Data/hora: 05/06/2024 13:55:56

Provedor de dados: 	48	
País: 	Chile	
Título: 	Control of dual isoforms of Ca2+ release channels in muscle	
Autores: 	RÍOS,EDUARDO; ZHOU,JINGSONG.	
Data: 	2004-01-01	
Ano: 	2004	
Palavras-chave: 	Excitation-contraction coupling; Sarcoplasmic reticulum; Ca2+ sparks; Ryanodine receptor; Calcium-induced calcium release.	
Resumo: 	Here we compare excitation-contraction coupling in single muscle cells of frogs and rats. Because amphibians have isoform 3 (or b) of the ryanodine receptor/Ca2+ release channel, in addition to 1 (a), which is also present in the mammal, any extra feature present in the frog may in principle be attributed to isoform 3. Ca2+ release under voltage clamp depolarization has a peak and a steady phase in both taxonomic classes, but the peak is more marked in the frog, where the ratio of amplitudes of the two phases is voltage-dependent. This dependence is a hallmark of CICR. Confocal imaging identified Ca2+ sparks in the frog, but not in the voltage-clamped rat cells. Because Ca2+ sparks involve CICR both observations indicate that the contribution of CICR is minor or null in the mammal. The "couplon" model well accounts for observations in the frog, but assumes a structure that we now know to be valid only for the rat. A revised model is proposed, whereby the isoform 3 channels, located parajunctionally, are activated by CICR and contribute its characteristic global and local features. Several issues regarding the roles of different channels remain open to further study.	
Tipo: 	Journal article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000400012	
Editor: 	Sociedad de Biología de Chile	
Formato: 	text/html	
Fonte: 	Biological Research  v.37 n.4 2004