Stimulation protocols

Dear All
We are using a rat cardiomyocyte prep on a MEA60-INV-BC.

We usually don't have any problems getting the preps to spontaneously beat but we would be interested in standardising beat rate etc. to allow easier comparison between different plates and batches. Therefore we have been looking at the possibility of using a stimulator to "drive" the plate at the desired rate.

We are using a STG1008 stimulus generator and our current stimulus protocol is a rectangular biphasic pulse (+250mV for 100uS and -250mV for 100uS) with a gap of 800uS.

This protocol however is only a first "guestimate" and may not be the optimium protocol to use.

Does anyone have a cardiomyocyte stimulation protocol they know works well? Thank you.
Steve

(My colleagues having some problems posting so I posted this on his behalf..Scott)

Dear Steve,

you might want to have alook at the paper from Meiry et al from the group of Ofer Binah, where stimulation of this cells is described. The actual protocol of course varies by size of the electrodes and cell density and size of the plated area.
Assuming you are using standard 30um TiN electrodes I would increase all parameters of your protocol : We use for HL-1 cells for example a biphasic pulse of +2V for 500-800us, then -2V for 500-800us. Due to these large pulses blanking circuit helps a lot to obtain easier to analyze signals.

Thomas

Meiry G, Reisner Y, Feld Y, Goldberg S, Rosen M, Ziv N & Binah O. (2001). Evolution of action potential propagation and repolarization in cultured neonatal rat ventricular myocytes. J Cardiovasc Electrophysiol 12, 1269-1277.