A number of studies have begun to describe the effects of nerve growth factor (NGF) and the closely related brain-derived neurotrophic factor (BDNF) on the function of basal forebrain neurons. Little is known, however, about the effects of neurotrophins on membrane calcium conductances, which may play a role in growth factor signal transduction as well as regulation of neuronal excitability. Using the whole-cell patch-clamp technique, we investigated the effects of both NGF and BDNF on voltage-gated Ca(2+)-channel currents in cultured embryonic basal forebrain neurons. Exposure for 4–6 d to NGF significantly increased both the L-type and N-type components of the whole-cell current. Conversely, similar exposure to BDNF had no effect on Ca(2+)-channel currents. Consequently, one of the important effects of NGF may be to enhance calcium entry via voltage-dependent channels.