APLNR and endothelial dysfunction: In this study, it is revealed that apelin relived diabetic cardiomyopathy (Figs 1 and  2) via increasing angiogenesis (Fig. 4) and decreasing endothelial dysfunction (Figs 3, 5 and  6), which were dependent on endothelial APJ activated NFκB pathway(Figs 7, 8, 9 and  10).