Mibefradil Inhibition of T-Type Calcium Channels in Cerebellar Purkinje Neurons

The antihypertensive agent mibefradil completely and reversibly inhibited T-type calcium channels in freshly isolated rat cerebellar Purkinje neurons. The potency of mibefradil was increased at less hyperpolarized holding potentials, and the apparent affinity was correlated with the degree of channel inactivation. At 35°, the apparent dissociation constant K_app was 1 μm at a holding voltage of −110 mV (corresponding to...