Open AccessCellular mechanism for spontaneous calcium oscillations in astrocytes 1
Author(s) -
WANG Tongfei,
ZHOU Chen,
TANG Aihui,
WANG Shiqiang,
CHAI Zhen
Publication year - 2006
Publication title -
acta pharmacologica sinica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.514
H-Index - 90
eISSN - 1745-7254
pISSN - 1671-4083
DOI - 10.1111/j.1745-7254.2006.00397.x
Subject(s) - thapsigargin , ryanodine receptor , endoplasmic reticulum , extracellular , hippocampal formation , biophysics , intracellular , chemistry , tetrodotoxin , calcium , medicine , endocrinology , biology , biochemistry
Aim: To determine the Ca 2+ source and cellular mechanisms of spontaneous Ca 2+ oscillations in hippocampal astrocytes. Methods : The cultured cells were loaded with Fluo‐4 AM, the indicator of intracellular Ca 2+ , and the dynamic Ca 2+ transients were visualized with confocal laser‐scanning microscopy. Results : The spontaneous Ca 2+ oscillations in astrocytes were observed first in co‐cultured hippocampal neurons and astrocytes. These oscillations were not affected by tetrodotoxin (TTX) treatment and kept up in purity cultured astrocytes. The spontaneous Ca 2+ oscillations were not impacted after blocking the voltage‐gated Ca 2+ channels or ethylenediamine tetraacetic acid (EDTA) bathing, indicating that intracellular Ca 2+ elevation was not the result of extracellular Ca 2+ influx. Furthermore, the correlation between the spontaneous Ca 2+ oscillations and the Ca 2+ store in endoplasmic reticulum (ER) were investigated with pharmacological experiments. The oscillations were: 1) enhanced when cells were exposed to both low Na + (70 mmol/L) and high Ca 2+ (5 mmol/L) solution, and eliminated completely by 2 μmol/L thapsigargin, a blocker of sarcoplasmic reticulum Ca 2+ ‐ATPase; and 2) still robust after the application with either 50 μmol/L ryanodine or 400 μmol/L tetracaine, two specific antagonists of ryanodine receptors, but depressed in a dose‐dependent manner by 2‐APB, an InsP3 receptors (InsP 3 R) blocker. Conclusion : InsP 3 R‐induced ER Ca 2+ release is an important cellular mechanism for the initiation of spontaneous Ca 2+ oscillation in hippocampal astrocytes.