Macrolides are clinically well-established class of antibiotics. Macrolides
induce cardiotoxicity by blocking ether-a-go-go–related gene
(ERG) potassium channels in cardiac myocytes. The aim of this study was to
compare the effects of erythromycin, clarithromycin and azithromycin on cell
viability and expression of ERG1 gene in H9c2 cells. Cell viability and ERG1
gene expression of H9c2 cells in 3 different concentrations, 1, 10 and
25 µg/ml, after 48 and 72 h were determined by
MTT test and Real time-PCR method respectively. After 48 h, the growth
of H9c2 cells treated with erythromycin, clarithromycin and Azithromycin (except
two doses) were inhibited significantly compared to control group
(p<0.05). All three groups of antibiotics showed toxic effects on cells
after 72 h in all concentrations. Azithromycin-inhibiting effects were
significantly higher than two other groups after 72 h of treatment. The
expression of ERG1 gene increased in all three groups of antibiotics by
increasing the concentration and duration of treatment. Azithromycin had the
most pronounced effect on ERG1 expression in 48 and 72 h. This study
indicated that these macrolides affect ERG1 expression due to their potential
cardiac adverse effects. Further investigations are required to understand the
exact mechanism of cardiotoxicity associated with macrolides.