Role of voltage-sensitive calcium channels in mitogenic stimulation of neuroblasts.

The present study examines the role of Ca2+ in the regulation of sympathetic neuroblast mitosis. Employing a fully defined neuroblast culture system, we previously found that insulin growth factors (IGFs), depolarization and vasoactive intestinal peptide (VIP) regulated precursor mitosis. We now report that Ca2+ entry via voltage-sensitive channels was required for depolarization-stimulated mitogenesis. Ca2+ channel blockade with nitrendipine completely inhibited the increase in [3H]thymidine incorporation elicited by depolarizing stimuli including 30 mM KCl and the Na+ channel agonist veratridine. However, Ca2+ channel activity was not involved in the stimulation of DNA synthesis by IGFs or VIP. Thus, neuroblast mitosis may be regulated by multiple intracellular as well as extracellular signals.