α -latrotoxin of Black Widow Spider Venom Depolarizes the Plasma Membrane, Induces Massive Calcium Influx, and Stimulates Transmitter Release in Guinea Pig Brain Synaptosomes
Abstract
The effect of alpha-latrotoxin from black widow spider venom upon guinea pig cerebral cortical synaptosomes is described. Plasma membrane potential (delta psi p), in situ mitochondrial membrane potential (delta psi m), Ca2+ transport, gamma-amino[3H]butyrate release, [3H]noradrenaline release, and synaptosomal ATP were monitored under parallel conditions. Potentials were determined both isotopically and with a tetraphenylphosphonium-selective electrode. alpha-Latrotoxin depolarizes delta psi p selectively, both in the presence and absence of Ca2+. A slight toxin-induced depolarization of delta psi m is a consequence of a massive Ca2+ uptake across the plasma membrane. Depolarization of delta psi p is insensitive to tetrodotoxin, and Ca2+ entry is only partially inhibited by verapamil. Release of [3H]noradrenaline and gamma-amino[3H]butyrate is markedly stimulated by the toxin in the presence of Ca2+, and this effect is only slightly reduced in Ca2+-free conditions.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- December 1982
- DOI:
- 10.1073/pnas.79.24.7924
- Bibcode:
- 1982PNAS...79.7924N