Effects of zinc on cell viability and glucose consumption of insulin-resistant cells

Objective To elucidate the effects of zinc on cell viability and glucose consumption of insulin-resistant cells.Methods After the establishment of insulin-resistant cell model,the HepG2,3T3-L1,and L6 cells of the models were exposed to different doses of zinc(0,20,50,100,200,and 400 μmol/L) for 3 hours; then cell viability was determined with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H- tetrazolium bromide(MTT) assay and glucose consumption was detected with glucose oxidase method.Results After 3 hours' incubation with high concentration of zinc(200 and 400 μmol/L),cell viability was down-regulated significantly(P< 0.05).Zinc at the concentrations of 50-100 μmol/L could increase glucose consumption of HepG2 and 3T3-L1 cells in both normal and insulin-resistant state; however,the effect was weaker than that of insulin.Compared with insulin or 100 μmol/L zinc treatment alone,the combined treatment of the two agents showed stronger effect(P< 0.05).For L6 myotubes,zinc at the concentrations of 20-100 μmol/L showed stimulatory effect in both normal and insulin-resistant cells(P< 0.05) and an enhanced effect was observed when zinc at 20 μmol/L combined with insulin in comparison with insulin or zinc treatment alone(P< 0.05).Conclusion Zinc at certain doses plays a promotive role in glucose consumption of HepG2,3T3-L1,and L6 insulin-resistant cells,but its effective dose is different among the three cell lines.