26 - Patch-Clamp Techniques and Analysis

Abstract

Patch-Clamp Techniques and Analysis This chapter presents an analysis of patch-clamp technique of both macroscopic ionic currents and single ion channels. It is mentioned that the patch-clamp technique revolutionized electrophysiology by revealing the activity of individual molecular ion channels involved in electrical signaling in excitable cells. The chapter first focuses on the technique and its application in studies of single channels or unitary conductances. The chapter also covers the technique of whole-cell "tight-seal" voltage-clamp, an offshoot of the patch-clamp technique that is now the most widely used method of examining membrane excitability. The chapter discusses patch-clamp or Gigaseal technique, single-channel analysis, and whole-cell currents. The patch-clamp was originally devised to measure single-channel currents in an isolated patch of cell membrane. Patch electrodes can make tight stable molecular bonds with membrane surfaces; therefore, the patch-clamp technique can be exploited in a remarkable number of ways to study ion currents at both the single-channel and whole-cell level. Variations of the patch-clamp technique (cell-attached, inside-out, and outside-out) have unique advantages for studying different types of ion-channel gating at the single-channel level. Whole-cell voltage-clamp and its variation, the perforated-patch method, are now probably the most commonly used methods to characterize ionic currents in excitable cells. Whole-cell voltage-clamp and its variation, the perforated-patch method, are now probably the most commonly used methods to characterize ionic currents in excitable cells. The different variations or modes of patch recordings further permit the experimenter to alter the environment and examine the gating and behavior of a single-channel protein. The whole-cell tight-seal voltage-clamp allows experimenters to study a whole world of cells that were previously not accessible to recording with conventional sharp-tipped electrodes. The chapter concludes by stating that a patch-clamp technique can appear for almost any measurement situation, also mentioning a remarkable consequence of the fact that clean glass surfaces can bond to cell membranes.