Brevetoxin modulates neuronal sodium channels in two cell lines derived from rat brain.
Single Na+ channel currents were recorded from cell-attached membrane patches from two neuronal cell lines derived from rat brain, B50 and B104, and compared before and after exposure of the cells to purified brevetoxin, PbTx-3. B50 and B104 Na+ channels usually exhibited fast activation and inactivation as is typical of TTX-sensitive Na+ channels. PbTx-3 modified channel gating in both cell lines. PbTx-3 caused (1) significant increases in the frequency of channel reopening, indicating a slowing of channel inactivation, (2) a change in the voltage dependence of the channels, promoting channel opening during steady-state voltage clamp of the membrane at voltages throughout the activation range of Na+ currents, but notably near the resting potential of these cells (-60 - -50 mV), and (3) a significant, 6.7 mV hyperpolarized shift in the threshold potential for channel opening. Na+ channel slope conductance did not change in PbTx-3-exposed B50 and B104 neurons. These effects of Pbx-3 may cause hyperexcitability as well as inhibitory effects in intact brain.
Purkerson
S L
SL
University of Miami Rosenstiel School of Marine and Atmospheric Science, Division of Marine Biology and Fisheries, NIEHS Marine and Freshwater Biomedical Sciences Center, FL 33149, USA.
Baden
D G
DG
Fieber
L A
LA
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D015640:Ion Channel Gating / Q000187:drug effects*; D008387:Marine Toxins / Q000633:toxicity*; D009474:Neurons / Q000378:metabolism*; D035964:Oxocins; D018408:Patch-Clamp Techniques; D051381:Rats; D015222:Sodium Channels / Q000378:metabolism*; D013997:Time Factors; D000095702:Polyether Toxins
D008387:Marine Toxins; D035964:Oxocins; D015222:Sodium Channels; C053342:brevetoxin; D000095702:Polyether Toxins