title: Monochloramine potently inhibits arachidonic acid metabolism in rat platelets.
abstract: In the present study, the effects of hypochlorous acid (HOCl), monochloramine (NH(2)Cl), glutamine-chloramine (Glu-Cl) and taurine-chloramine (Tau-Cl) on the formation of 12-lipoxygenase (LOX) metabolite, 12-HETE, and cyclooxygenase (COX) metabolites, TXB(2), and 12-HHT, from exogenous arachidonic acid (AA) in rat platelets were examined. Rat platelets (4x10(8)/ml) were preincubated with drugs for 5min at 37 degrees C prior to the incubation with AA (40microM) for 2min at 37 degrees C. HOCl (50-250microM) showed an inhibition on the formation of LOX metabolite (12-HETE, 5-67% inhibition) and COX metabolites (TXB(2), 33-73% inhibition; 12-HHT, 27-74% inhibition). Although Tau-Cl and Glu-Cl up to 100microM were without effect on the formation of 12-HETE, TXB(2) and 12-HTT, NH(2)Cl showed a strong inhibition on the formation of all three metabolites (10-100microM NH(2)Cl, 12-HETE, 21-92% inhibition; TXB(2), 58-94% inhibition; 12-HHT, 36-92% inhibition). Methionine reversed a reduction of formation of LOX and COX metabolites induced by NH(2)Cl, and taurine restoring that induced by both NH(2)Cl and HOCl. These results suggest that NH(2)Cl is a more potent inhibitor of COX and LOX pathways in platelets than HOCl, and taurine and methionine can be modulators of NH(2)Cl-induced alterations in the COX and LOX pathways in vivo.
authors.affiliation: Laboratory of Physiological Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. fujimoto@gly.oups.ac.jp
authors.forename: Yohko
authors.initials: Y
authors.lastname: Fujimoto
authors.forename: Mai
authors.initials: M
authors.lastname: Ikeda
authors.forename: Satoru
authors.initials: S
authors.lastname: Sakuma
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001792:Blood Platelets / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D002700:Chloramines / Q000737:chemistry / Q000494:pharmacology*; D016861:Cyclooxygenase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005973:Glutamine / Q000031:analogs & derivatives / Q000494:pharmacology; D006997:Hypochlorous Acid / Q000494:pharmacology; D016859:Lipoxygenase Inhibitors; D011451:Prostaglandin-Endoperoxide Synthases / Q000187:drug effects*; D051381:Rats; D013654:Taurine / Q000031:analogs & derivatives / Q000494:pharmacology; D013929:Thromboxane B2 / Q000378:metabolism
chemical_list: D002700:Chloramines; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005231:Fatty Acids, Unsaturated; D016859:Lipoxygenase Inhibitors; C511178:glutamine chloramine; D005973:Glutamine; D013654:Taurine; D016718:Arachidonic Acid; C008033:12-hydroxy-5,8,10-heptadecatrienoic acid; C043410:N-chlorotaurine; D013929:Thromboxane B2; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D006997:Hypochlorous Acid; D011451:Prostaglandin-Endoperoxide Synthases; C030816:chloramine