Cell death and lipid peroxidation in isolated hepatocytes incubated in the presence of hydrogen peroxide and iron salts

Abstract

The incubation of isolated hepatocytes in the presence of glucose plus glucose oxidase, a H2O2-generating system, resulted in extensive loss of cell viability, as expressed by the release of lactate dehydrogenase (LDH). Disturbance of metabolic functions such as glycogen and protein synthesis was also caused by H2O2, but in no case was malondialdehyde (MDA)-like products detected. The lytic effect of H2O2 was significantly enhanced by incubating hepatocytes in the presence of iron salts. Under these conditions, MDA-like products were detected, but lipid peroxidation and cell injury did not correlate. Iron chelators modulated the cytotoxicity of H2O2 in different (and opposite) ways: when iron was complexed with ADP, increased cell lysis was observed compared to uncomplexed iron plus H2O2. Iron-DTPA, on the contrary, decreased such a lytic effect. The preincubation of hepatocytes with desferrioxamine mesylate (Desferal; a strong iron chelator) abolished the cytolytic effects produced by the association of iron salts and H2O2, as well as the membrane oxidative injury due to H2O2 alone, thus suggesting the existence of an intracellular source of iron. This kind of mechanism (metal chelation rather than radical scavenging) is supported by the absence of any protective effect by some free radical scavengers against the oxidative injury induced by the association iron H2O2. Nevertheless, the glycogenolytic effects observed in the presence of H2O2 were not modified by Desferal. In our opinion, the cytotoxicity of the association H2O2 plus iron salts involves at least two different and independent mechanisms.

Effects of Extracellular ATP on Fe2+‐Induced Cytotoxicity in PC‐12 Cells

“…EXTRACELLULAR ATP AND PC-12 CELL DEATH DISCUSSION 899 Iron has been reported to cause cell death in both neuronal and nonneuronal cells (Latour et al, 1992;Michel et al, 1992). In a similar way, our studies show that 24-48-h incubation of PC-12 cells with iron leads to cell lysis in a concentration-dependent manner (Fig .…”

Nutrient Deprivation of Cultured Rat Hepatocytes Increases the Desferrioxamine-available Iron Pool and Augments the Sensitivity to Hydrogen Peroxide

“…Most importantly, hydrogen peroxide is a potential source of one of the most dangerous radical known, the hydroxyl radical, through the Fenton reaction. This study, and several others, have lately shown that increase of cellular iron content obtained by exposing cell cultures to Fe 3ϩ will lead to a higher probability for hydroxyl radical formation and, thus, increased oxidative damage (12,37). Conversion of intracellular iron to a more redox active form would result in increased risk of oxidative damage (8,26,38).…”

“…The importance of catalytically active iron in oxidative stress-induced cell killing has been shown in several studies (9,10). Addition of the strong iron chelator, desferrioxamine (DFX), 1 protected against the oxidative damage induced by hydrogen peroxide (11)(12)(13) and redox cycling compounds (14).…”

?Free? iron, as detected by electron paramagnetic resonance spectroscopy, increases unequally in different tissues during dietary iron overload in the rat

“…The addition of Desferal consistently inhibits free radical processes induced by the addition of exogenous iron, or following the release of 'free' iron from transport or storage proteins (Miller et al 1992, Latour et al 1992, Fantini & Yoshioka 1993.…”