Separation and analysis of macroscopic currents

In voltage clamp experiments, ionic flow is measured as electrical current. Macroscopic currents recorded from whole cells, or from relatively large areas of cell membrane, represent the sum of the ion fluxes through many channels, generally of more than one type. The first step in the interpretation of such currents is usually their separation into constituent components, each associated with a particular sort of ion channel. This chapter will consider some of the means by which this separation may be achieved, and will also give an introduction to methods for the analysis of the currents isolated in this way.