TY - JOUR
T1 - Alterations in intracellular thiol homeostasis during the metabolism of menadione by isolated rat hepatocytes
AU - Di Monte, Donato
AU - Ross, David
AU - Bellomo, Giorgio
AU - Eklöw, Lena
AU - Orrenius, Sten
N1 - Funding Information:
This study was supported by grants from the Swedish Medical Research Council, Karolinska In-stitutet, and the Consiglio Nationale delle Ricerche.
PY - 1984/12
Y1 - 1984/12
N2 - The effects of menadione (2-methyl-1,4-naphthoquinone) metabolism on intracellular soluble and protein-bound thiols were investigated in freshly isolated rat hepatocytes. Menadione was found to cause a dose-dependent decrease in intracellular glutathione (GSH) level by three different mechanisms: (a) Oxidation of GSH to glutathione disulfide (GSSG) accounted for 75% of the total GSH loss; (b) About 15% of the cellular GSH reacted directly with menadione to produce a GSH-menadione conjugate which, once formed, was excreted by the cells into the medium; (c) A small amount of GSH (~10%) was recovered by reductive treatment of cell protein with NaBH4, indicating that GSH-protein mixed disulfides were also formed as a result of menadione metabolism. Incubation of hepatocytes with high concentrations of menadione (>200 μm) also induced a marked decrease in protein sulfhydryl groups; this was due to arylation as well as oxidation. Binding of menadione represented, however, a relatively small fraction of the total loss of cellular sulfhydryl groups, since it was possible to recover about 80% of the protein thiols by reductive treatments which did not affect protein binding. This suggests that the loss of protein sulfhydryl groups, like that of GSH, was mainly a result of oxidative processes occurring within the cell during the metabolism of menadione.
AB - The effects of menadione (2-methyl-1,4-naphthoquinone) metabolism on intracellular soluble and protein-bound thiols were investigated in freshly isolated rat hepatocytes. Menadione was found to cause a dose-dependent decrease in intracellular glutathione (GSH) level by three different mechanisms: (a) Oxidation of GSH to glutathione disulfide (GSSG) accounted for 75% of the total GSH loss; (b) About 15% of the cellular GSH reacted directly with menadione to produce a GSH-menadione conjugate which, once formed, was excreted by the cells into the medium; (c) A small amount of GSH (~10%) was recovered by reductive treatment of cell protein with NaBH4, indicating that GSH-protein mixed disulfides were also formed as a result of menadione metabolism. Incubation of hepatocytes with high concentrations of menadione (>200 μm) also induced a marked decrease in protein sulfhydryl groups; this was due to arylation as well as oxidation. Binding of menadione represented, however, a relatively small fraction of the total loss of cellular sulfhydryl groups, since it was possible to recover about 80% of the protein thiols by reductive treatments which did not affect protein binding. This suggests that the loss of protein sulfhydryl groups, like that of GSH, was mainly a result of oxidative processes occurring within the cell during the metabolism of menadione.
UR - http://www.scopus.com/inward/record.url?scp=0021671419&partnerID=8YFLogxK
U2 - 10.1016/0003-9861(84)90206-6
DO - 10.1016/0003-9861(84)90206-6
M3 - Article
SN - 0003-9861
VL - 235
SP - 334
EP - 342
JO - Archives of Biochemistry and Biophysics
JF - Archives of Biochemistry and Biophysics
IS - 2
ER -