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Maitotoxin-induced membrane current in neuroblastoma cells
1Department of Pharmacology, Northwestern University Medical School, Chicago, IL 60611.
Brain Research
|October 20, 1987
Summary
Maitotoxin (MTX) activates calcium channels in neuroblastoma cells, causing membrane depolarization. However, the MTX-induced current does not flow through these channels, suggesting MTX may form its own membrane pore.
Area of Science:
- Neuroscience
- Marine Biology
- Pharmacology
Background:
- Maitotoxin (MTX) is a potent marine toxin from Gambierdiscus toxicus.
- Understanding MTX's cellular mechanisms, particularly its interaction with ion channels, is crucial.
Purpose of the Study:
- To investigate whether Maitotoxin (MTX) activates calcium channels in cultured neuroblastoma cells (N1E-115).
- To characterize the nature of the MTX-induced current and its relationship to calcium channels.
Main Methods:
- Electrophysiological recordings (voltage clamp) on N1E-115 cells.
- Application of MTX and calcium channel blockers (verapamil, La3+).
- Analysis of membrane currents and depolarization in response to MTX and ion removal/blockade.
Main Results:
- MTX induced membrane depolarization, dependent on external Ca2+.
- MTX initially increased and then decreased Ba2+ currents through Type I and Type II calcium channels.
- MTX-induced currents were antagonized by calcium channel blockers but persisted after blocker washout, exhibiting inward rectification.
Conclusions:
- The MTX-induced current does not flow through endogenous calcium channels.
- MTX may induce a novel pore in the cell membrane with calcium channel-like pharmacological properties.