analyse this 'K activated response' voltage clamp experiments and measurements of the internal Na activity (aiNa) are performed in fibres bathed in solution containing 0.2-2 mM BaCl2. Compared to the response in Tyrode solution the transient hyperpolarization beyond the resting potential is increased in Ba containing media. The response is blocked by 10(-4) M dihydroouabain. During the response, in Ba treated fibres, aiNa and a transient outward current decline with the same time constant at all clamp potentials tested. The transient outward current is most probably due to a temporary increase in electrogenic Na pumping. Both the amplitude and the time constant of the pump current show little voltage dependence. The electrogenic fraction of the active Na efflux is estimated to be about 39% and is independent of aiNa. Ba ions facilitate the analysis of the pump current in voltage clamped fibres because K depletion is reduced and changes of the I-V relationship by K depletion are minimized. It is concluded that activation of the electrogenic Na pump is mainly responsible for the K activated response of fibres in Ba containing media.

UI	MeSH Term	Description	Entries
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.
D011690	Purkinje Fibers	Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.	Purkinje Fiber,Fiber, Purkinje,Fibers, Purkinje
D006329	Heart Conduction System	An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.	Conduction System, Heart,Conduction Systems, Heart,Heart Conduction Systems,System, Heart Conduction,Systems, Heart Conduction
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
D001464	Barium	An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.
D012756	Sheep	Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS.	Ovis,Sheep, Dall,Dall Sheep,Ovis dalli
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
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