Fluorescence intensity of 50 μmol/L cis-parinaric acid in a 2 mL suspension of red cells, 10% hematocrit, in PBS with 10 mmol/L glucose and 50 μg/mL gentamycin.

Readings were taken every 15 seconds. After 150 seconds of equilibration, either 50 μL cumene hydroperoxide in ethanol was added (100 μmol/L final concentration) (filled symbols), or 50 μL ethanol (open symbols) was added to controls. There was no difference between the rate of fluorescence loss in wild-type red cells (circles) and GSHPx-1–deficient red cells (squares).Two runs are shown.