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Article |

Ferric Iron Potentiates Cell Depolarization by a Circulating Shock Protein

Brian J. Eastridge, MD; John A. Evans, PhD; Daniel N. Darlington, PhD; Donald S. Gann, MD
Arch Surg. 1994;129(3):245-251. doi:10.1001/archsurg.1994.01420270021005.
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Objective:  To determine whether or not iron affects the depolarizing activity of a circulating shock protein that appears in plasma after hemorrhage.

Design:  Randomized design.

Setting:  University laboratory.

Animals:  Healthy male Sprague-Dawley rats weighing 300 to 400 g with femoral artery and vein cannulas placed 4 days before hemorrhage.

Intervention:  A 20-mL/kg hemorrhage and plasma collection.

Main Outcome Measures:  Depolarizing activity was measured as the increased fluorescence of an oxonol dye in the presence of Fe3+, Fe2+, or the iron chelator deferoxamine mesylate and was titrated against increasing concentrations of circulating shock protein or iron. Circulating shock protein was derived from plasma and was purified in two steps: stepwise ammonium sulfate precipitation followed by denaturing ion-exchange chromatography and refolding.

Results:  At physiologic concentrations, Fe3+ but not Fe2+ potentiated the depolarizing activity of plasma after ammonium sulfate. Addition of deferoxamine abolished activity. Denaturing chromatography removed nearly all the depolarizing activity; however, Fe3+ restored activity to this fraction. Fe3+ increased total activity and decreased the concentration at which 50% activity was observed.

Conclusion:  These data indicate that physiologic concentrations of Fe3+ may act to modulate the depolarizing activity of circulating shock protein that in turn mediates the intracellular accumulation of salt and water in shock.(Arch Surg. 1994;129:245-251)


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