Oxidation of intracellular glutathione after exposure of human red blood cells to hypochlorous acid

Abstract

Exposure of human red blood cells to low doses of hypochlorous acid (HOCl) resulted in the loss of intracellular GSH. Oxidation occurred less than 2 min after the addition of HOCl, and required approx. 2.5 mol of HOCl per mol of GSH lost. Loss of GSH preceded oxidation of membrane thiols, the formation of chloramines and haemoglobin oxidation. The susceptibility of intracellular GSH to oxidation by HOCl was two-thirds that of GSH in cell lysates. These results indicate that HOCl can penetrate the red cell membrane, which provides little barrier protection for cytoplasmic components, and that GSH oxidation by HOCl may be a highly selective process. Virtually all of the GSH lost was converted into GSSG. If glucose was added to the medium, most of the GSH oxidized by low doses of HOCl was rapidly regenerated. At higher doses, recovery was less efficient. However, when HOCl was added as a slow infusion rather than in a single bolus, there was increased recovery at higher doses. This indicates that in metabolically active cells regeneration is rapid and GSH may protect cell components from damage by HOCl. HOCl-induced lysis was only slightly delayed by adding glucose to the medium, indicating that lytic injury is not ameliorated by GSH.