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Population Patch Clamp Technology

Biological variability (i.e., cell health, cell size, and channel expression levels) is the major contributing factor for reduced success rates in planar patch clamp systems. To compensate, the IonWorks® HT system was initially designed to increase the likelihood of obtaining at least one successful recording for every compound by assaying compounds in quadruplicates. Thus the probability of obtaining at least one recording for every compound using a cell line with 70% success rate is 99.2%; but at the expense of lower throughput. A four-fold increase in throughput could be immediately realized in the IonWorks HT system by eliminating the quadruplicates. To achieve this objective, Molecular Devices developed Population Patch Clamp™ (PPC) technology1,2, a revolutionary approach that records averaged ionic currents from a population of up to 64 cells expressing a recombinant voltage-gated ion channel. Cells are plated into a 384-well PatchPlate™ PPC substrate in which each well containing 64 recording sites as depicted below showing 5 of the 64 wells.

Consistency and Data Quality: PPC provides better data consistency and data quality because ionic currents are measured from a population of cells.  The average current measured during experiments on the IonWorks® Quattro system is highly consistent from one well to the next. The measured currents on the IonWorks Quattro system have significantly reduced coefficient of variation values. The %CV for Kv1.3 currents is 8% versus 34% for the IonWorks Quattro and IonWorks HT systems, respectively; for Nav1.5 currents, 18% versus 44%, respectively; and for hERG currents, 28% versus 50%, respectively. Raw data traces from PPC recordings are shown below.

Success rates are so high (above 95%) that it is not necessary to apply test compounds redundantly to four wells, thereby enabling an immediate four-fold throughput improvement over the first-generation IonWorks HT system.

References:

[1] http://www.ncbi.nlm.nih.gov/pubmed/16760372?dopt=Citation

[2] http://www.ncbi.nlm.nih.gov/pubmed/17882333?dopt=Citation