The dynamic activation of colicin Ia channels in planar bilayer lipid membrane

Dynamic activation of ion channels formed by colicin Ia; incorporated into a planar bilayer lipid membrane (BLM) was investigated by the voltage clamp technique using different step voltage stimuli. We have demonstrated a cri tical resting interval, Delta t(c), between two identical successive voltag e pulses. If the second pulse is applied within Delta t(c), it produces a p redictable current response. On the contrary, if the second pulse is applie d after Delta t(c), the current response cannot be reliably predicted. Comp uter simulations based on an idealized mathematical model, developed in thi s paper, qualitatively reproduce the system's dynamic responses to stimulus trains. The behavior of the ion channels, when the resting period exceeds Delta t(c), may be interpreted as a transient gain or loss or resetting of memory, as revealed by a specific sequence of electrical pulses used for st imulation. (C) 2000 Academic Press.