Calcium dependence of ryanodine-sensitive calcium channels from brain cortex endoplasmic reticulum.
Endoplasmic reticulum vesicles isolated from rat brain cortex and fused with lipid bilayers displayed ryanodine-sensitive calcium channels, with three cytoplasmic calcium dependences. A: Channels (n=5) stimulated by Ca2+ (K0.5=1.2 microM and nHill=1.9) and not inhibited up to 0.5 mM Ca2+. B: Channels (n=14) cooperatively activated (K0.5=6.9 microM and nHill=1.8), and inhibited by Ca2+ (K0.5=152 microM and nHill=1.8). C: Low Po (<0.1) channels (n=22), non-cooperatively activated and inhibited with the same K0.5=26.3 microM Ca2+. These three types of responses to cytoplasmic [Ca2+] may underlie separate calcium release pathways in neurons of rat brain cortex.
Marengo
J J
JJ
Departamento de Fisiolgía y Biofisica, Facultad de Medicina, Universidad de Chile, Santiago.
Bull
R
R
Hidalgo
C
C
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004594:Electrophysiology; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D007295:Inositol Phosphates / Q000378:metabolism; D008051:Lipid Bilayers; D008297:Male; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012433:Ryanodine / Q000378:metabolism / Q000494:pharmacology*; D012530:Saxitoxin / Q000378:metabolism
D015220:Calcium Channels; D007295:Inositol Phosphates; D008051:Lipid Bilayers; D010743:Phospholipids; D012433:Ryanodine; D012530:Saxitoxin; D002118:Calcium