Use of neurotoxins to study Ca2+ channel functions.

The article contains a brief review on the properties and classification of voltage-dependent Ca2+ channels and on the organic blockers of the different channel types. The effects of peptide toxins from the venoms of Conus sp and of the spider Agelenopsis aperta on high voltage-activated Ca2+ channels are discussed. In addition, we present preliminary data on a novel peptide toxin purified from the venom of the spider Phoneutria nigriventer, which is a powerful blocker of L- and N-type Ca2+ channels.