Exogenous spermine inhibits ER stress induced by HG. After primary neonatal rat cardiomyocytes were incubated with 40 mmol/L glucose in the presence or absence of spermine (5 μmol/L) for 24 h, ER stress pathway related proteins were detected by western blot. **, P < 0.01 versus Control group; ***, P < 0.001 versus Control group; ##, P < 0.01 versus HG group; ###, P < 0.001 versus HG group.