Use of escin as a perforating agent on the IonWorks quattro automated electrophysiology platform

The automated electrophysiology platform IonWorks has facilitated the medium-throughput study of ion channel biology and pharmacology. Electrical and chemical access to the cell is by perforated patch, afforded by amphotericin. Permeation of the amphotericin pore is limited to monovalent cations. We describe here the use of the saponin escin as an alternative perforating agent. With respect to the number and robustness of seals formed across a variety of cell and ion channel types, the performance of escin is equal to that of amphotericin. Escin also permits the permeation of larger molecules through its pore. These include nucleotides, important intracellular modulators of ion channel activity that can be used to prevent ion channel rundown of, for instance, Ca(V)1.2. Furthermore, pharmacologic agents such as QX314 can also permeate and be used for mechanistic studies. Escin, in combination with IonWorks, increases the scope of ion channel screening and can facilitate the assay of previously difficult-to-assay targets.