Figure 17 Dose-response curve for Jurkat cells transfected with a β-lactamase reporter gene and stimulated with carbachol. The emission intensity ratio at 460–520 nm was normalized by the sensitization ratio obtained at 10− M agonist concentration. See color plate.

Further utility of the miniaturized assay is provided by a different set of transformed Jurkat cells that are activated by carbachol and provide a convenient cell-based assay for screening chemical compounds for possible effect on signal transduction processes mediated by muscarinic receptors and heterotrimeric G-proteins (in addition to NFAT and NFKB-activated gene transcription). In Figure 18, the results of screening 100,000 compounds in 30-NanoWell plates are summarized by the extent to which test compound can overcome pirenzepine-mediated inhibition of carbachol-stimulated green-to-blue conversion. In these experiments, about 1-10 pmol of each test compound was added to each well in a NanoWell assay plate with the PSDR. The compounds were added to the seeded cells and incubated for 6 h, then the cells were stimulated with carbachol in the presence of pirenzepine and processed for assessment of β-lactamase activation.