L- and T-type calcium channels in cultured neuronal cell lines are insensitive to tetanus toxin.
Possible effects of tetanus toxin (TeTox) on voltage-activated Ca2+ channels of the mouse neuroblastoma cell line N1E-115 and of the neuroblastoma x glioma hybrid cell line NG108-15 have been investigated using the whole-cell voltage clamp technique. Similar to N1E-115 cells, differentiated NG108-15 cells express transient (T-type) as well as long-lasting (L-type) Ca2+ channels. Using various treatment protocols N1E-115 and NG108-15 cells were exposed to TeTox externally and by internal dialysis. In the cells treated with TeTox normal Ca2+ channel activity was present, as measured by the voltage-activated Ba2+ currents under voltage clamp conditions. In addition, intracellular microelectrode recordings showed that TeTox did not block the Ca2+ action potential in N1E-115 cells. It is concluded that TeTox, in contrast to previously reported results, does not affect voltage-activated T- and L-type Ca2+ channels in cultured neuronal cell lines. The results also indicate that Ca2+ channel block is unlikely to be an explanation for the block of neurotransmitter release by TeTox in vivo.
van der Valk
J B
JB
Research Institute of Toxicology, University of Utrecht, The Netherlands.
Vijverberg
H P
HP
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects*; D002460:Cell Line; D005910:Glioma / Q000378:metabolism; D051379:Mice; D008839:Microelectrodes; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D013744:Tetanus Toxin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
D015220:Calcium Channels; D013744:Tetanus Toxin