Effects of Cardiac Glycosides on Skeletal Muscle

De-Nês, Bruna Tramontin; Greeff, K.

doi:10.1007/978-3-642-68163-9_23

Cited by 2 publications

(1 citation statement)

References 69 publications

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“…It has been known for some time that pretreatment with ouabain reduces the contractility of isolated muscles (for a review, see Dénes & Greeff 1981). A detailed study showed that in isolated rat soleus and extensor digitorum longus (EDL) muscles, ouabain induces a marked but reversible reduction in force development (Nielsen & Clausen 1996).…”

Section: Na+k+ Pump Deficiency Impairs Contractile Performance Withimentioning

confidence: 99%

The Na⁺,K⁺pump and muscle excitability

Clausen

Nielsen

Harrison

et al. 1998

Acta Physiologica Scandinavica

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In most types of mammalian skeletal muscles the total concentration of Na+,K+ pumps is 0.2-0.8 nmol g wet wt(-1). At rest, only around 5% of these Na+,K+ pumps are active, but during high-frequency stimulation, virtually all Na+,K+ pumps may be called into action within a few seconds. Despite this large capacity for active Na+,K+ transport, excitation often induces a net loss of K+, a net gain of Na+, depolarization and ensuing loss of excitability. In muscles exposed to high [K+]o or low [Na+]o, alone or combined, excitability is reduced. Under these conditions, hormonal or excitation-induced stimulation of the Na+,K+ pump leads to considerable force recovery. This recovery can be blocked by ouabain and seems to be the result of Na+,K+ pump induced hyperpolarization and restoration of Na+,K+ gradients. In muscles where the capacity of the Na+,K+ pump is reduced, the decline in the force developing during continuous electrical stimulation (30-90 Hz) is accelerated and the subsequent force recovery considerably delayed. The loss of endurance is significant within a few seconds after the onset of stimulation. Increased concentration of Na+ channels or open-time of Na+ channels is also associated with reduced endurance and impairment of force recovery. This indicates that during contractile activity, excitability is acutely dependent on the ratio between Na+ entry and Na+,K+ pump capacity. Contrary to previous assumptions, the Na+,K+ pump, due to rapid activation of its large transport capacity seems to play a dynamic role in the from second to second ongoing restoration and maintenance of excitability in working skeletal muscle.

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Section: Na+k+ Pump Deficiency Impairs Contractile Performance Withimentioning

confidence: 99%

The Na⁺,K⁺pump and muscle excitability

Clausen

Nielsen

Harrison

et al. 1998

Acta Physiologica Scandinavica

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Digoxin and Its Related Endogenous Factors

Jortani

Valdes

1997

Critical Reviews in Clinical Laboratory Sciences

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The digitalis drugs are plant-derived cardenolide compounds used medicinally for several hundred years. These drugs elicit inotropic and chronotropic effects on the heart, but they also affect many other tissues. The mechanism of action involves inhibition of the ion-transport activity of a membrane-associated protein called Na, K-ATPase (sodium pump). Present theory holds that the sodium pump is the principal molecular receptor for the digitalis drugs. Recent evidence indicates the presence of naturally occurring digitalis-like compounds in mammals. It is believed these compounds, collectively known as either digitalis-like (DLF) or ouabain-like (OLF) factors, may be endogenous hormones regulating the biological activity of the sodium pump and its isoforms. The presence of deglycosylated and other congeners of one specific DLF, the digoxin-like immunoreactive factor (DLIF), has very recently been described in humans. Digoxin as a drug is the most widely prescribed digitalis in the U.S., and its measurement in serum has established a model for present-day therapeutic drug monitoring (TDM). Historically, the accurate measurement of digoxin in blood has been difficult. This article focuses on the present understanding of the clinical use of digoxin, factors that affect the accuracy of measuring digoxin, the principle of measuring metabolically active species of digoxin, and the effects of DLIF and other interfering substances in digoxin immunoassay.

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Effects of Cardiac Glycosides on Skeletal Muscle

Cited by 2 publications

References 69 publications

The Na⁺,K⁺pump and muscle excitability

The Na⁺,K⁺pump and muscle excitability

Digoxin and Its Related Endogenous Factors

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Effects of Cardiac Glycosides on Skeletal Muscle

Cited by 2 publications

References 69 publications

The Na+,K+pump and muscle excitability

The Na+,K+pump and muscle excitability

Digoxin and Its Related Endogenous Factors

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Product

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The Na⁺,K⁺pump and muscle excitability

The Na⁺,K⁺pump and muscle excitability