2026-04-27T15:10:02Zhttps://uvadoc.uva.es/oai/request

oai:uvadoc.uva.es:10324/59732024-12-16T12:05:43Zcom_10324_1133com_10324_931com_10324_894col_10324_1209

Moreno Díaz-Calderón, Alfredo Domínguez Lobatón, María Carmen Santo Domingo Mayoral, Jaime Vay, Laura Hernández San Miguel, Esther Rizzuto, Rosario Montero Zoccola, María Teresa Álvarez Martín, Javier 2014-09-16T08:47:12Z 2014-09-16T08:47:12Z 2005 Cell Calcium, 2005, vol. 37, p. 555-564 0143-4160 http://uvadoc.uva.es/handle/10324/5973 10.1016/j.ceca.2005.02.002 555 564 Cell Calcium 37 We have used an aequorin chimera targeted to the membrane of the secretory granules to monitor the free [Ca2+] inside them in neurosecretory PC12 cells. More than 95% of the probe was located in a compartment with an homogeneous [Ca2+] around 40 M. Cell stimulation with either 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 to changes in the pH gradient between the cytosol and the granules. Both carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) and nigericin, as well as cytosolic acidification, reversibly decreased [Ca2+]SG, while cytosolic alcalinization reversibly increased [Ca2+]SG. These results are consistent with the operation of a H+/Ca2+ antiporter in the vesicular membrane. This antiporter could also mediate the effects of 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 vesicles is bound to a slowly exchanging Ca2+ buffer. This large store buffers [Ca2+]SG changes in the long-term but allows highly dynamic free [Ca2+]SG changes to occur in seconds or minutes. eng info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Attribution-NonCommercial-NoDerivatives 4.0 International Calcio en el organismo Calcium dynamics in catecholamine-containing secretory vesicles info:eu-repo/semantics/article