Patch Clamping

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The Patch Clamping Technique was introduced by Erwin Neher and Bert Sakmann in 1976. It is an in vitro, electrophysiological technique which allows you to study either a single ion channel in a cell or the all of the ion channels in the cell membrane, depending on the configuration of the cell. This techniques allows you to measure the currents flowing through one ion channel or the sum of all the currents flowing through all the ion channels in a cell membrane. The technique involves using a blunt glass pipette, 1-2 microns in width and trapping a patch of the cell membrane with the glass pipette. The ion channel associated with that patch of membrane is now also trapped. Inside the glass pipette there is an ionic solution and the cell is surrounded by a bath solution. There is a strong seal between the glass pipette and the patch of membrane, a Giga Ohm seal (109 Ohms) (gigaseal which allows the patch of membrane to be isolated from the rest of the cell membrane [1]. A known voltage can then be applied across the membrane and the current can be measure accurately due to the gigaseal. 

There are three types of clamping techniques:

  1. On-cell patch which measures indirect effect of extracellular solutes on channels withing membrane patch on intact cell. 
  2. Inside-out deatached patch measures efftects of intracellular solutes on channels within isolated patch.  
  3. Outside-out detached patch measures effects of extracellular solutes on channels within isolated patches [2][3].

References

  1. Alberts B. et al. (2008), Molecular Biology of the Cell, Fifth Edition page 681, Garland Science, Taylor and Francis Group, LLC, New York, USA
  2. Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 7th edition. New York: W. H. Freeman; 2013, Page 500
  3. Jeremy M B, John L T, Lubert S, et al. Biochemistry. 7th edition. New York: W. H. Freeman; 2012, page 383
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