Which of the following technique is used to study current flow across a single ion channel?

Ans. a. Patch clamp (Ref: Ganong 24/e p49; http://en.wikipedia.org/wiki/Patch_clamp)Patch clamp is used to study current flow across a single ion channel.'The patch clamp technique is a laboratory technique in electrophysiology that allows the study of single or multiple ion channels in cells. The technique can be applied to a wide variety of cells, but is especially useful in the study of excitable cells such as neurons, cardiomyocytes, muscle fibers and pancreatic beta cells. It can also be applied to the study of bacterial ion channels in specially prepared giant spheroplasts.'- http://en.wikipedia.org/wiki/ Patch clampPatch Clamp TechniqueThe patch clamp technique is a laboratory technique in electrophysiology that allows the study of single or multiple ion channels in cells.The technique can be applied to a wide variety of cells, but is especially useful in the study of excitable cells such as neurons, cardiomyocytes, muscle fibers and pancreatic beta cells.It can also be applied to the study of bacterial ion channels in specially prepared giant spheroplasts.The patch clamp technique is a refinement of the voltage clamp.Erwin Neher and Bert Sakmann developed the patch clamp in the late 1970s and early 1980s.This discovery made it possible to record the currents of single ion channels for the first time, proving their involvement in fundamental cell processes such as action potential conduction.In this technique a micropipette is placed on the membrane of a cell and form a tight seal to the membrane.The patch of membrane under the pipette tip usually contains only a few transport proteins, allowing for their detailed biophysical study.The cell can be left intact (cell-attached patch clamp). Alternatively, the patch can be pulled loose from the cell, forming an inside out patch.A third alternative is to suck out the patch with the micropipette still attached to the rest of the cell membrane, providing direct access to the interior of the cell (whole cell recording).