Effects of Zn 2+ chelators, DTPA and TPEN, and ZnCl 2 on the cells treated with hydrogen peroxide: a flow-cytometric study using rat thymocytes

Abstract

Recently, we have revealed that trace Zn 2+ partly attenuates Ca 2+ -dependent cell death induced by A23187, a calcium ionophore, in rat thymocytes. In this study, to see if Zn 2+ attenuates the H 2 O 2 -induced cell death that is also Ca 2+ -dependent, the effects of ZnCl 2 and chelators for Zn 2+ have been examined by using a flowcytometer with propidium iodide. The incubation with H 2 O 2 increased the cell lethality. Simultaneous application of ZnCl 2 greatly augmented the H 2 O 2 -induced increase in lethality. DTPA, a chelator for extracellular Zn 2+ , did not affect the increase in cell lethality by H 2 O 2 . However, the H 2 O 2 -induced increase in cell lethality was greatly attenuated by TPEN, a chelator for extracellular and intracellular Zn 2+ . Taken together, it may be likely that intracellular Zn 2+ modifies the H 2 O 2 -induced cytotoxicity. However, it cannot be ruled out the possibility that TPEN chelates intracellular Fe 2+ , resulting in inhibiting the formation of hydroxyl radical from H 2 O 2 that leads to an attenuation of H 2 O 2 cytotoxicity.