Measurement of Intraneuronal Free Calcium Using the Fluorescent Probe Technique
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The distribution of Ca2+
within the cell is complex and involves binding to cell macromolecules and compartmentalization within the subcellular organelles
(1
). Normal physiological functions of the cell are regulated by changes in intracellular free Ca2+
([Ca2+
]i
), which ranges from 0.1 to 0.3 �M
. This low concentration is regulated by energy-dependent transport systems located in plasma membrane, endoplasmic reticulum,
and mitochondria (1
). Cytosolic [Ca2+
]i
within the cell are elevated either through Ca2+
-influx or by Ca2+
-release from intracellular stores. Such increases in [Ca2+
]i
have been reported to activate several intracellular Ca2+
-dependent reactions including production of second messengers (2
,3
), spontaneous release of neurotransmitters (4
), phosphorylation of proteins (5
), and activity of proteases (6
). Cells need to maintain a fine balance of these Ca2+
homeostatic mechanisms in order to function normally, and any major disturbance in these systems will activate destructive
events leading to neuronal injury (7
–10
).
