Expression of gap junction genes in astrocytes and C6 glioma cells.

The expression of the gap junction genes coding for the liver-type connexin32 and the heart-type connexin43 was examined in primary cultures of astrocytes and in cultures of C6 glioma cells. In both cell types, only connexin43 mRNA was detectable. However, the level of this mRNA was greatly reduced in C6 glioma cells compared to astrocytes. This was consistent with the further observation that astrocytes in primary culture were extensively dye-coupled, whereas such coupling was very restricted in cultures of C6 glioma cells. Connexin43 was immunocytochemically localized in astrocytes, but was not readily detected in C6 cells.