L-buthionine sulfoximine-induced loss of glutathione does not elicit PGH synthase inactivation in cultured bovine lens epithelial cells.
Previous studies from this laboratory have indicated that exposure of cultured bovine lens epithelial cells (BLECs) to minimal essential medium (MEM) containing 40 mM galactose (Gal) for as short a duration as 20 h results in a reduction of microsomal prostaglandin biosynthesis as demonstrated by a decrease in PGH synthase activity (Invest. Ophthalmol. Vis. Sci. 29:1452-1460, 1988). The present study shows that upon brief exposure of BLECs to Gal, the cellular content of glutathione (GSH) decreases as galactitol increases. Studies were therefore undertaken to establish whether a positive correlation existed between polyol accumulation, GSH content and the activity of PGH synthase (an enzyme known to auto-oxidize) utilizing BLECs exposed to hypergalactosemic conditions. The inhibitor of glutathione biosynthesis, L-buthionine sulfoximine (L-BSO) was used in order to lower the intracellular pool of GSH in MEM-incubated cells to a level below that routinely observed in Gal-incubated cells, under conditions whereby no galactitol accumulation had occurred. The galactitol content was 92 nmol/micrograms PO4 in Gal-incubated cells after a 20 h exposure period; no detectable level of galactitol was observed in BLECs maintained in galactose-free MEM. L-(BSO) (1 mM) was co-administered to BLECs maintained in either MEM or Gal for 20 h. The cellular content of GSH was 1.70 +/- .02 micrograms GSH/micrograms PO4 in MEM alone and 0.540 +/- .02 micrograms GSH/micrograms PO4 in MEM + BSO. Furthermore, the GSH content in BLECs after 20 h of exposure to Gal was 0.960 +/- .01 microgram GSH/microgram PO4 but decreased to 0.110 +/- .01 microgram GSH/microgram PO4 in Gal + BSO.(ABSTRACT TRUNCATED AT 250 WORDS)
Cammarata
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PR
Department of Anatomy, Texas College of Osteopathic Medicine, Fort Worth.
Yorio
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D000449:Aldehyde Reductase / Q000378:metabolism; D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology*; D019328:Buthionine Sulfoximine; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D004789:Enzyme Activation; D004847:Epithelial Cells; D005690:Galactose / Q000494:pharmacology; D005978:Glutathione / Q000096:biosynthesis*; D007424:Intracellular Fluid / Q000378:metabolism; D007903:Lens Capsule, Crystalline / Q000201:enzymology* / Q000378:metabolism; D007908:Lens, Crystalline / Q000201:enzymology*; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011108:Polymers / Q000378:metabolism; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*
D000963:Antimetabolites; D003470:Culture Media; D011108:Polymers; C024617:polyol; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D000449:Aldehyde Reductase; D011451:Prostaglandin-Endoperoxide Synthases; D005978:Glutathione; D005690:Galactose