Tetanus toxin blocks potassium-induced transmitter release and rearrangement of intramembrane particles at pure cholinergic synaptosomes.
We have studied the action of tetanus toxin on the release of acetylcholine from a subcellular fraction of cholinergic nerve terminals (synaptosomes) isolated from the Torpedo electric organ. We have also studied the morphological changes induced by chemical stimulation on the presynaptic plasma membrane of poisoned synaptosomes. These changes were studied by means of freeze-fracture techniques. We found that tetanus toxin blocks the release of acetylcholine from isolated nerve terminals in a dose-dependent manner. The maximal inhibition is achieved at a concentration of 12.5 nM in 10 min. This effect is prevented by tetanus toxin antiserum. Tetanus toxin also blocks the rearrangement of intramembrane particles at plasma membrane of poisoned synaptosomes, specifically the decrease of small (less than or equal to 9.5 nm diameter) intramembranous particles at the protoplasmic hemimembrane leaflet and the increase of large (greater than 9.5 nm diameter) intramembrane particles at the external hemimembrane leaflet induced by potassium stimulation. These results suggest that intramembrane particle rearrangement could be related to acetylcholine secretion.
Egea
G
G
Departament de Biologia Cellular i Anatomia Patològica, Universitat de Barcelona, Spain.
Rabasseda
X
X
Solsona
C
C
Marsal
J
J
Bizzini
B
B
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001905:Botulinum Toxins / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D011188:Potassium / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects*; D013744:Tetanus Toxin / Q000494:pharmacology*; D014101:Torpedo
D013744:Tetanus Toxin; D001905:Botulinum Toxins; D000109:Acetylcholine; D011188:Potassium