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 ra t isolated fasciculata-reticularis and glomerulosa cells was evaluated by f low cytometry to know the role of these mechanisms in the initiation of cel l injury produced by LPS on adrenocortical cells during endotoxic shock. A rapid increase of intracellular calcium was induced by endotoxin in both ce ll types. In fasciculata-reticularis cells, this [Ca2+](i) increase was mai nly due to an important mobilization of intracellular stores. Dose-dependen t increases in [Ca2+](i) were also observed when both cell types were incub ated with LPS for 20 min in the presence of extracellular calcium. This tre atment abolished the increase in intracellular calcium induced by ACTH and angiotensin II. On the other hand, the endotoxin produced a fast and dose-d ependent increase in reactive oxygen species in both cell types, higher in glomerulosa than in fasciculata-reticularis cells. LPS-pretreated cells sho wed more susceptibility to the oxidative stress induced by Fe2+ These resul ts can be related to functional alterations previously described showing th e involvement of calcium and reactive oxygen species as messengers in the e ndotoxin action on adrenocortical cells. (C) 1999 Elsevier Science B.V. All rights reserved.