RT info:eu-repo/semantics/article
T1 Calcium dynamics in catecholamine-containing secretory vesicles
A1 Moreno Díaz-Calderón, Alfredo
A1 Domínguez Lobatón, María Carmen
A1 Santo Domingo, Jaime
A1 Vay, Laura
A1 Hernández San Miguel, Esther
A1 Rizzuto, Rosario
A1 Montero Zoccola, María Teresa
A1 Álvarez Martín, Javier
K1 Calcio en el organismo
AB We have used an aequorin chimera targeted to the membrane of the secretory granules to monitor the free [Ca2+] inside them in neurosecretoryPC12 cells. More than 95% of the probe was located in a compartment with an homogeneous [Ca2+] around 40  M. Cell stimulation witheither ATP, caffeine or high-K+ depolarization increased cytosolic [Ca2+] and decreased secretory granule [Ca2+] ([Ca2+]SG). Inositol-(1,4,5)-trisphosphate, cyclic ADP ribose and nicotinic acid adenine dinucleotide phosphate were all ineffective to release Ca2+ from the granules.Changes in cytosolic [Na+] (0–140 mM) or [Ca2+] (0–10 M) did not modify either ([Ca2+]SG). Instead, [Ca2+]SG was highly sensitive tochanges in the pH gradient between the cytosol and the granules. Both carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) andnigericin, as well as cytosolic acidification, reversibly decreased [Ca2+]SG, while cytosolic alcalinization reversibly increased [Ca2+]SG. Theseresults are consistent with the operation of a H+/Ca2+ antiporter in the vesicular membrane. This antiporter could also mediate the effectsof ATP, caffeine and high-K+ on [Ca2+]SG, because all of them induced a transient cytosolic acidification. The FCCP-induced decrease in[Ca2+]SG was reversible in 10–15 min even in the absence of cytosolic Ca2+ or ATP, suggesting that most of the calcium content of the vesiclesis bound to a slowly exchanging Ca2+ buffer. This large store buffers [Ca2+]SG changes in the long-term but allows highly dynamic free [Ca2+]SGchanges to occur in seconds or minutes.
PB Elsevier Ltd.
SN 0143-4160
YR 2005
FD 2005
LK http://uvadoc.uva.es/handle/10324/5973
UL http://uvadoc.uva.es/handle/10324/5973
LA eng
NO Cell Calcium, 2005, vol. 37, p. 555-564
NO Producción Científica
DS UVaDOC
RD 27-abr-2024