2026-04-28T21:12:57Zhttps://uvadoc.uva.es/oai/request

oai:uvadoc.uva.es:10324/59802024-12-16T12:05:20Zcom_10324_1133com_10324_931com_10324_894col_10324_1209

Santo Domingo Mayoral, Jaime Fonteriz García, Rosalba Inés Domínguez Lobatón, María Carmen Montero Zoccola, María Teresa Moreno Díaz-Calderón, Alfredo Álvarez Martín, Javier Calcio - Metabolismo Producción Científica We have investigated the dynamics of the free [Ca2+] inside the secretory granules of neurosecretory PC12 and INS1 cells using a low-Ca2+-affinity aequorin chimera fused to synaptobrevin-2. The steady-state secretory granule [Ca2+] ([Ca2+]SG] was around 20–40 lM in both cell types, about half the values previously found in chromaffin cells. Inhibition of SERCA-type Ca2+ pumps with thapsigargin largely blocked Ca2+ uptake by the granules in Ca2+-depleted permeabilized cells, and the same effect was obtained when the perfusion medium lacked ATP. Consistently, the SERCA-type Ca2+ pump inhibitor benzohydroquinone induced a rapid release of Ca2+ from the granules both in intact and permeabilized cells, suggesting that the continuous activity of SERCA-type Ca2+ pumps is essential to maintain the steady-state [Ca2+]SG. Both inositol 1,4, 5-trisphosphate (InsP3) and caffeine produced a rapid Ca2+ release from the granules, suggesting the presence of InsP3 and ryanodine receptors in the granules. The response to high-K+ depolarization was different in both cell types, a decrease in [Ca2+]SG in PC12 cells and an increase in [Ca2+]SG in INS1 cells. The difference may rely on the heterogeneous response of different vesicle populations in each cell type. Finally, increasing the glucose concentration triggered a decrease in [Ca2+]SG in INS1 cells. In conclusion, our data show that the secretory granules of PC12 and INS1 cells take up Ca2+ through SERCA-type Ca2+ pumps and can release it through InsP3 and ryanodine receptors, supporting the hypothesis that secretory granule Ca2+ may be released during cell stimulation and contribute to secretion. 2014-09-16 2014-09-16 2010 info:eu-repo/semantics/article Cellular and Molecular Neurobiology, 2010, vol. 30, p. 1267-1274 0272-4340 http://uvadoc.uva.es/handle/10324/5980 10.1007/s10571-010-9572-2 1267 1274 Cellular and Molecular Neurobiology 30 eng info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-nd/4.0/ Attribution-NonCommercial-NoDerivatives 4.0 International Springer Verlag