Calcium and reactive oxygen species as messengers in endotoxin action on adrenocortical cells

The effect of Escherichia coli 0111:B4 endotoxin (lipopolysaccharide, LPS) on the intracellular Ca2+ and reactive oxygen metabolite content of both rat isolated fasciculata-reticularis and glomerulosa cells was evaluated by flow cytometry to know the role of these mechanisms in the initiation of cell injury produced by LPS on adrenocortical cells during endotoxic shock. A rapid increase of intracellular calcium was induced by endotoxin in both cell types. In fasciculata-reticularis cells, this [Ca2+]i increase was mainly due to an important mobilization of intracellular stores. Dose-dependent increases in [Ca2+]i were also observed when both cell types were incubated with LPS for 20 min in the presence of extracellular calcium. This treatment abolished the increase in intracellular calcium induced by ACTH and angiotensin II. On the other hand, the endotoxin produced a fast and dose-dependent increase in reactive oxygen species in both cell types, higher in glomerulosa than in fasciculata-reticularis cells. LPS-pretreated cells showed more susceptibility to the oxidative stress induced by Fe2+. These results can be related to functional alterations previously described showing the involvement of calcium and reactive oxygen species as messengers in the endotoxin action on adrenocortical cells.