Gap junctions are highly conductive channels that allow the direct tra
nsfer of intracellular messengers such as Ca2+ and inositol triphospha
te (IP3) between interconnected cells, In brain, astrocytes are couple
d extensively by gap junctions. We found here that gap junctions among
astrocytes in acutely prepared brain slices as well as in culture rem
ained open during ischemic conditions, Uncoupling first occurred after
the terminal loss of plasma membrane integrity. Gap junctions therefo
re may link ischemic astrocytes in an evolving infarct with the surrou
ndings. The free exchange of intracellular messengers between dying an
d potentially viable astrocytes might contribute to secondary expansio
n of ischemic lesions.