Subject: What mammalian cell gives off the greatest action potential?

We are developing a sensor that will read the action potential of a neuron, and 
we need to test it.  Neurons are very difficult to grow and expensive, so we 
are looking for a less expensive cell line that will give off an action 
potential when plated.  The key is that the cell needs to be able to do this 
without any other cells in the plate. We can use a drug to stimulate the firing 
of the cell.  Time is not a factor....if the cell only lives for a few minutes 
on the plate, that's fine, as long as we can still collect readings.

Re: What mammalian cell gives off the greatest action potential?