Electronic simulation of action potential propagation

Electronic technology was used to study action potential propagation from cell to cell. An electronic circuit was constructed to simulate an excitable membrane and eight such units were arranged to model two contiguous cells: two units for each surface membrane and one for each junctional membrane. The first unit was stimulated to threshold and propagation over the two cells was recorded. The time delay at the junction between cells was measured as a function of rJC, the radial shunt resistance at the cell junction. The experimental results showed that the time delay was about 1–2 msec when rJC values were changed from infinite down to about 100 KO; the time delay increased at lower rJC values and propagation was blocked when rJC was below 10 KΩ. Excitation of cell 1 caused hyperpolarization of unit 5 and depolarization of units 6, 7, 8 prior to triggering of the action potential (AP) in cell 2. Making the prejunctional membrane (unit 4) inexcitable did not prevent excitation of cell 2, reflecting the dependence on longitudinal current flow. AP propagation via capacitative coupling was also studied, and junctional delay increased when Cj was lowered. The model will be extended to study cell coupling via the electric field effect at the cell junction.