Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 1 de 1
Filtrar
Añadir filtros








Intervalo de año
1.
Biol. Res ; 37(4): 609-612, 2004. ilus
Artículo en Inglés | LILACS | ID: lil-437515

RESUMEN

Activation of Ca2+ release channels/ryanodine receptors (RyR) by the inward Ca2+ current (ICa) gives rise to Ca2+-induced Ca2+ release (CICR), the amplifying Ca2+ signaling mechanism that triggers contraction of the heart. CICR, in theory, is a high-gain, self-regenerating process, but an unidentified mechanism stabilizes it in vivo. Sorcin, a 21.6 kDa Ca2+-binding protein, binds to cardiac RyRs with high affinity and completely inhibits channel activity. Sorcin significantly inhibits both the spontaneous activity of RyRs in quiescent cells (visualized as Ca2+ sparks) and the ICa-triggered activity of RyRs that gives rise to [Ca2+]i transients. Since sorcin decreases the amplitude of the [Ca2+]i transient without affecting the amplitude of ICa, the overall effect of sorcin is to reduce the "gain" of excitation-contraction coupling. Immunocytochemical staining shows that sorcin localizes to the dyadic space of ventricular cardiac myocytes. Ca2+ induces conformational changes and promotes translocation of sorcin between soluble and membranous compartments, but the [Ca2+] required for the latter process (ED50 = ~200 mM) appears to be reached only within the dyadic space. Thus, sorcin is a potent inhibitor of both spontaneous and ICa-triggered RyR activity and may play a role in helping terminate the positive feedback loop of CICR.


Asunto(s)
Animales , Proteínas de Unión al Calcio , Canal Liberador de Calcio Receptor de Rianodina/metabolismo , Contracción Miocárdica/fisiología , Miocitos Cardíacos/metabolismo , Retículo Sarcoplasmático/metabolismo , Calcio/metabolismo , Inmunohistoquímica , Señalización del Calcio/fisiología
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA