A microcomputer-based system for data acquisition and analysis of step-like current jumps due to the opening of single ionic channels in model membranes

Abstract At the cell surface, passive transport is controlled by membrane protiens forming hydrophilic pores (or channels) which span the hydrophobic core of the lipid bilayer. Gating mechanisms determine the occurrence of very small and fast step-like current jumps. We developed an intelligent system to acquire and to analyze signals due to the opening and closing of ionic single channels. A specific algorithm allows us to recognize channel current transitions and to discard false events due to noise peaks or to unwelcome fluctuations of the signal. Statistics of the single channel amplitude and mean life-time can be performed. We report the results obtained from analyzing the characteristics of the gramicidin A single channel in phosphatidylserine model memebranes. Mean current values of 2.08 ± 0.01 pA and lifetimes of 101 ± 3 ms, were measured at 100mV applied potentials in KC1 100 mM solution.