Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
ION GRADIENTS AND CONTRACTILITY IN SKELETAL-MUSCLE - THE ROLE OF ACTIVE NA+, K+ TRANSPORT
Autore:
NIELSEN OB; OVERGAARD K;
Indirizzi:
AARHUS UNIV,DEPT PHYSIOL DK-8000 AARHUS C DENMARK
Titolo Testata:
Acta Physiologica Scandinavica
fascicolo: 3, volume: 156, anno: 1996,
pagine: 247 - 256
SICI:
0001-6772(1996)156:3<247:IGACIS>2.0.ZU;2-H
Fonte:
ISI
Lingua:
ENG
Soggetto:
STIMULATED CONTRACTIONS; REPETITIVE STIMULATION; EXCITATION-FREQUENCY; POTASSIUM CHANGES; SARTORIUS MUSCLE; OUABAIN BINDING; TWITCH MUSCLE; FATIGUE; EXERCISE; FIBERS;
Keywords:
CONTRACTILITY; FATIGUE; SKELETAL MUSCLE; NA+; K+ GRADIENTS; NA+; K+ PUMP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
68
Recensione:
Indirizzi per estratti:
Citazione:
O.B. Nielsen e K. Overgaard, "ION GRADIENTS AND CONTRACTILITY IN SKELETAL-MUSCLE - THE ROLE OF ACTIVE NA+, K+ TRANSPORT", Acta Physiologica Scandinavica, 156(3), 1996, pp. 247-256

Abstract

Intensive contractile activity is associated with a significant net loss of K+ and a comparable gain of Na+ in the working muscle fibres. This leads to an increase in the interstitial and T-tubular K+ concentration and to a decrease in the T-tubular Na+ concentration. It is wellestablished that the exposure of muscles to high extracellular K+ or low extracellular Na+ inhibits contractile performance. More importantly. the combination of high extracellular K+ and low extracellular Nahas a much more pronounced inhibitory effect on force than the sum ofthe individual effects of the two ions. The inhibitory effects of high extracellular K+ or low extracellular Na+ can be alleviated within 5-10 min by acute hormonal stimulation of the Na+, K+ pump. In contrast. reductions in the capacity for active Na+, K+ transport by pre-incubation of isolated muscles with ouabain or by prior K+ depletion of theanimals significantly decreases contractile endurance during high-frequency electrical stimulation. Thus. muscles from K+-depleted rats exhibiting a 54% reduction in Na+, K+ pump concentration showed a 110% increase in force decline during 30 s of 60 Hz stimulation. Reducing theNa+, K+ pump capacity to a similar extent by pre-incubation with ouabain led to a comparable decrease in endurance. Moreover. reductions inthe Na+, K+ pump capacity were associated with an increased intracellular accumulation of Na+ during electrical stimulation. These observations support the notion that excitation-induced decreases in Na+. K+ gradients contribute to fatigue during intensive exercise and suggest that the capacity for active Na+, K+ transport is a determining factor for contractile endurance.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 07/07/20 alle ore 12:25:00