title: Application of ion-sensitive field effect transistors for ion channel screening.
abstract: Cell-based screening assays are now widely used for identifying compounds that serve as ion channel modulators. However, instrumentation for the automated, real-time analysis of ion flux from clonal and primary cells is lacking. This study describes the initial development of an ion-sensitive field effect transistor (ISFET)-based screening assay for the acquisition of K(+) efflux data from cells cultured in multi-well plates. Silicon-based K(+)-sensitive ISFETs were tested for their electrical response to varying concentrations of KCl and were found to display a linear response relationship to KCl in the range of 10 µM-1 mM. The ISFETs, along with reference electrodes, were inserted into fast-flow chambers containing either human colonic T84 epithelial cells or U251-MG glioma cells. Application of the Ca(2+) ionophore A23187 (1 µM), to activate Ca(2+)-activated non-selective cation (NSC) channels (T84 cells) and large conductance Ca(2+)-activated K(+) (BK) channels (U251 cells), resulted in time-dependent increases in the extracellular K(+) concentration ([K(+)]o) as measured with the ISFETs. Treatment of the cells with blockers of either the NSC or BK channels, caused a strong inhibition of the A23187-induced increase in [K(+)]o. These results were consistent with ion current measurements obtained using the whole-cell arrangement of the patch clamp procedure. In addition, K(+) efflux data could be acquired in parallel from multiple cell chambers using the ISFET sensors. Given the non-invasive properties of the probes, the ISFET-based assay should be adaptable for screening ion channels in various cell types.
authors: Department of Pharmacology, Physiology & Neuroscience, University of South Carolina, School of Medicine, Columbia, SC 29209, USA. Electronic address: walsh@uscmed.sc.edu.
authors: Kenneth B
authors: KB
authors: Walsh
authors: Department of Electrical Engineering, University of South Carolina, School of Engineering, Columbia, SC 29208, USA.
authors: Nicholas
authors: N
authors: DeRoller
authors: Department of Electrical Engineering, University of South Carolina, School of Engineering, Columbia, SC 29208, USA.
authors: Yihao
authors: Y
authors: Zhu
authors: Department of Electrical Engineering, University of South Carolina, School of Engineering, Columbia, SC 29208, USA.
authors: Goutam
authors: G
authors: Koley
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation*; D002460:Cell Line; D004867:Equipment Design; D006801:Humans; D007473:Ion Channels / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D014173:Transistors, Electronic
chemical_list: D007473:Ion Channels; D011188:Potassium
keywords: Cell lines; ISFET; Ion channel modulators; K(+) efflux; Screening assay