Electrophysiological Methods for the Study of TRP Channels

Transient receptor potential (TRP) cation channels function as polymodal cellular sensors involved in the fine-tuning of many physiological processes.– Intriguingly, mutations in the encoding genes cause a plethora of diseases, and TRP channels are considered, to date, the most attractive channel targets by the pharmaceutical industry. This exploding interest in TRP channels makes it necessary to revisit some of the elementary methods and tools to describe these proteins as what they are, ion channels. Without any doubt, the most direct way to approach function of ion channels is the use of patch-clamp methods. Here we give a short description of how those methods can be used to evaluate gating properties, pore and permeation properties, selectivity sequences of TRP channel pores, and the measurement of fractional Ca2+ currents, i.e., the determination of the percentage of a current carried by Ca2+ as charge carrier. We also include some description of methods, which enable a researcher to obtain information about the pore structure, e.g., sizing of the pore, and discuss some modeling approaches used for determination of gating schemes. It is to be noted, however, that we do not intend by any means to supplant the role of more extensive treatises on ion channel and membrane biophysics,– to which we keenly refer the reader.