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Modulation of store‐operated Ca 2+ entry in PC12 cells
Author(s) -
Prakash Y.S.,
Farmer Christopher
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1210-c
Subject(s) - chemistry , cyclopiazonic acid , glutamate receptor , endoplasmic reticulum , alkalosis , calcium , intracellular , stimulation , endocrinology , medicine , biophysics , acidosis , receptor , biochemistry , biology , organic chemistry
Both endoplasmic reticulum (ER) Ca 2+ release and Ca 2+ influx are essential components of intracellular Ca 2+ ([Ca 2+ ] i ) regulation in neuronal cells. Previous studies in non‐neuronal cells have shown that an acidotic state inhibits Ca 2+ influx via L‐type Ca 2+ channels, while alkalosis increases influx. Glutamate has also been shown to cause dysregulation of Ca 2+ influx. Store operated calcium entry (SOCE) that occurs following depletion of ER Ca 2+ stores is a newly defined mechanism in neurons. In this study, we examined the effects of altered pH and of glutamate on SOCE in differentiated rat pheochromocytoma (PC12) cells, a model for neuronal cells loaded with the Ca 2+ indicator fura‐2. Cells were exposed to zero Ca 2+ Tyrode's solution (pH 7.4) with 5 μM cyclopiazonic acid (CPA) to deplete the ER. 20 μM KBR‐7943 was used to inhibit Na + /Ca 2+ exchange. SOCE was then triggered by reintroduction of 2.5 mM Ca 2+ Tyrodes (pH 7.4). The cells were washed and the protocol repeated with altered pH (6.6–7.8; one pH change per protocol), altered temperature (35–39 °C) and with different concentrations of glutamate. SOCE was progressively inhibited with decreased pH or temperature, while alkalosis and increased temperature stimulated influx (p<0.05, ANOVA with repeated measures). Increasing glutamate concentrations progressively inhibited SOCE. These data show that SOCE in PC12 cells is susceptible to acidosis, temperature, and agonist stimulation: factors that can adversely affect neuronal function under pathological conditions. Accordingly, altered SOCE function may contribute to neuronal Ca 2+ overload under such conditions. Supported by the Departments of Anesthesiology, and Physiology and Biomedical Engineering, Mayo Clinic.