Biomaterial Database

Activation of the electrogenic sodium pump in guinea-pig auricles by internal sodium ions. 1972

H G Glitsch

1. The effect of various intracellular Na concentrations ([Na](i)) on the membrane potential after hypothermia was studied in guinea-pig auricles.2. For varying [Na](i), the atria were cooled for 4 hr at 4-6 degrees C in a K-poor solution with different concentrations of NaCl. The auricles were rewarmed in normal Tyrode solution at 35 degrees C.3. Extracellular space (ECS), intracellular Na and K concentrations ([Na](i) and [K](i)) and membrane potential of the atria were measured before and after hypothermia.4. The ECS, measured as inulin space, amounted to 350 ml./kg wet wt. at 35 degrees C and to 300 ml./kg wet wt. at 4-6 degrees C.5. [K](i) decreased during cooling and increased during rewarming the auricles. [Na](i) increased during hypothermia in bathing fluids containing NaCl, but decreased in NaCl- and Na-free solutions. At the beginning of rewarming a net Na transport occurred from cells with high [Na](i), while a net Na uptake took place in atria with low [Na](i).6. At the same time, the membrane potential of auricles with increased [Na](i) hyperpolarized beyond the steady-state value recorded at the end of rewarming, or even beyond the calculated K(+) equilibrium potential (E(K)). Afterwards, the hyperpolarization levelled off, while the E(K) values increased further. The membrane potential of atria with decreased [Na](i) showed no transitory hyperpolarization during rewarming.7. The hyperpolarization beyond the steady-state value of membrane potential in rewarmed auricles was significantly correlated to the active Na efflux.8. From these results it is concluded that the membrane potential of guinea-pig atria after hypothermia is affected by an active, electrogenic Na pump activated by intracellular Na ions.

UI	MeSH Term	Description	Entries
D008564	Membrane Potentials	The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).	Resting Potentials,Transmembrane Potentials,Delta Psi,Resting Membrane Potential,Transmembrane Electrical Potential Difference,Transmembrane Potential Difference,Difference, Transmembrane Potential,Differences, Transmembrane Potential,Membrane Potential,Membrane Potential, Resting,Membrane Potentials, Resting,Potential Difference, Transmembrane,Potential Differences, Transmembrane,Potential, Membrane,Potential, Resting,Potential, Transmembrane,Potentials, Membrane,Potentials, Resting,Potentials, Transmembrane,Resting Membrane Potentials,Resting Potential,Transmembrane Potential,Transmembrane Potential Differences
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
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.
D005110	Extracellular Space	Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.	Intercellular Space,Extracellular Spaces,Intercellular Spaces,Space, Extracellular,Space, Intercellular,Spaces, Extracellular,Spaces, Intercellular
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
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D006325	Heart Atria	The chambers of the heart, to which the BLOOD returns from the circulation.	Heart Atrium,Left Atrium,Right Atrium,Atria, Heart,Atrium, Heart,Atrium, Left,Atrium, Right
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
D001693	Biological Transport, Active	The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.	Active Transport,Uphill Transport,Active Biological Transport,Biologic Transport, Active,Transport, Active Biological,Active Biologic Transport,Transport, Active,Transport, Active Biologic,Transport, Uphill
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