scholarly journals NapA Na+/H+Antiporter as a Sodium Extrusion System Supplementary to the Vacuolar Na+-ATPase inEnterococcus hirae

1998 ◽  
Vol 62 (12) ◽  
pp. 2371-2374 ◽  
Author(s):  
Miyuki KAWANO ◽  
Kazuei IGARASHI ◽  
Marc SOLIOZ ◽  
Yoshimi KAKINUMA
Keyword(s):  
Sodium Extrusion

The energy requirement for sodium extrusion from a frog muscle

1954 ◽  
Vol 142 (908) ◽  
pp. 383-392 ◽  
Keyword(s):  
Oxygen Consumption ◽  
Energy Production ◽  
Energy Requirement ◽  
Metabolic Inhibitors ◽  
Sodium Efflux ◽  
External Potassium ◽  
Radioactive Sodium ◽  
Sodium Extrusion ◽  
Frog Sartorius ◽  
Made In

Parallel measurements have been made of the oxygen consumption and efflux of radioactive sodium in pairs of frog sartorius muscles. Calculation of the amount of secretory work necessary for an active extrusion of sodium at the observed rate showed that it would involve the utilization of about one-tenth of the energy available from resting metabolism.This figure may reasonably be regarded as a lower limit to the efficiency of the secretory mechanism. Some of the measurements were made in a potassium-free Ringer’s solution, and others with an external potassium concentration of 10mM. In the potassium-rich medium, both the sodium efflux and the oxygen consumption were increased, the proportion of the energy production required for sodium extrusion remaining roughly constant. The action of dinitrophenol and other metabolic inhibitors on the sodium efflux in sartorius muscles was examined, but there were no very obvious effects.

Branchial effects of epinephrine in the seawater-adapted mullet. II. Na+ and Cl- extrusion

1975 ◽  
Vol 228 (2) ◽  
pp. 441-447 ◽  
Author(s):  
P Pic ◽  
N Mayer-Gostan ◽  
J Maetz
Keyword(s):  
Exchange Mechanism ◽  
Beta Blockade ◽  
Oral Ingestion ◽  
Extrusion Rate ◽  
Alpha Blockers ◽  
Adrenergic Response ◽  
Alpha Blockade ◽  
Sodium Extrusion ◽  
Leak Pathway ◽  
Rapid Transfer

Injection of epinephrine into Mugil capito adapted to seawater is followed by a 40-60% inhibition of the Na and Cl effluxes. Simultaneously the Na influx is decreased by 30%, the overall result being a reduction of the net sodium extrusion rate by the gill. The change in Na influx is in part explained by a 75-80% decrease of the oral ingestion of seawater. This branchial adrenergic response is sensitive to alpha-blockade by phentolamine and tolazoline and insensitive to beta-blockade by propranolol. Both alpha-blockers are ineffective when injected alone. Propranolol injected alone mimics epinephrine while simultaneous injection of phentolamine blocks the response to propranolol. Rapid transfer experiments suggest that epinephrine inhibits the branchial Cl pump and its associated Na/K exchange mechanism. The leak pathway for these ions remains insensitive to epinephrine.

Axonal Adaptations to Osmotic and Ionic Stress in an Invertebrate Osmoconformer (Mercierella Enigmatica Fauvel): III. Adaptations to Hyposmotic Dilution

1978 ◽  
Vol 76 (1) ◽  
pp. 221-235
Author(s):  
J. A. BENSON ◽  
J. E. TREHERNE
Keyword(s):  
Axonal Swelling ◽  
Osmotic Concentration ◽  
Bathing Medium ◽  
Axon Membrane ◽  
Ionic Stress ◽  
Sodium Inactivation ◽  
Sodium Extrusion ◽  
Potassium Gradient ◽  
Sodium And Potassium

The giant axons of this extreme osmoconformer were adapted, in vitro, to progressive hyposmotic dilution of the bathing medium (from 1024 m-Osmol to concentrations as low as 76.8 m-Osmol). Hyposmotic adaptation is associated with reductions in the intracellular concentrations of both sodium and potassium ions. These reductions do not appear to result from appreciable axonal swelling. The different electrical responses to isosmotic and hyposmotic dilution suggest that reduction in [Na+]1 results from ouabain-dependent sodium extrusion, in response to ionic dilution, and that reduction in [K+]1 is induced by a combination of ionic and osmotic dilution. The reduced level of intracellular potassium achieved during hyposmotic adaptation represents a balance between the necessity to contribute to osmotic equilibration and to maintain a potassium gradient across the axon membrane sufficient to produce appreciable axonal hyperpolarization during dilution of the bathing medium. This hyperpolarization tends to maintain the amplitude of the action potential, by compensating for reduction in overshoot (with decline in ENa), and by reducing sodium inactivation. This, together with the reduction in [Na+]1, enables overshooting action potentials of relatively large amplitude and rapid rise time to be maintained during more than tenfold dilution of the ionic and osmotic concentration of the bathing medium.

The Effect of External Potassium Ions on the Electrical Potential Measured Across the Gills of the Teleost, Dormitator Maculatus

1974 ◽  
Vol 61 (2) ◽  
pp. 277-283
Author(s):  
DAVID H. EVANS ◽  
JEFFREY C. CARRIER ◽  
MARGARET B. BOGAN
Keyword(s):  
Sea Water ◽  
Electrical Potential ◽  
Potassium Ions ◽  
Sodium Efflux ◽  
Electrical Potentials ◽  
External Potassium ◽  
Potassium Influx ◽  
Sodium Extrusion ◽  
Sufficient Magnitude ◽  
Stimulation Of

1. A technique has been developed for the measurement of electrical potentials (TGP's) across the gills of free-swimming, Dormitator maculatus. 2. Transfer of fish to various KCl solutions is correlated with changes in the TGP, which are not of sufficient magnitude to account for the known potassium stimulation of sodium efflux from this species. 3. Transfer to potassium-free sea water results in little or no change in TGP while previous results have shown that such a transfer is correlated with a 22% reduction of sodium efflux. 4. Transfer to fresh water results in a reduction of TGP from +17 mV (inside positive) to -36 mV which is sufficient to account for the instantaneous reduction in sodium efflux previously shown for this species. 5. It is concluded that while changes in TGP can account for the ‘Na-free effect’ in D. maculatus they cannot account for the potassium effects on sodium extrusion. This supports the previous conclusion that sodium efflux and potassium influx are chemically linked in this species.

Erythrocyte enzymopathies

2010 ◽  
pp. 4468-4473
Author(s):  
Ernest Beutler
Keyword(s):  
Atomic State ◽  
Red Cell ◽  
Hexose Monophosphate ◽  
Essential Proteins ◽  
Hexose Monophosphate Pathway ◽  
Sulphydryl Groups ◽  
Sodium Extrusion ◽  
2,3 Dpg

Numerous enzymes, including those of the hexose monophosphate pathway and glycolysis, are active in the red cell. They are required for the generation of ATP (needed to supply energy for sodium extrusion) and the reductants NADH and NADPH, necessary to maintain haemoglobin in its active ferrous atomic state, as well as for the integrity of sulphydryl groups present on essential proteins. 2,3-diphosphoglycerate (2,3-DPG), an intermediate of ...

scholarly journals Effect on Membrane Potential and Electrical Activity of Adding Sodium to Sodium-Depleted Cardiac Purkinje Fibers

1974 ◽  
Vol 64 (4) ◽  
pp. 473-493 ◽  
Author(s):  
Jay R. Wiggins ◽  
Paul F. Cranefield
Keyword(s):  
Membrane Potential ◽  
Electrical Activity ◽  
Resting Potential ◽  
Average Increase ◽  
Purkinje Fibers ◽  
Cardiac Purkinje Fibers ◽  
Sodium Extrusion

Canine cardiac Purkinje fibers exposed to Na-free solutions containing 128 mM TEA and 16 mM Ca show resting potentials in the range -50 to -90 mV; if the concentration of Na in the perfusate is raised from 0 to 4 to 24 mM, hyperpolarization follows. If the initial resting potential is low, the hyperpolarization tends to be greater; the average increase in the presence of 8 mM Na is 14 mV. Such hyperpolarization is not induced by adding Na to K-free solutions, is not seen in cooled fibers, or in fibers exposed to 10-3 M ouabain, nor is it induced by adding Li and thus may result from electrogenic sodium extrusion. Fibers exposed to Na-free solutions are often spontaneously active; if they are quiescent they often show repetitive activity during depolarizing pulses. Such spontaneous or repetitive activity is suppressed by the addition of Na. This suppression may or may not be related to the hyperpolarization.

scholarly journals Role of calcium in volume regulation by dog red blood cells.

1975 ◽  
Vol 65 (1) ◽  
pp. 84-96 ◽  
Author(s):  
J C Parker ◽  
H J Gitelman ◽  
P S Glosson ◽  
D L Leonard
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Sodium Concentration ◽  
Calcium Flux ◽  
Osmotic Swelling ◽  
Calcium Dependent ◽  
Sodium Extrusion ◽  
Calcium Permeability ◽  
External Calcium

Dog red blood cells (RBC) are shown to regulate their volume in anisosmotic media. Extrusion of water from osmotically swollen cells requires external calcium and is associated with net outward sodium movement. Accumulation of water by osmotically shrunken cells is not calcium dependent and is associated with net sodium uptake. Net movements of calcium are influenced by several variables including cell volume, pH, medium sodium concentration, and cellular sodium concentration. Osmotic swelling of cells increases calcium permeability, and this effect is diminished at acid pH. Net calcium flux in either direction between cells and medium is facilitated when the sodium concentrations is low in the compartment from which calcium moves and/or high in the compartment to which calcium moves. The hypothesis is advanced that energy for active sodium extrusion in dog RBC comes from passive, inward flow of calcium through a countertransport mechanism.

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