ROLE OF EXTRACELLULAR-MATRIX MOLECULES IN THE DEVELOPMENT OF THE SODIUM CURRENT IN QUAIL MESENCEPHALIC NEURAL CREST CELLS

The occurrence of the voltage-dependent sodium current has been studied in developing neurons from quail mesencephalic neural crest on different substrates, using the whole-cell patch clamp technique. Explants from 9-12 somite embryos were cultured on dishes coated with type I collagen, fibronectin, laminin or on plastic dishes in a chemically defined medium. After 18 h of culture the sodium current was observed in 70 % of the neurons tested, and at 24 h some of these neurons were able to generate an action potential. After 18-25 h cells grown on fibronectin- or collagen I-coated dishes showed a significantly higher occurrence of the sodium current (83 % and 84 % respectively) as compared to cells grown on uncoated plastic dishes (51 %). Moreover, in the presence of fibronectin, the current density of the sodium current was more than doubled in comparison with cells grown on other substrates.