Ionic channels, patch-clamp recording

Figure 5. The four-patch clamp recording methods. In each example, the cell is shown to the left, the micropipette to the right. For a discussion of the methods see text. Reproduced with permission from Hille, B., "Ionic channels of excitable membranes" 1 st ed., Sinauer, Sunderland, MA (1984) p. 217.

The patch-clamp technique is based on the formation of a high resistance seal (109-10lon) between the tip of a glass micropipette and the cell membrane it touches (gigaohm-seal). This technique allows recordings of ionic currents through single ion channels in the intact cell membrane and in isolated membrane patches at a... 

Figure 1 Schematic diagrams illustrating the patch-clamp technique. (A) Overall setup for isolating single ionic channels in an intact patch of cell membrane. P = patch pipet R = reference microelectrode I = intracellular microelectrode Vp = applied patch potential Em = membrane potential Vm = Em — Vp = potential across the patch A = patch-clamp amplifier. (From Ref. 90.) (B) Five different recording configurations, and procedures used to establish them, (i) Cell attached or intact patch (ii) open cell attached patch (iii) whole cell recording (iv) excised outside-out patch (v) excised inside-out patch. Key i = inside of the cell o = outside of the cell. (Adapted from Ref. 283.)...

Readers who want to have an extended theoretical background on the properties of ionic channels are referred to the textbook Ionic Channels of Excitable Membranes by Hille [5]. More details on the patch-clamp technique are described in the book Single Channel Recording by Sak-mann and Neher [4]. 

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