The effect of exogenous H2S on the cell viability and apoptosis in the d-galactose age-induced primary cultured neonatal cardiomyocytes. a Cell viability was measured by MTT assay. The cells incubated with control medium were considered 100% viable. b Apoptosis analyzed by flow cytometry. c Detection of nuclear morphology in apoptotic cells by Hoechst 33342 staining. Apoptotic cells were identified as cells with condensed, disrupted nuclei (arrow, Hoechst staining, ×400). Scale bar 100 μm. Apoptotic cells in at least five random fields were counted. All data were from four independent experiments. *p < 0.05 vs. control group; #p < 0.05 vs. H/R group; &p < 0.05 vs. PC group; $p < 0.05 vs. H/R + NaHS group.