Investigating the Contribution of BK Channel in the Firing Activity of Cerebellar Purkinje Cells Using Computer Simulation

Background: BK channels are highly conductive calcium (Ca2+)-activated potassium (K+) channels. These channels are available on the membrane of many types of neurons including cerebellar Purkinje cells. Several experimental studies have used iberiotoxin, a BK-specific channel blocker, to investigate the role of BK channels on electrophysiological behavior of Purkinje cells. Due to controversial results of mentioned research, we used computer simulation to assess the functional contribution of BK channels to the firing activity of Purkinje cells. Methods: Two realistic models of Purkinje cells with and without dendritic branches were used to investigate the functional contribution of BK channel to the firing activity of Purkinje cells. The simulations were performed in NEURON 7.1 simulator. Findings: The simulations using single compartment model (without dendritic branches) demonstrated that blocking BK channels slightly increased firing rate from 40 to 45 Hz. Simulation with the multi-compartmental model, which included the dendrites as well as the soma, showed that blocking BK channels abolished Ca2+ spikes while sodium (Na+) spikes remained unchanged. Conclusion: The results obtained from simulations indicated that blocking BK channels has no significant effect on the tonic firing rate of Purkinje cells. Simulations also showed that dendritic BK channels have more effect on firing behavior of Purkinje cells compared with somatic BK channels. Keywords: Purkinje cell, Calcium-activated potassium channel, Spike potential