Alteration in the radiation-induced LD release in HeLa cells by acyclovir

The aim of the present investigation was to study the effect of various concentrations of acyclovir (ACV) alone or the effect of 0.1 micromol/l acycloir pretreatment on the radion-induced lactate dehydrogenase (LD) release by HeLa cells exposed to 0-3 Gy of gamma-radiation. The plateau-phase cells were treated with 0-100 micromol/l ACV for 8 h or 0.1 micromol/l ACV before exposure to 0-3 Gy of gamma-radiation. The whole media was removed from the culture and the LD release was measured at 0, 0.5, 1, 2, and 4 h post-drug treatment or post-irradiation. The ACV treatment resulted in a concentration-dependent elevation in the LD release at all the post-treatment time periods. A peak level for LD release was observed at 0 h up to 1 micromol/l ACV and declined thereafter. However, at higher doses a highest elevation in LD release was observed at 1 h post-treatment. Pretreatment of HeLa cells with 0.1 micromol/l ACV before irradiation to different doses of gamma-radiation resulted in significant elevation in the release of LD in the medium. The LD release was twofold greater in the ACV+irradiation group at 0 h post-irridiation when compared with the concurrent PBS+gamma-radiation group. The highest increase in LD activity was observed at 0 h post-irradiation and a gradual decline thereafter, without restoration to non-drug treated control level up to 4 h post-irradiation. The LD measurements can serve as a short-term assay to evaluate the cytotoxicity of ACV or radiation in vitro.