RT info:eu-repo/semantics/article
T1 Ca 2+ induced Ca 2+ Release in Chromaffin Cells Seen from inside the ER with Targeted Aequorin
A1 Alonso Alonso, María Teresa
A1 Barrero, María José
A1 Michelena, Pedro
A1 Carnicero Gila, Estela María
A1 Cuchillo Ibáñez, Inmaculada
A1 García, Antonio G.
A1 García-Sancho Martín, Francisco Javier
A1 Montero Zoccola, María Teresa
A1 Álvarez Martín, Javier
K1 Calcio - Metabolismo
AB The presence and physiological role of Ca 2+induced Ca 2+release (CICR) in nonmuscle excitablecells has been investigated only indirectly through measurementsof cytosolic [Ca 2+] ([Ca 2+]c). Using targetedaequorin, we have directly monitored [Ca 2+] changesinside the ER ([Ca 2+]ER) in bovine adrenal chromaffincells. Ca 2+entry induced by cell depolarization triggereda transient Ca 2+release from the ER that washighly dependent on [Ca 2+]ERand sensitized by lowconcentrations of caffeine. Caffeine-induced Ca 2+releasewas quantal in nature due to modulation by[Ca 2+]ER. Whereas caffeine released essentially all theCa 2+from the ER, inositol 1,4,5-trisphosphate (InsP3)-producing agonists released only 60Ð80%. Both InsP3and caffeine emptied completely the ER in digitoninpermeabilizedcells whereas cyclic ADP-ribose had noeffect. Ryanodine induced permanent emptying of theCa 2+stores in a use-dependent manner after activationby caffeine. Fast confocal [Ca 2+]cmeasurementsshowed that the wave of [C 2+]cinduced by 100-ms depolarizingpulses in voltage-clamped cells was delayedand reduced in intensity in ryanodine-treated cells. Ourresults indicate that the ER of chromaffin cells behavesmostly as a single homogeneous thapsigargin-sensitiveCa 2+pool that can release Ca 2+both via InsP3receptorsor CICR.
PB The Rockefeller University Press,
SN 0021-9525
YR 1999
FD 1999
LK http://uvadoc.uva.es/handle/10324/5951
UL http://uvadoc.uva.es/handle/10324/5951
LA eng
NO Journal of Cell Biology, Enero 1999, vol. 144, n. 2, p. 241-254
NO Producción Científica
DS UVaDOC
RD 23-nov-2024