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Titolo:
NA- IMPLICATION FOR THE MECHANISM OF FATIGUE( AND K+ EFFECT ON CONTRACTILITY OF FROG SARTORIUS MUSCLE )
Autore:
BOUCLIN R; CHARBONNEAU E; RENAUD JM;
Indirizzi:
UNIV OTTAWA,DEPT PHYSIOL,451 SMYTH RD OTTAWA ON K1H 8M5 CANADA UNIV OTTAWA,DEPT PHYSIOL OTTAWA ON K1H 8M5 CANADA
Titolo Testata:
American journal of physiology. Cell physiology
fascicolo: 6, volume: 37, anno: 1995,
pagine: 1528 - 1536
SICI:
0363-6143(1995)37:6<1528:NIFTMO>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
SKELETAL-MUSCLE; STIMULATED CONTRACTIONS; EXCITATION-FREQUENCY; XENOPUS-LAEVIS; RANA-PIPIENS; RECOVERY; POTASSIUM; FIBERS; ACTIVATION; DEPENDENCE;
Keywords:
TWITCH; TETANUS; MEMBRANE EXCITABILITY; T TUBULE; EXCITATION-CONTRACTION COUPLING;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
33
Recensione:
Indirizzi per estratti:
Citazione:
R. Bouclin et al., "NA- IMPLICATION FOR THE MECHANISM OF FATIGUE( AND K+ EFFECT ON CONTRACTILITY OF FROG SARTORIUS MUSCLE )", American journal of physiology. Cell physiology, 37(6), 1995, pp. 1528-1536

Abstract

Although a decrease in extracellular Na+ and an increase in K+ concentration are believed to contribute to the decrease in force during fatigue, the force of unfatigued muscle decreases only with quite large changes in Na+ and K+ concentration. The objective of this study was todetermine whether concomitant and smaller changes in Na+ and K+ concentration have greater effects on muscle contractility than individual changes. At 3 mM K+, a large decrease in Na+ from 120 to 60 mM had no effect on the twitch force, while the tetanic force decreased by 31.2%. At 120 mM Na+, an increase in K+ from 3 to 9 mM potentiated the twitch force by 41.1%, had no effect on the tetanic force at 7 mM, and decreased the tetanic force by 40.4% at 9 mM; both the twitch force and tetanic force were completely abolished at 11 mM K+. The potentiation of the twitch force between 3 and 9 mM K+ was less at 60, 80, and 100 mM than at 120 mM Na+. A reduction in Na+ concentration also reduced the K+ concentration at which the twitch force and tetanic force decreased and were completely abolished. It is shown that the combined effects of Na+ and K+ on the twitch and tetanic contractions were greater than the sum of their individual effects. Furthermore, it is proposed that neither Na+ nor K+ alone can be considered as an important factor in the decrease in force during fatigue, whereas together they are important for the tetanic contraction, but not for the twitch contraction.

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Documento generato il 13/07/20 alle ore 17:22:24