Glutathione peroxidase, selenium, and prostaglandin synthesis in platelets

Abstract

Glutathione peroxidase (GSH-Px) contains 4 Se atoms/molecule; its activity is increased by Se dietary intake. The enzyme destroys H2O2 and organic hydroperoxides, contributing to the integrity of biological membranes. GSH-Px activity increased (+ 100%) in washed platelets of rats administered Se (0.3 ppm given as sodium selenite) for 60 days from 10.44 .+-. 1.10 U/g protein (control rats fed a standard diet) to 20.50 .+-. 1.21 U/g protein (mean .+-. SE; P < 0.001). GSH-Px in washed erythrocytes was also stimulated (+ 70%) after 80 days of Se dietary intake from 11.60 .+-. 0.82 U/g Hb to 19.74 .+-. 0.94 U/g Hb (P < 0.001). Malondialdehyde (MDA), the typical breakdown product of peroxidized lipids and a suitable indicator of platelet prostaglandin production, increased from 0.343 .+-. 0.035 nM/3 .times. 108 platelets (control) to 0.478 .+-. 0.052 nM/3 .times. 108 platelets after 30 days of Se treatment (P < 0.05) and to 0.527 .+-. 0.051 nM/3 .times. 108 platelets after 80 days (P < 0.01). MDA was measured by the thiobarbituric acid method after stimulation with 25 .times. 10-4 M arachidonic acid. Platelets apparently are very rich in GSH-Px, i.e., activity is greatly increased by oral administration of Se and the synthesis of prostaglandins is also stimulated.