Analysis of ATP-Induced Ca²⁺ Responses at Single Cell Level in Retinal Pigment Epithelium Monolayers

Calcium is one of the most important second messengers in cells and thus involved in a variety of physiological processes. In retinal pigment epithelium (RPE), Ca²⁺ and its ATP-dependent signaling pathways play important roles in the retina maintenance functions. Changes in intracellular Ca²⁺ concentration can be measured from living cells by Ca²⁺ imaging. Combining these measurements with quantitative analysis of Ca²⁺ response properties enables studies of signaling pathways affecting RPE functions. However, robust tools for response analysis from large cell populations are lacking. We developed MATLAB-based analysis tools for single cell level Ca²⁺ response data recorded from large fields of intact RPE monolayers. The analysis revealed significant heterogeneity in ATP-induced Ca²⁺ responses inside cell populations regarding magnitude and response kinetics. Further analysis including response grouping and parameter correlations allowed us to characterize the populations at the level of single cells.