Removing non-random artifacts from patch clamp traces

Abstract

Analysis and interpretation of current records from cellular membranes or lipid bilayers is complicated by perturbations. These perturbations can originate from random noise or deterministic artifacts as capacitive currents caused by step depolarization's, drift, 50 Hz pick up or microphonics. Accurate removal of deterministic perturbations is a prerequisite for further analysis of ion channel kinetics. In this report we present two methods developed for parameter estimation of such artifacts in order to remove these perturbations from single channel patch clamp traces. For both methods artifact removal does not require sweeps lacking channel activity. The first method was designed to extract artifacts from sweeps showing moderate channel activity. Within a certain number of sweeps the artifacts should remain rather constant. The second method allows for artifact removal from one individual sweep with channel activity. With the second method, correction for drift, pick up and microphonics is possible without long periods of minor channel activity. To evaluate the correctness of artifact removal a specific test was set up. The methods were carefully examined using simulated records for a wide range of parameters found in single channel experiments. Further, the developed algorithms were applied to original records obtained from cardiac and recombinant L-type Ca 2+ channels.