Immunocytochemical localization of NaCh6 in cultured spinal cord astrocytes

The expression of the alpha-subunit of voltage-gated sodium channel 6 (NaCh6) was examined in cultures of astrocytes from E18 rat spinal cord by using an antibody specific for NaCh6. Stellate cells with processes and flat, pancake-like astrocytes are the two morphological types predominantly present in these cultures. The antibody to NaCh6 labeled clusters at the cell body and along the length of the processes in stellate, process-bearing cells. Weak staining was observed in the flat, pancake-like astrocytes. Together with previous studies (Black et al., Mol Brain Res 23:235-245, 1994, Glia 14:133-144, 1995) that show that stellate cells express NaChs II and III (but not NaCh I) and flat cells express NaCh II, these results support the conclusions that there are different patterns of sodium channel expression between flat and stellate astrocytes and that multiple channel isoforms are expressed within the same cell. This study also suggests that NaCh6 may contribute to the electrical properties found in stellate astrocytes.