CHZ decreases the irregularity pacemaking through SK channels. A, The precision of pacemaking of a wild-type cerebellar Purkinje cell was monitored by following coefficient of variation of its interspike intervals. Addition of low concentration of cadmium to partially block voltage-gated calcium channels made the firing of the cell irregular. Iberiotoxin at 100 nm was then added to block BK channels. Despite the blockade of BK channels, 30 μm CHZ restored the precision of pacemaking to control conditions. The average coefficient of variation of interspike intervals (B) and firing rate (C) of five Purkinje cells following the experimental procedure described in A. *p < 0.05 (one-way ANOVA, followed by Bonferroni's correction). n.s., Not significant. D, The pacemaking of a Purkinje cell was made irregular with addition of cadmium, and the selective BK channel activator NS1619 was bath applied at a concentration of 30 μm. Although NS1619 was ineffective in restoring the precision of pacemaking, subsequent addition of 30 μm CHZ returned the coefficient of variation of interspike intervals to pre-cadmium levels. The average coefficient of variation of interspike intervals (E) and firing rate (F) of all the Purkinje cells examined following the experimental procedure described in D. *p < 0.05; n.s., Not significant; Ctrl, control; NS, NS1619.