Is the internal calcium regulation altered in type A botulinum toxin-poisoned motor endings?
The hypothesis according to which botulinum A toxin blocks acetylcholine release from motor endings by stimulating intracellular Ca2+ disposal systems was tested by recording presynaptic membrane currents from poisoned muscles. Calcium and calcium-activated potassium currents displayed amplitudes, time courses and stimulation frequency-dependent inactivation similar to those observed in unpoisoned preparations. This indicates that poisoned endings are no more efficient than normal ones in dealing with Ca2+ overloads.
Mallart
A
A
Laboratoire de Neurobiologie Cellulaire et Moléculaire, C.N.R.S., Gif sur Yvette, France.
Molgó
J
J
Angaut-Petit
D
D
Thesleff
S
S
D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism* / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009046:Motor Neurons / Q000187:drug effects / Q000378:metabolism*; D009469:Neuromuscular Junction / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000502:physiology; D011893:Rana esculenta
D015220:Calcium Channels; D001905:Botulinum Toxins; D011188:Potassium; D002118:Calcium