RESEARCH ARTICLE High-Throughput Screening of Myometrial Calcium-Mobilization to Identify Modulators

The uterine myometrium (UT-myo) is a therapeutic target for preterm labor, labor induc-tion, and postpartum hemorrhage. Stimulation of intracellular Ca2+-release in UT-myo cells by oxytocin is a final pathway controlling myometrial contractions. The goal of this study was to develop a dual-addition assay for high-throughput screening of small molec-ular compounds, which could regulate Ca2+-mobilization in UT-myo cells, and hence, myometrial contractions. Primary murine UT-myo cells in 384-well plates were loaded with a Ca2+-sensitive fluorescent probe, and then screened for inducers of Ca2+-mobiliza-tion and inhibitors of oxytocin-induced Ca2+-mobilization. The assay exhibited robust screening statistics (Z ´ = 0.73), DMSO-tolerance, and was validated for high-throughput screening against 2,727 small molecules from the Spectrum, NIH Clinical I and II collec-tions of well-annotated compounds. The screen revealed a hit-rate of 1.80 % for agonist and 1.39 % for antagonist compounds. Concentration-dependent responses of hit-com-pounds demonstrated an EC50 less than 10μM for 21 hit-antagonist compounds, com