Store-operated Ca2+ entry (SOCE) pathway plays important roles in many cellular processes, which is largely studied by using fluorescent Ca2+ indicator, Fura-2. Extracellular Mn2+ is able to cross the plasma membrane through SOCE and quenches the fluorescence signals from Fura-2. Thus, the fluorescence quenching rate by Mn2+ composes a convenient assay to monitor the extent of SOCE. This chapter describes an experimental method of Mn2+ quenching assay for both cultured esophageal epithelial and skeletal muscle cells. It also explains how to perform a quantitative analysis of graded SOCE.
Keywords: Esophageal squamous cell carcinoma; Fura-2-AM; Isosbestic point; Mn2+ quenching; Ratiometric dye; Skeletal muscle myotube; Store-operated Ca2+ entry.