Figure 4. Apigenin decreases CD38 expression, and increases Sirt3 activity and NAD+/NADH ratio in renal proximal tubular cells grown in high glucose. (A) Western blots of CD38, Sirt3, ace (Lys413)-IDH2, IDH2, ace (Lys68)-SOD2, SOD2, and β-actin in HK-2 cells cultured in low glucose (LG; 5.55 mM) or high glucose (HG; 25 mM), with and without 10 μM apigenin. (B–E) Densitometric evaluation of CD38 to β-actin (B), Sirt3 to β-actin (C), Ace-IDH2 to IDH2 (D), and Ace-SOD2 to SOD2 (E) immunoblotting data shown in panel A (n=4). (F) Intracellular NAD+/NADH ratio in cultured HK-2 cells (n=4). All data represent the mean ± standard deviation (SD). *p<0.01 vs. the indicated group, **p<0.05 vs. the indicated group, n.s; not significant.