Preventing photo-toxicity during calcium imaging. (a) Schematic of OPCs taken from DMEM + SATO based media and MEMO + SOS based media for ratiometric Fura2-AM Ca2+-imaging (λex = 340; 380 nm: UV light) and the representative images acquired at the start, at the end of Ca2+ imaging and in non-imaged areas at the end of experiment. (b) Ratiometric Ca2+ changes in OPCs at the start, after imaging or in non-imaged areas after OPCs were pre-treated in DMEM + SATO (closed histograms) or MEMO + SOS (open histograms) based media. Histograms show means ± s.e.m. of a number of biological replicates (value within or above each histogram) and p-values from Student’s two tailed unequal variance t-test.