Botulinum A toxin and tetanus toxin do not affect presynaptic membrane currents in mammalian motor nerve endings.
The hypothesis according to which BoTx and TeTx block neuromuscular transmission by impairing Ca2+ influx was tested by recording presynaptic membrane currents at motor endplates of the mouse by means of external electrodes. The use of K-channel blockers allowed us to observe inward Ca current which was unaffected by bath application of BoTx or TeTx at doses which block neuromuscular transmission.
D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects; D051379:Mice; D009046:Motor Neurons / Q000187:drug effects; D009469:Neuromuscular Junction / Q000187:drug effects*; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects; D013744:Tetanus Toxin / Q000494:pharmacology*
D007473:Ion Channels; D013744:Tetanus Toxin; D012964:Sodium; D001905:Botulinum Toxins; D011188:Potassium; D002118:Calcium