Effects on interstitial glutathione, cysteine and 5-S-cysteinyldopa of buthionine sulphoximine in human melanoma transplants

Using microdialysis of human melanoma transplants in athymic mice we have shown that interstitial glutathione levels decreased during treatment with buthionine sulphoximine (BSO) and recovered after cessation of treatment. The cysteine concentrations also decreased, while 5-S-cysteinyldopa tended to increase during BSO treatment. Restoration of the glutathione levels was not seen after either N-acetylcysteine (NAC) or L-2-oxothiazolidine-4-carboxylate (OTC) injections, given on the third day of BSO treatment. These results were to be expected since NAC and OTC were given during the BSO treatment, and BSO is a specific and potent inhibitor of glutathione synthesis. Cysteine levels, however, increased after the NAC injection but remained unaltered after the OTC injection, while 5-S-cysteinyldopa remained unaltered after both the NAC and the OTC injections.