RyR1/SERCA1 cross-talk regulation of calcium transport in heavy sarcoplasmic reticulum vesicles.
Can J Physiol Pharmacol
; 81(3): 220-33, 2003 Mar.
Article
em En
| MEDLINE
| ID: mdl-12733821
ABSTRACT
We investigated the functional interdependence of sarco-endoplasmic reticulum Ca2+ ATPase isoform 1 and ryanodine receptor isoform 1 in heavy sarcoplasmic reticulum membranes by synchronous fluorescence determination of extravesicular Ca2+ transients and catalytic activity. Under conditions of dynamic Ca2+ exchange ATPase catalytic activity was well coordinated to ryanodine receptor activation/inactivation states. Ryanodine-induced activation of Ca2+ release channel leaks also produced marked ATPase activation in the absence of measurable increases in bulk free extravesicular Ca2+. This suggested that Ca2+ pumps are highly sensitive to Ca2+ release channel leak status and potently buffer Ca2+ ions exiting cytoplasmic openings of ryanodine receptors. Conversely, ryanodine receptor activation was dependent on Ca2+-ATPase pump activity. Ryanodine receptor activation by cytosolic Ca2+ was (i) inversely proportional to luminal Ca2+ load and (ii) dependent upon the rate of presentation of cytosolic Ca2+. Progressive Ca2+ filling coincided with progressive loss of Ca2+ sequestration rates and at a threshold loading, ryanodine-induced Ca2+ release produced small transient reversals of catalytic activity. These data indicate that attainment of threshold luminal Ca2+ loads coordinates sensitization of Ca2+ release channels with autogenic inhibition of Ca2+ pumping. This suggests that Ca2+-dependent control of Ca2+ release in intact heavy sarcoplasmic reticulum membranes involves a Ca2+-mediated "cross-talk" between sarco-endoplasmic reticulum Ca2+ ATPase isoform 1 and ryanodine receptor isoform 1.
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Base de dados:
MEDLINE
Assunto principal:
Retículo Sarcoplasmático
/
Cálcio
/
ATPases Transportadoras de Cálcio
/
Canal de Liberação de Cálcio do Receptor de Rianodina
Limite:
Animals
Idioma:
En
Revista:
Can J Physiol Pharmacol
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Canadá