In this study, a novel approach to measure the absolute cytoplasmic Ca^(2+) concentration([Ca^(2+) ]cyt) using the Ca^(2+) indicator fluo-3 AM was established. The parameters associated with the probe fluo-3 AM were optimized to accurately determine fluorescence intensity from the Ca^(2+) -bound probe. Using three optimized parameters(final concentration of 6 m M probe,incubation time of 135 min, loading probe before plasma treatment), the maximum fluorescence intensity(F_(max)?=?527.8 a.u.) and the minimum fluorescence intensity(F_(min)?=?63.8 a.u.) were obtained in a saturated Ca^(2+) solution or a solution of lacking Ca^(2+) . Correspondingly, the maximum [Ca^(2+) ]cytinduced by cold plasma was 1232.5 n M. Therefore, the Ca^(2+) indicator fluo-3 AM was successfully applied to measure the absolute [Ca^(2+) ]cytin Saccharomyces cerevisiae stimulated by cold plasma at atmospheric air pressure.
