Figure 7. Alda-1 decreased ALDH2 O-GlcNAc modification and improved myocardial ischemia/reperfusion injury exacerbated by hyperglycemia.

A. ALDH2 dehydrogenase activity in Con, HG, HG+H/R, HG+H/R+Alda-1 groups in vitro. ALDH2 activity was determined by measuring the conversion of NAD⁺ to NADH. B. ALDH2 O-GlcNAcylation in Con, HG, HG+H/R, HG+H/R+Alda-1 groups in vitro. Cell lysates were immunoprecipitated with specific anti-ALDH2 antibody and then subjected to western blot using anti-O-GlcNAc (CDT110.6) antibody. C. ALDH2 O-GlcNAcylation in Sham, DM, DM+I/R, DM+I/R+Alda-1 groups in rats. D. LVEDP, LVESP, +LVdp/dt_max and -LVdp/dt_max in Sham, NS+I/R, DM+I/R, DM+I/R+Alda-1 groups in rats. LVEDP: left ventricular end diastolic pressure; LVESP: left ventricular end systolic pressure; +LVdp/dtmax, left ventricular maximal rate of pressure increase; -LVdp/dt_max, left ventricular maximal rate of pressure decrease. E. Left: representative photographs of heart sections stained by 2, 3, 5-triphenyltetrazolium (TTC) in Sham, NS+I/R, DM+I/R, DM+I/R+Alda-1 groups in rats; Right: myocardial infarct size expressed as percentage of the total left ventricular area. F. Left: representative photographs of in situ detection of apoptotic myocytes by TUNEL staining in Sham, NS+I/R, DM+I/R, DM+I/R+Alda-1 groups in rats; Right: percentage of TUNEL-positive nuclei in heart tissue sections. Scale bar, 50μm. Mannitol was used to keep the osmolarity consistent among different glucose concentrations in vitro. In A-C graphs, the mean value of Con or Sham was expressed as 1 or 100%. Con: normal glucose; HG: high glucose; H/R: hypoxia/reoxygenation; Alda-1: a specific ALDH2 activator; Sham, sham-operated; DM, diabetes; I/R, myocardial ischemia/reperfusion. Data are means ± SEM of 4 to 8 samples in each group. *P<0.05 vs Con or Sham group, †P<0.05 vs HG or DM group, ‡P<0.05 vs HG+H/R+Alda-1 or DM+I/R+Alda-1 group, §P<0.05 vs NS+I/R group, ‖P<0.05 vs DM+I/R group.