Ionic currents of Drosophila embryonic neurons derived from selectively cultured CNS midline precursors

In order to investigate the electrogenesis of defined cell populations, we applied an in vitro system that allows the selective culturing of individua l Drosophila CNS precursors under different conditions. CNS midline (ML) pr ecursors prepared from gastrula stage embryos gave rise to progeny cells wi th neuronal and glial morphology that expressed specific markers. Using who le-cell patch-clamp recordings, a detailed description of ionic currents pr esent in this defined cell population is provided. Most ionic currents of c ultured ML neurons were similar to other cultured Drosophila neurons, even though their embryonic origin is different. They displayed at least two vol tage-gated potassium currents, a voltage-gated sodium, two voltage-gated ca lcium currents, and responded to the neurotransmitters ACh and GABA, They s howed homogeneity in action potential firing properties, generating only a single spike even upon sustained depolarization. Interestingly, although th e expression of the voltage-gated potassium currents appeared to be highly cell autonomous, for all other currents significant changes were observed i n the presence of fiber contacts. (C) 2000 John Wiley & Sons, Inc.