Effect of glutathione depletion on glutathione system in the heart

Purpose

Glutathione (GSH) plays a central role in coordinating the body’s antioxidant defense processes. The present study examined the relative role of endogenous GSH in the circumvention of exercise - induced oxidative stress by using GSH- deficient [L -buthionine - (S, R) -sufloximine (BSO) - treated] rats, and mRNA abundance of GPX were studied in myocardial muscle of rat.

Method

BSO (6mmol/kg body wt/dose) in a 0.9% saline solution twice a day for 8 consecutive days, injection was carried out at 8:30 AM and at 5:30 PM. At the end of the 8 day BSO treatment, GSH - A and GSH - D rat were further divided onto two groups, rested control(R) and exhausted exercise (E). GSH and GSSG concentrations in the heart were analyzed using a fluorometry according to Shel huilin et al. Activities of GPX, was determined at 37o C according to Flohe and gunzle, GR activity was measured at 30oC according to Carlberg and Mannervik, GST activity was measured at 25oC according to Habig et al, GGT activity was measured spectrophotometrically at 37oC according to Meister et al to study GPX expression was used semi-quantitative RT-PCR.

Results

The effect of chronic glutathione (GSX) depletion in vivo by injection L -buthionine - (S, R) -sufloximine (BSO) on intracellular and interorgan GSX regulation was investigated in rat both ta rest and after an acute bout of exhaustive swim exercise. 8-days BSO treatment decreased concentrations of GSX in the heart 6% of the normal levels respectively. This decrease was paralleled with a concomitant decrease of glutathione disulfide (GSSG), thus the GSH/GSSG ratio was maintained. GSH depletion was caused adaptive changes in several enzymes involved in GSH regulation: glutathione peroxides in heart decreased, heart -glutamyltranspeptidase increased (P<0.001 = and glutathione sulfer - transferase in DVL incresed. The GPX mRNA level was increased. It is concluded that the endogenous GSX pool of heart is critically important in the circumvention of exercise - induced oxidative stress and maintenance of physical performance.