T. Yamasaki et al., ANALYSIS OF INTRACELLULAR AND INTERCELLULAR CALCIUM SIGNALING IN A MOUSE MALIGNANT GLIOMA CELL-LINE, Journal of neurosurgery, 81(3), 1994, pp. 420-426
Intra- and intercellular calcium signaling in glioma cells was examine
d by mechanical stimulation of a monolayer cell line of methylcholanth
rene-induced mouse ependymoblastoma, 203-glioma, with a fine round tip
glass needle. A fura-2 fluorescence image of the glioma revealed a fo
ur- to eightfold increase in the cytosolic calcium ion concentration i
n directly stimulated signal cells. The increased calcium spread to su
rrounding cells at a speed of 20 mu m/sec for a distance of up to 200
mu m. Calcium was transmitted between adjacent cells and even in cells
up to 200 mu m distant from the initially stimulated cell. Microinjec
tion of Lucifer yellow dye showed no gap junctional communication betw
een cells. Depletion of extracellular calcium ion inhibited both cytos
olic calcium elevation and propagation to neighboring cells by mechani
cal stimulus. An intracellular calcium blocker, TMB-8, eliminated the
cytosolic calcium mobilization in a mechanically stimulated cell, but
had no effect on calcium diffusion to surrounding cells. Nifedipine an
d verapamil, antagonists of voltage-dependent calcium channels, did no
t act on the mechanically induced calcium response. This suggests that
some stimulating factor may trigger transmission of calcium, which ma
y be ejected directly from single stimulated cells and mediated via a
membrane receptor but not through a gap junction. The calcium signalin
g in a mechanically stimulated cell may be related to both an influx a
nd a redistribution of intracellular calcium from internal stores, whi
le calcium propagation to neighboring cells may involve calcium influx
alone.