Ion channel dysfunctions lead to a wide array of illnesses including epilepsy, cardiac arrhythmia and type II diabetes. However, the number of clinically approved drugs for restoring normal ion channel function is limited. A major bottleneck for the development of new ion channel drugs is that present screening methodologies are primarily based on patch clamping, a powerful, but time consuming technique that only allows examination of only a handful of compounds a day. Stanford University scientists have developed a concept system for high-throughput screening of ion channel drugs using optical stimulation and fluorescent read-out.
In this system, light of the proper wavelength is cast upon the optically-gated cells in each well in the presence of a novel compound, the cells will react or fail to react to the light, based upon the drugs' properties. To create this system, a light sensitive ion channel (e.g.
Chlamydomonas channelrhodopsin-2 and
Volvox channelrhodopsin-1) and a voltage-gated Ca2+ channel are co-expressed in 293T cells. Upon illumination with the appropriate wavelength of light, light-mediated depolarization activates the co-expressed voltage-gated Ca2+ channels. The subsequent activity of Ca2+ channel in the presence of different small molecules is the optically monitored using either a fluorescent indicator dye (i.e. Fura-2) or genetically encoded activity sensor. The fluorescence signal is recorded via time-lapse imaging for later analysis.
