Inhibition of erythrocyte glutathione-peroxidase by bromsulphalein.

42 different samples of human erythrocytes were tested for glutathione-peroxidase activity ) in an attempt to study the inhibitory effect of Bromsulphalein (BSP). The mean activity of the enzyme was 11.90 +/- 3.61 U/g Hb, with no significant difference between males and females. BSP was used at different concentrations from 1 to 45 mM and inhibited GSH-Px activity; the inhibition curve showed a sinusoidal pattern. The major effect was obtained at 30 mM BSP when almost 65% of the initial activity was inhibited. The inhibition of GSH-Px by BSP has also been confirmed using partially purified GSH-Px obtained from human erythrocytes, as well as purified bovine GSH-Px. Some difference was noted between males and females: females may be divided into two subgroups, one with a lower and a second with a higher level of GSH-Px. 1 mM BSP increased the activity in the first group, whereas it reduced the activity in the second group. The inhibition by BSP was positively correlated with the basal value of GSH-Px and this effect was particularly evident in females (r = 0.865; p less than 0.001). The possibility that GSH-Px may be inhibited by BSP would be of some importance considering the strategic role of GSH-Px in protecting the cell from oxidative attack.