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A rapid exocytosis mode in chromaffin cells with a neuronal phenotype
Author(s) -
Ardiles Alvaro O.,
Maripillán Jaime,
Lagos Verónica L.,
Toro Rodrigo,
Mora Italo G.,
Villarroel Lorena,
Alés Eva,
Borges Ricardo,
Cárdenas Ana M.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.04080.x
Subject(s) - exocytosis , microbiology and biotechnology , neurite , vesicle , chromaffin cell , synaptic vesicle , biology , membrane potential , intracellular , secretion , adrenal medulla , chemistry , biophysics , catecholamine , neuroscience , endocrinology , in vitro , biochemistry , membrane
We have used astrocyte‐conditioned medium (ACM) to promote the transdifferentiation of bovine chromaffin cells and study modifications in the exocytotic process when these cells acquire a neuronal phenotype. In the ACM‐promoted neuronal phenotype, secretory vesicles and intracellular Ca 2+ rise were preferentially distributed in the neurite terminals. Using amperometry, we observed that the exocytotic events also occurred mainly in the neurite terminals, wherein the individual exocytotic events had smaller quantal size than in undifferentiated cells. Additionally, duration of pre‐spike current was significantly shorter, suggesting that ACM also modifies the fusion pore stability. After long exposure (7–9 days) to ACM, the kinetics of catecholamine release from individual vesicles was markedly accelerated. The morphometric analysis of vesicle diameters suggests that the rapid exocytotic events observed in neurites of ACM‐treated cells correspond to the exocytosis of large dense‐core vesicles (LDCV). On the other hand, experiments performed in EGTA‐loaded cells suggest that ACM treatment promotes a better coupling between voltage‐gated calcium channels (VGCC) and LDCV. Thus, our findings reveal that ACM promotes a neuronal phenotype in chromaffin cells, wherein the exocytotic kinetics is accelerated. Such rapid exocytosis mode could be caused at least in part by a better coupling between secretory vesicles and VGCC.