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Ca 2+ dynamics in the lumen of the endoplasmic reticulum in sensory neurons: direct visualization of Ca 2+ ‐induced Ca 2+ release triggered by physiological Ca 2+ entry
Author(s) -
Solovyova N.,
Veselovsky N.,
Toescu E.C.,
Verkhratsky A.
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/21.4.622
Subject(s) - endoplasmic reticulum , biology , sensory system , calcium signaling , microbiology and biotechnology , stim1 , lumen (anatomy) , biophysics , calcium , neuroscience , intracellular , medicine
In cultured rat dorsal root ganglia neurons, we measured membrane currents, using the patch–clamp whole‐cell technique, and the concentrations of free Ca 2+ in the cytosol ([Ca 2+ ] i ) and in the lumen of the endoplasmic reticulum (ER) ([Ca 2+ ] L ), using high‐ (Fluo‐3) and low‐ (Mag‐Fura‐2) affinity Ca 2+ ‐sensitive fluorescent probes and video imaging. Resting [Ca 2+ ] L concentration varied between 60 and 270 μM. Activation of ryanodine receptors by caffeine triggered a rapid fall in [Ca 2+ ] L levels, which amounted to only 40–50% of the resting [Ca 2+ ] L value. Using electrophysiological depolarization, we directly demonstrate the process of Ca 2+ ‐induced Ca 2+ release triggered by Ca 2+ entry through voltage‐gated Ca 2+ channels. The amplitude of Ca 2+ release from the ER lumen was linearly dependent on I Ca .