Simulation of rabbit A-type retinal horizontal cell that generates repetitive action potentials

Rabbit A-type retinal horizontal cells are classified into at least two types: cells that generate repetitive action potentials and those that do not. A mathematical model of these two types of cells based on the ionic current mechanisms has been proposed. Although the response of the former cell to 1-s positive current injection has so far been investigated by both electrophysiological and computational approaches, how this cell responds to much longer current injection has not been investigated. In the present study, I use this model to investigate the response of the former cell to a much longer current injection. Computer simulation indicates that when the stimulation period is relatively short, the membrane potential returns to the resting potential after current injection. In this case, the cell can repeatedly generate repetitive action potentials in response to stimulation. In contrast, when the stimulation period is relatively long, the membrane potential does not return to the resting potential but maintains the depolarized level even after current injection. In this case, the cell cannot repeatedly generate repetitive action potentials. When the present results were compared with those of the previous study, the difference in the response pattern after stimulation between the two types of horizontal cells was revealed.