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Microheterogeneity of calcium signalling in dendrites
Author(s) -
PozzoMiller Lucas D.,
Connor John A.,
Andrews S. Brian
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.t01-1-00053.x
Subject(s) - intracellular , biophysics , calcium signaling , microbiology and biotechnology , endoplasmic reticulum , chemistry , calcium , hippocampal formation , cytosol , calcium in biology , extracellular , neuroscience , biology , biochemistry , organic chemistry , enzyme
Transient changes in the intracellular concentration of free Ca 2+ ([Ca 2+ ] i ) originating from voltage‐ or ligand‐gated influx and by ligand‐ or Ca 2+ ‐gated release from intracellular stores, trigger or modulate many fundamental neuronal processes, including neurotransmitter release and synaptic plasticity. Of the intracellular compartments involved in Ca 2+ clearance, the endoplasmic reticulum (ER) has received the most attention because it expresses Ca 2+ pumps and Ca 2+ channels, thus endowing it with the potential to act as both an intracellular calcium sink and store. We review here our ongoing work on the role of calcium sequestration into, and release from, ER cisterns and the role that this plays in the generation and termination of free [Ca 2+ ] i transients in dendrites of pyramidal neurons in hippocampal slices during and after synaptic activity. These studies have been approached by combining parallel microfluorometric measurements of free cytosolic [Ca 2+ ] i transients with energy‐dispersive X‐ray microanalytical measurements of total Ca content within specific dendritic compartments at the electron microscopy level. Our observations support the emerging realization that specific subsets of dendritic ER cisterns provide spatial and temporal microheterogeneity of Ca 2+ signalling, acting not only as a major intracellular Ca sink involved in active clearance mechanisms after voltage‐ and ligand‐gated Ca 2+ influx, but also as an intracellular Ca 2+ source that can be mobilized by a signal cascade originating at activated synapses.