Ca2+ channel toxins: Tools to study channel structure and function

A remarkable diversity of voltage‐dependent Ca2+ channels exists in the mammalian nervous system to subserve the broad and complicated roles that impulse‐generated changes in intracellular Ca2+ play in neuronal functions such as synaptic transmission, cell firing, gene expression, and related functional sequelae. A detailed understanding of how such temporally and subcellularly restricted changes in intracellular Ca2+ affect cellular and synaptic function requires selective pharmacological tools that can specifically dissect one channel apart from the operating neuron or neuronal system. A set of selective reagents currently available to the Ca2+ channel pharmacologist or physiologist has been provided by a variety of predatory animals from disparate phylogenetic origins. It is fortunate that these creatures invested in countless years of toxin engineering providing essential implements which otherwise might have been obtained only through an enormous effort on the part of current‐day scientists. This review will offer a discussion of the current understanding of the pharmacology and chemistry of important Ca2+ channel toxins in the context of the growing field of neuronal Ca2+ channel structure and function.