Growth cone calcium ion channels: properties, clustering, and functional roles.

Voltage-dependent Ca2+ channels appear to constitute a central component of signal transduction cascades in neuronal growth cones. By means of spatially selective superfusion in the subcellular range growth cone, Ca2+ channels were investigated quantitatively. Both principal types of Ca2+ channels, low voltage activated and high voltage activated Ca2+ channels were present in growth cones of cells regenerating neurites in culture as well as growth cones of differentiating neuronal precursor cells. Studies concerning their spatial distribution revealed a remarkable clustering of Ca2+ channels at the growth cone. Their possible functional roles in neurite growth, axonal pathfinding, and synaptogenesis are discussed.