Intracellular Ca2+ pools in PC12 cells. Three intracellular pools are distinguished by their turnover and mechanisms of Ca2+ accumulation, storage, and release.
1991; Elsevier BV; Volume: 266; Issue: 30 Linguagem: Inglês
10.1016/s0021-9258(18)54904-8
ISSN1083-351X
AutoresCristina Fasolato, Michela Zottini, Emilio Clementi, Daniele Zacchetti, Jacopo Meldolesi, Tullio Pozzan,
Tópico(s)Neuroscience and Neuropharmacology Research
Resumo=ZOOp M of Ca2+/liter of cell water (< 30% of total exchangeable Ca2+) and takes up Ca2+ from the cytosol via a Ca2+-ATPase, blocked by thapsigargin.A second pool, ~4 0 0 bM/liter, is insensitive to both inositol 1,4,5trisphosphate, caffeine, and thapsigargin and is released by the Ca2+ ionophore ionomycin.This pool is probably heterogeneous and its intracellular localization and physiological roles remain undefined.The third pool, ~1 7 0 Mmoles of Ca2+/liter, was discharged by the combination of ionomycin together with a substance that collapsed intracellular pH gradients, such as monensin or NH4Cl.This indicates that the pool is acidic, at variance with the first two.When exocytosis was stimulated, the size of this pool declined, indicating its primary residence within secretory granules.In the conditions of our experiments no major transfer of Ca2+ among the pools seemed to occur.This is the first comprehensive description of non-cytosolic Ca2+ pools investigated in intact neurosecretory cells by non-invasive procedures.PC12 is a cell line originally developed from a rat pheochromocytoma (and therefore similar to chromaffin cells of that species) which is widely used, especially for studies of neurosecretion and nerve cells differentiation (2).In the preceding article (1) we have demonstrated that in these cells a single rapidly exchanging intracellular Ca2+ pool accounts for the [Ca'+]; responses
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