Recording Currents from Channels and Transporters in Macropatches

This chapter describes methods for the study of ion channels and transporters by recording from membrane macropatches. While investigators have made use of many different cell types for such experiments, we focus here on studies of these proteins expressed exogenously in Xenopus oocytes. We rely on this model system in our laboratory for a number of reasons, including the fact that we are able to obtain seals of very high resistance, typically >150 GΩ. Where possible, we draw comparisons with the study of the same channels by other macroscopic recording techniques; where possible, we also compare results from macropatch experiments with results of similar experiments using single-channel recording. We provide examples of experiments with the following proteins: the human cystic fibrosis transmembrane conductance regulator (CFTR), the rabbit ClC-2 voltage-gated chloride channel, and a Na⁺ /Ca²⁺ exchanger from Drosophila melanogaster (Calx1.2).