Spider toxins selectively block calcium currents in drosophila

Abstract Toxins from spider venom, originally purified for their ability to block synaptic transmission in Drosophila, are potent and specific blockers of Ca 2+ currents measured in cultured embryonic Drosophila neurons using the whole-cell, patch-clamp technique. Differential actions of toxins from two species of spiders indicate that different types of Drosophila neuronal Ca 2+ currents can be pharmacologically distinguished. Hololena toxin preferentially blocks a non-inactivating component of the current, whereas Plectreurys toxin blocks both inactivating and non-inactivating components. These results suggest that block of a non-inactivating Ca 2+ current is sufficient to block neurotransmitter release at Drosophila neuromuscular junction.