Ole Bækgaard Nielsen

Effects of reduced electrochemical Na+ gradient on contractility in skeletal muscle: role of the Na+-K+ pump

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Effects of reduced electrochemical Na+ gradient on contractility in skeletal muscle: role of the Na+-K+ pump. / Overgaard, Kristian; Nielsen, Ole Bækgaard; Clausen, T.

In: Pflügers Archiv - European Journal of Physiology, Vol. 434, No. 4, 1997, p. 457-65.

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@article{b75bb9e0f92d11de9c17000ea68e967b,
title = "Effects of reduced electrochemical Na+ gradient on contractility in skeletal muscle: role of the Na+-K+ pump",
abstract = "Continued excitation of skeletal muscle may induce a combination of a low extracellular Na+ concentration ([Na+]o) and a high extracellular K+ concentration ([K+]o) in the T-tubular lumen, which may contribute to fatigue. Here, we examine the role of the Na+-K+ pump in the maintenance of contractility in isolated rat soleus muscles when the Na+, K+ gradients have been altered. When [Na+]o is lowered to 25 mM by substituting Na+ with choline, tetanic force is decreased to 30% of the control level after 60 min. Subsequent stimulation of the Na+-K+ pump with insulin or catecholamines induces a decrease in [Na+]i and hyperpolarization. This is associated with a force recovery to 80-90% of the control level which can be abolished by ouabain. This force recovery depends on hyperpolarization and is correlated to the decrease in -Na+-i (r = 0. 93; P<0.001). The inhibitory effect of a low -Na+-o on force development is considerably potentiated by increasing [K+]o. Again, stimulation of the Na+-K+ pump leads to rapid force recovery. The Na+-K+ pump has a large potential for rapid compensation of the excitation-induced rundown of Na+, K+ gradients and contributes, via its electrogenic effect, to the membrane potential. We conclude that these actions of the Na+-K+ pump are essential for the maintenance of excitability and contractile force.",
keywords = "Animals, Electrochemistry, Extracellular Space, Female, Male, Membrane Potentials, Muscle Contraction, Muscle Fibers, Skeletal, Muscle, Skeletal, Osmolar Concentration, Potassium, Rats, Rats, Wistar, Sodium, Sodium-Potassium-Exchanging ATPase, Stimulation, Chemical",
author = "Kristian Overgaard and Nielsen, {Ole B{\ae}kgaard} and T Clausen",
year = "1997",
language = "English",
volume = "434",
pages = "457--65",
journal = "Pfl{\"u}gers Archiv - European Journal of Physiology",
issn = "0031-6768",
publisher = "Springer",
number = "4",

}

RIS

TY - JOUR

T1 - Effects of reduced electrochemical Na+ gradient on contractility in skeletal muscle: role of the Na+-K+ pump

AU - Overgaard, Kristian

AU - Nielsen, Ole Bækgaard

AU - Clausen, T

PY - 1997

Y1 - 1997

N2 - Continued excitation of skeletal muscle may induce a combination of a low extracellular Na+ concentration ([Na+]o) and a high extracellular K+ concentration ([K+]o) in the T-tubular lumen, which may contribute to fatigue. Here, we examine the role of the Na+-K+ pump in the maintenance of contractility in isolated rat soleus muscles when the Na+, K+ gradients have been altered. When [Na+]o is lowered to 25 mM by substituting Na+ with choline, tetanic force is decreased to 30% of the control level after 60 min. Subsequent stimulation of the Na+-K+ pump with insulin or catecholamines induces a decrease in [Na+]i and hyperpolarization. This is associated with a force recovery to 80-90% of the control level which can be abolished by ouabain. This force recovery depends on hyperpolarization and is correlated to the decrease in -Na+-i (r = 0. 93; P<0.001). The inhibitory effect of a low -Na+-o on force development is considerably potentiated by increasing [K+]o. Again, stimulation of the Na+-K+ pump leads to rapid force recovery. The Na+-K+ pump has a large potential for rapid compensation of the excitation-induced rundown of Na+, K+ gradients and contributes, via its electrogenic effect, to the membrane potential. We conclude that these actions of the Na+-K+ pump are essential for the maintenance of excitability and contractile force.

AB - Continued excitation of skeletal muscle may induce a combination of a low extracellular Na+ concentration ([Na+]o) and a high extracellular K+ concentration ([K+]o) in the T-tubular lumen, which may contribute to fatigue. Here, we examine the role of the Na+-K+ pump in the maintenance of contractility in isolated rat soleus muscles when the Na+, K+ gradients have been altered. When [Na+]o is lowered to 25 mM by substituting Na+ with choline, tetanic force is decreased to 30% of the control level after 60 min. Subsequent stimulation of the Na+-K+ pump with insulin or catecholamines induces a decrease in [Na+]i and hyperpolarization. This is associated with a force recovery to 80-90% of the control level which can be abolished by ouabain. This force recovery depends on hyperpolarization and is correlated to the decrease in -Na+-i (r = 0. 93; P<0.001). The inhibitory effect of a low -Na+-o on force development is considerably potentiated by increasing [K+]o. Again, stimulation of the Na+-K+ pump leads to rapid force recovery. The Na+-K+ pump has a large potential for rapid compensation of the excitation-induced rundown of Na+, K+ gradients and contributes, via its electrogenic effect, to the membrane potential. We conclude that these actions of the Na+-K+ pump are essential for the maintenance of excitability and contractile force.

KW - Animals

KW - Electrochemistry

KW - Extracellular Space

KW - Female

KW - Male

KW - Membrane Potentials

KW - Muscle Contraction

KW - Muscle Fibers, Skeletal

KW - Muscle, Skeletal

KW - Osmolar Concentration

KW - Potassium

KW - Rats

KW - Rats, Wistar

KW - Sodium

KW - Sodium-Potassium-Exchanging ATPase

KW - Stimulation, Chemical

M3 - Journal article

C2 - 9211813

VL - 434

SP - 457

EP - 465

JO - Pflügers Archiv - European Journal of Physiology

JF - Pflügers Archiv - European Journal of Physiology

SN - 0031-6768

IS - 4

ER -