Depolarizing prepotentials are Na+ dependent in CA1 pyramidal neurons.

Slow depolarizing prepotentials are important in controlling the frequency of neuronal firing in CA1 pyramidal cells. The ionic basis for subthreshold depolarizing potentials was examined in these experiments. Depolarizing prepotentials were concluded to be due to an inward Na+ current because they were blocked by reducing extracellular Na+ and by extracellular application of tetrodotoxin (TTX), and they were unaffected by blockers of inward Ca2+ currents.