Are undifferentiated PC12 rat pheochromocytoma cells electrically excitable?

Undifferentiated rat pheochromocytoma PC12 cells were current clamped using the whole cell technique. Measurements of cell membrane resting potentials (RMP) gave values in the -30 and -50 mV range. Cell input resistance was between 200 and 400 Mohm. After blockade of K⁺ currents with intracellular Cs⁺, cell membrane depolarization showed that PC12 cells are able to generate active responses (i.e., calcium action potentials followed by after-hyperpolarizations partially blocked by tetraethylammonium). Taken together, our results indicate that PC12 cells do not require exposure to nerve growth factor to become electrically excitable.