ABC | Volume 110, Nº1, January 2018

Original Article Hu et al Melatonin’s modulation on calcium in cardiomyocytes Arq Bras Cardiol. 2018; 110(1):44-51 Figure 5 – Melatonin modulated expression of SERCA2a and IP3R in H9C2 cells against H/R via ERK1 pathway in vitro. The results indicated melatonin inhibited expression of IP3R and promoted expression of SERCA2a which was reduced by PD98059. Representative Western blot images (A) and quantitative analysis (B-C) showed melatonin’s effect on expression of IP3R and SERCA2a via ERK1 pathway in H9C2 cells against H/R.bar = 30 μm. **p < 0.01 vs. control group; Sp < 0.05 vs. H/R group; #p < 0.05 vs. H/R+Mel group. (Control: control group; H/R:H/R group; H/R+mel: H/R+ melatonin group; H/R+mel+PD: H/R+ melatonin+PD98059 group) Control Control H/R H/R H/R+Mel H/R+Mel H/R+Mel+PD H/R+Mel+PD Control H/R H/R+Mel H/R+Mel+PD IP3R SERCA2a β-actin ** ** S S # # IP3R expression levels (Relative density) SERCA2a expression levels (Relative density) A B 2.5 2.0 1.5 1.0 0.5 0 1.00 0.75 0.50 0.25 0 Figure.6 – Melatonin modulated expression of IP3R and SERCA2a via ERK1 pathway in reperfused rat hearts. In reperfused myocardium, expression of IP3R and SERCA2a were assessed by immunofluorescence staining (A) and quantitative analysis (B-C). The results showed that fluorescence intensity of IP3R was increased in I/R group more than in control group, but was lower in melatonin group compared with I/R group. On the contrary, melatonin increased expression of SERCA2a in reperfused myocardium. Both of the effects of melatonin on expression of IP3R and SERCA2a were inhibited by PD98059 (ERK1 inhibitor). bar = 30 μm. All values are presented as the mean ± SD. n = 5.*p < 0.05 vs. control group; Sp < 0.05 vs. I/R group; #p < 0.05 vs. I/R+Mel group. (Control: control group; I/R:I/R group; I/R+mel: I/R+ melatonin group; I/R+mel+PD: I/R+ melatonin+PD98059 group). Control Control I/R I/R I/R+Mel I/R+Mel I/R+Mel+PD Control I/R I/R+Mel I/R+Mel+PD I/R+Mel+PD IP3R SERCA2a Merge * S # * S # Expression of IP3R (Relative fold) Expression of SERCA2a (Relative fold) A B C 6 5 4 3 2 0 1 6 5 4 3 2 0 1 on apoptosis, F-actin organization and calcium overload in cardiomyocytes against H/R. To further elucidate the underlying mechanism for protective effect of melatonin cardiomyocytes against H/R, we observed the effects of melatonin on expression of IP3R and SERCA2a. The results showed SERCA2a expression is decreased in H/R group compared with control group, but melatonin promoted SERCA2a expression in cardiomyocytes. Contrarily, H/R induces IP3R expression, and melatonin inhibits 49