Live/dead assay
Calcein-AM (C1430; Invitrogen) and propidium
iodide (P4864; Sigma Aldrich) were used to determine the
percentages of viable and dead cells. After the treatments
with melatonin, 106 P19 cells were harvested, washed,
resuspended in HBSS/Ca and loaded with 0.1 μM calcein-
AM and 8 μM propidium iodide for 20 minutes at room
temperature. Fluorescence was measured by FACS
(Becton Dickinson FACScalibur) with 488 nm excitation
wavelength. The simultaneous measurement of Calcein/
propidium iodide fluorescence was performed using
530/30 nm bandpass filter for Calcein and a 610/20 nm
bandpass filter for propidium iodide red fluorescence.
Statistical analyses
Data are mean values ± SEM and multiple comparisons
were carried out using ANOVA followed by the Bonferroni
post hoc test. Significance was accepted with p < 0.05.