Cellular Functions in Glutathione-Depleted Hepatocytes

Summary

These studies were performed under the general hypothesis that glutathione (GSH) deficiency per se is not compatible with cell survival. Isolated hepatocytes were incubated with halogenated acetamides to deplete the GSH pool. The selectivity of the GSH depletion was increased by incubating at zero instead of at 37°C and after 1 h more than 50 nmol GSH was lost and less than 0.5 nmol acetamide/10⁶ cells was co-valently bound to cellular macromolecules. Upon continued incubation (at 37°C) in an amino acid-free medium (under these conditions the rate of GSH replenishment was absent or very low) the cells eventually lysed. A first stage of cell deterioration was detected as an inability of the cells to utilize methionine for GSH synthesis when this amino acid was added to the medium. A second stage was characterized by an accumulation of malondialdehyde in the cells, indicating an increase in the extent of lipid peroxidation. During a third stage the cells lysed. This sequence of events could be prevented by methionine when added prior to the first state or by cysteine when added prior to or during the first stage. The antioxidant α-tocopherol also prevented cell damage. The possibility that the impaired methionine utilization is a “point of no return” in a sequence which starts with GSH depletion and ends in cellular necrosis is discussed.

Supported by grants from Kardinska Institutet (No. 390–5) and Arbetarskyddsfonden (No. 77–295).