Activation of the sarcoplasmic reticulum Ca2+-ATPase induced by exercise.
Biochim Biophys Acta
; 1279(2): 203-13, 1996 Mar 13.
Article
em En
| MEDLINE
| ID: mdl-8603088
ABSTRACT
Prolonged exercise has been shown to cause disruption of intracellular calcium homeostasis in skeletal muscle, which is normally maintained by the sarcoplasmic reticulum (SR) Ca2+-ATPase. We have investigated the response of this enzyme to increased intracellular calcium levels by investigating the functional and physical characteristics of the SR Ca2+-ATPase and membrane lipids following 2 h of treadmill running and throughout a period of post-exercise recovery. The Ca2+-ATPase of SR membranes purified from exercised rats shows increases in enzymatic activity correlating with post-exercise recovery time. Corresponding increases in active Ca2+-ATPase pump units are observed, as measured by the concentration of phosphorylated enzyme intermediate formed from ATP. However, catalytic turnover rates of the Ca2+-ATPase are unchanged. Using spin-label electron paramagnetic resonance to assess both membrane fluidity and associations between individual Ca2+-ATPase polypeptide chains, we find no exercise-induced alterations in membrane dynamics which could explain the observed increases in Ca2+-ATPase activity. Nor do we find evidence for altered membrane purification as a result of exercise. We suggest that the cell responds to the challenge of increased cytosolic calcium levels by increasing the proportion of functional SR Ca2+-ATPase proteins in the membrane for the rapid restoration of calcium homeostasis.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Retículo Sarcoplasmático
/
ATPases Transportadoras de Cálcio
/
Esforço Físico
Limite:
Animals
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Estados Unidos