Transformation of 5-hydroperoxyeicosatetraenoic acid into dihydroxy- and cysteinyl-leukotrienes by rat hepatocytes: effects of glutathione.
In the presence of glutathione (GSH 400 microM), rat hepatocyte homogenates converted 5-hydroperoxyeicosatetraenoic acid (5-HPETE), via the intermediate leukotriene A4, into leukotriene C4 (LTC4) and leukotriene B4 (LTB4); 5-hydroxyeicosatetraenoic acid (5-HETE) was also a prominent product. During a 5-min incubation with 100 microM (13.4 microgram) 5-HPETE, 0.24 ng of LTC4, 15.4 ng of all-trans-LTB4, 4.3 ng of LTB4, and 12.4 micrograms of 5-HETE were formed/mg of protein. In incubations devoid of GSH, 38.6 ng of all-trans-LTB4, 8.8 ng of LTB4, and 2.2 micrograms of 5-HETE were formed/mg of protein, and 3.3 micrograms of intact 5-HPETE could be recovered. The presence of GSH induced a time-dependent rapid depletion of 5-HPETE, paralleled by large increases in the formation of 5-HETE; formation of LTC4 was detected in the presence but not in the absence of GSH. Addition of thiomalic acid (0.1 mM) or penicillamine (0.2 mM), both inhibitors of selenium-dependent GSH peroxidases, increased formation rates of LTC4 by factors of 3 and 2, respectively, whereas the suppressive effects of GSH on the formation of LTB4 were partially reversed. These results suggest that hepatocytes are capable of the simultaneous synthesis of cysteinyl- and dihydroxy-leukotrienes as well as 5-HETE; the availability of the precursor 5-HPETE and the profile of leukotrienes formed are dependent on the GSH concentration and the extent of GSH peroxidase activity.
Huwyler
J
J
Department of Pharmacology, Biocenter of the University, Basel, Switzerland.
Bürgin
M
M
Zeugin
T
T
Gut
J
J
D000818:Animals; D002474:Cell-Free System; D002851:Chromatography, High Pressure Liquid; D005978:Glutathione / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000037:antagonists & inhibitors / Q000378:metabolism; D007728:Kupffer Cells / Q000378:metabolism; D007975:Leukotriene B4 / Q000378:metabolism*; D015289:Leukotrienes / Q000378:metabolism*; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013189:SRS-A / Q000378:metabolism*; D013870:Thiomalates / Q000494:pharmacology; D013997:Time Factors
D015289:Leukotrienes; D013189:SRS-A; D013870:Thiomalates; D007975:Leukotriene B4; C025348:arachidonic acid 5-hydroperoxide; C046062:2-thiomalic acid; D005979:Glutathione Peroxidase; D005978:Glutathione