[Mitochondrial aldehyde dehydrogenase 2 protects against high glucose-induced injury in neonatal rat cardiomyocytes by regulating CaN-NFAT3 signaling pathway].

OBJECTIVE: To investigate whether CaN-NFAT3 pathway mediates the protective effects of aldehyde dehydrogenase (ALDH) 2 in high glucose-treated neonatal rat ventricular myocytes. METHODS: The ventricular myocytes were isolated from the heart of neonatal (within 3 days) SD rats by enzyme digestion and cultured in the presence of 5-Brdu. After reaching confluence, the cultured ventricular myocytes were identified using immunofluorescence assay for α-SA protein. The cells were then cultured in either normal (5 mmol/L) or high glucose (30 mmol/L) medium in the presence of ALDH2 agonist Alda-1, ALDH 2 inhibitor Daidzin, or Alda-1 and NFAT3 inhibitor (11R-VIVIT). Fluorescent probe and ELISA were used to detect intracellular Ca(2+) concentration and CaN content, respectively; ALDH2, CaN and NFAT3 protein expressions in the cells were detected using Western blotting. RESULTS: Compared with cells cultured in normal glucose, the cells exposed to high glucose showed a significantly decreased expression of ALDH2 protein (P < 0.05) and increased expressions of CaN (P < 0.05) and NFAT3 proteins with also increased intracellular CaN and Ca(2+) concentrations (P < 0.01). Alda-1 treatment significantly lowered Ca(2+) concentration (P < 0.05), intracellular CaN content (P < 0.01), and CaN and NFAT3 protein expressions (P < 0.05), and increased ALDH2 protein expression (P < 0.05) in high glucose- exposed cells; Daidzin treatment significantly increased Ca(2+) concentration (P < 0.01) and intracellular CaN content (P < 0.05) in the exposed cells. Compared with Alda-1 alone, treatment of the high glucose-exposed cells with both Alda-1 and 11R-VIVIT did not produce significant changes in the expression of ALDH2 protein (P>0.05) but significantly reduced the expression of NFAT3 protein (P < 0.05). CONCLUSIONS: Mitochondrial ALDH2 protects neonatal rat cardiomyocytes against high glucose-induced injury possibly by negatively regulating Ca(2+)-CaN-NFAT3 signaling pathway.