PKCα isoform regulated the effect of pyridoxine in ox-LDL-treated HUVECs. (A) Western blot analysis showed the protein expression levels of PKCα in control siRNA or PKCα siRNA. (B, C) The effect of combination treatment of knockdown PKCα, pyridoxine(10−7 mol·L−1) and L-NAME (100 µmol·L−1) on ox-LDL-treated HUVECs and endothelial O2•− production was measured by DHE using flow cytometric (n = 7–10 *P < 0.05 vs. control siRNA, #P < 0.05 vs. ox-LDL, &&P < 0.01 vs. pyridoxine + ox-LDL) and fluorescence microscope. (D) Western blot analysis showed the expression of phosphorylated eNOS Thr495, total-eNOS and β-actin. Phosphorylation was quantified densitometrically as the ratio of p-Thr495-eNOS/total-eNOS (n = 4 *P < 0.05 vs. control siRNA, #P < 0.05 vs. ox-LDL, &P < 0.05 vs. pyridoxine + ox-LDL).