Flow Cytometric Analysis of the H2O2-Induced Increase in Intracellular Ca2+ Concentration of Rat Thymocytes

Abstract

The effect of hydrogen peroxide (H202) on the intracellular Ca2+ concentration ([Ca 2+]i) of

Mechanism of Resistance to Oxidative Stress in Doxorubicin Resistant Cells.

“…These findings suggest that the intracellular Ca 2ϩ is not involved directly in hydrogen peroxide (1 mM)-induced cell death in the resistant cells. Okazaki et al 35) showed that hydrogen peroxide may increase the [Ca 2ϩ ] i through a mechanism related to the effects of hydrogen peroxide on the cellular nonprotein thiol. Accordingly, the elevated level of intracellular GSH in the resistant cells seems to reduce the amount of hydrogen peroxide-induced increase in the intracellular Ca 2ϩ .…”

New Curcuminoids Isolated from Zingiber cassumunar Protect Cells Suffering from Oxidative Stress: A Flow-Cytometric Study Using Rat Thymocytes and H2O2

“…However, as shown in Figs. 3 and 9, the application of 3 mM H202 to the cells also increases [Ca 2+], (4). The sus tained increase in [Ca 2+1, is one of common features in the processes leading to cell death and cell injury (19)(20)(21)(22)(23)(24)(25).…”

“…However, there is no information concerning their protective actions on living cells suffering from the oxidative stress. In this study, we first examined the effects of cassumunins A and B on living cells under oxi dative stress induced by hydrogen peroxide (H202) by using a flow cytometer and ethidium bromide (3)(4)(5) to determine if they exert protective actions on living cells. Secondly, we have compared the potencies of cassumu nins in protecting the cells against the oxidative stress with that of curcumin because curcumin, a compound abun dant in ginger rhizomes, is known to have antioxidant activity (6,7) and its chemical structure is contained in those of cassumunins A and B (see Fig.…”

“…Ethidium bromide was added into the cell suspension to achieve a final concentration of 10 pM. Ethidium, which is highly impermeant to intact membrane, can not stain live cells while it can stain dead or damaged thymocytes because of their compromised membranes (3,4,8). Therefore, the measurement of ethidium fluorescence from thymocytes provides a clue to estimate the viability of thymocytes in the cell suspension.…”

“…3). However, it was likely that H202 at 3 to 10 mM was lethal for thymocytes during exposure lasting for 2 hr or longer (3,4) since the prolonged exposure of thymocytes to 3 mM or 10 mM H202 produced a time dependent increase in the number of thymocytes stained with ethidium, indicating a time-dependent decrease in the number of intact cells (Figs. 3 and 4).…”