An effect of the electrogenic sodium pump on the membrane potential in beating guinea-pig atria

1973 ◽  
Vol 344 (2) ◽  
pp. 169-180 ◽  
Author(s):  
H. G. Glitsch
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Sodium Pump ◽  
Electrogenic Sodium Pump ◽  
Guinea Pig Atria

Action of acetylcholine on the longitudinal muscle of guinea-pig ileum: the role of an electrogenic sodium pump

1973 ◽  
Vol 265 (867) ◽  
pp. 107-114 ◽  
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Sodium Pump ◽  
Longitudinal Muscle ◽  
Membrane Resistance ◽  
Free Solution ◽  
Electrogenic Sodium Pump ◽  
External Potassium ◽  
Sodium And Potassium

Intracellular recordings of membrane potential were made from the longitudinal muscle of guinea-pig terminal ileum. It was observed that ouabain or potassium-free solution depolarized the membrane. Upon readmitting potassium to potassium-free solution, the membrane potential rapidly increased. This response was blocked by ouabain and was potentiated in chloride-deficient solution, suggesting that it was due to the activity of an electrogenic sodium pump. When acetylcholine was applied, and then washed from the tissue, there followed a period of increased negativity of the membrane potential, an after-hyperpolarization. This did not occur when responses to acetylcholine were obtained in the presence of ouabain, in potassium-free solution, or in sodium-deficient solution, but the after-hyperpolarization was increased in size in chloride-deficient solution. During a 2 min application of carbachol, the membrane potential fell more rapidly in the presence of ouabain (10 -5 mol/1); this could be explained if sodium pump activity is important in retarding the decline of the sodium and potassium gradients that occurs at this time. It was concluded that the application of acetylcholine or carbachol to ileal muscle increases internal sodium and probably external potassium concentrations. These increases stimulate the activity of the electrogenic sodium pump so that, when the membrane resistance recovers, there is an increased electrogenic contribution to the membrane potential. This produces the after-hyperpolarization which is a feature of the response to acetylcholine.

Calcium channels and excitation–contraction coupling in cardiac cells. I. Two components of contraction in guinea-pig papillary muscle

1987 ◽  
Vol 65 (9) ◽  
pp. 1821-1831 ◽  
Author(s):  
E. Honoré ◽  
M. M. Adamantidis ◽  
B. A. Dupuis ◽  
C. E. Challice ◽  
P. Guilbault
Keyword(s):  
Membrane Potential ◽  
Guinea Pig ◽  
Papillary Muscle ◽  
Cardiac Cells ◽  
Resting Membrane Potential ◽  
Tonic Component ◽  
Contraction Coupling ◽  
Rich Solution ◽  
The Relationship ◽  
Guinea Pig Atria

Biphasic contractions have been obtained in guinea-pig papillary muscle by inducing partial depolarization in K+-rich solution (17 mM) containing 0.3 μM isoproterenol; whereas in guinea-pig atria, the same conditions led to monophasic contractions corresponding to the first component of contraction in papillary muscle. The relationships between the amplitude of the two components of the biphasic contraction and the resting membrane potential were sigmoidal curves. The first component of contraction was inactivated for membrane potentials less positive than those for the second component. In Na+-low solution (25 mM), biphasic contraction became monophasic subsequent to the loss of the second component, but tetraethylammonium unmasked the second component of contraction. The relationship between the amplitude of the first component of contraction and the logarithm of extracellular Ca2+ concentration was complex, whereas for the second component it was linear. When Ca2+ ions were replaced by Sr2+ ions, only the second component of contraction was observed. It is suggested that the first component of contraction may be triggered by a Ca2+ release from sarcoplasmic reticulum, induced by the fast inward Ca2+ current and (or) by the depolarization. The second component of contraction may be due to a direct activation of contractile proteins by Ca2+ entering the cell along with the slow inward Ca2+ current and diffusing through the sarcoplasm. These results do not exclude the existence of a third "tonic" component, which could possibly be mixed with the second component of contraction.

Electrogenic sodium-dependent glycine transport in sheep reticulocytes

1978 ◽  
Vol 56 (6) ◽  
pp. 545-551 ◽  
Author(s):  
Stephen Benderoff ◽  
Rose M. Johnstone ◽  
Rhoda Blostein
Keyword(s):  
Membrane Potential ◽  
Sodium Pump ◽  
Marked Decrease ◽  
Massive Bleeding ◽  
Atp Content ◽  
Chemical Gradient ◽  
Electrogenic Sodium Pump ◽  
Sodium Dependent ◽  
Glycine Transport ◽  
Measurable Change

Na+-dependent glycine transport has been studied in reticulocyte-enriched fractions of blood obtained after massive bleeding of sheep. The activity is dependent on the sodium electrochemical potential and the membrane potential. The sodium chemical gradient was varied by changing either external or internal Na+ and the membrane potential, by addition of valinomycin. Similar results were obtained with resealed reticulocyte ghosts. Under conditions optimal for sodium pumping (intracellular Na+ > 50 mM), ouabain inhibited glycine uptake prior to any measurable change in the cellular Na+ suggesting that in these cells an electrogenic sodium pump is sufficiently active to contribute to the membrane potential. Na+-dependent glycine transport undergoes a marked decrease during Song-term incubation at 37 °C. During this time, the cells maintain their integrity and ATP content but undergo maturation as evidenced in the decrease in cells with reticulocyte morphology.

Sodium-Potassium Movement and the Regulation of Cardiac Muscle Activity

1982 ◽  
Vol 37 (7-8) ◽  
pp. 679-681
Author(s):  
Jürgen Daut ◽  
Reinhardt Rüdel
Keyword(s):  
Guinea Pig ◽  
Cardiac Muscle ◽  
Muscle Activity ◽  
Cardiac Glycoside ◽  
Sodium Pump ◽  
Ventricular Muscle ◽  
Sodium Potassium ◽  
Sodium Activity ◽  
Electrogenic Sodium Pump ◽  
Fast Acting

Abstract The changes in intracellular sodium activity and contractility produced by short-lasting application of a fast-acting cardiac glycoside were measured in guinea-pig ventricular muscle. It was found that under certain conditions the change in twitch tension paralleled the change in sodium activity. It is suggested that the electrogenic sodium pump may be involved in the regulation of both the mechanical and the electrical activity of cardiac muscle.

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