The influence of glutathione depleting agents on human platelet function

Human platelets were dose- and time-dependently depleted of intracellular glutathione (GSH) by treatment with the chemical oxidizing agents diamide and N-ethylmaleimide (NEM), and by formation of chemical conjugates with 1-chloro-2,4-dinitrobenzene (CDNB) catalyzed by GSH-S-transferase. In addition to effects upon GSH, these agents also inhibited platelet GSH-peroxidase activity. The inhibitory effect of CDNB was selective for GSH-peroxidase, while diamide and NEM treatment caused inhibition of several other cytosolic enzymes tested. Arachidonic acid (AA) induced aggregation and secretion responses measured in platelets depleted of GSH by diamide and NEM were attenuated. In contrast, these platelet functions remained identical to control following GSH depletion by CDNB treatment, suggesting that GSH is not required for normal platelet aggregation or secretion. Effects of diamide and NEM apart from their action on GSH may account for the platelet dysfunction induced by these compounds.