Nitric oxide donors inhibit 5-hydroxytryptamine (5-HT) uptake by the human 5-HT transporter (SERT).
1. The aim was to test the hypothesis that nitric oxide (NO) donor drugs can inhibit the 5-hydroxytryptamine (5-HT) transporter, SERT. 2. The NO donors, MAHMA/NO (a NONOate; (Z)-1-[N-methyl-N-[6-(N-methylammoniohexyl)-amino]]diazen-1-ium-1,2-diolate), SIN-1 (a sydnonimine; 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride), FK409 (an oxime; (+/-)-(4-ethyl-2E-(hydroxyimino)-5-nitro-3E-hexenamide)) and peroxynitrite, but not Angeli's salt (source of nitroxyl anion) or sodium nitrite, caused concentration-dependent inhibition of the specific uptake of [3H]-5-HT in COS-7 cells expressing human SERT. 3. Superoxide dismutase (150 U ml(-1)) plus catalase (1200 U ml(-1)), used to remove superoxide and hence prevent peroxynitrite formation, prevented the inhibitory effect of SIN-1 (which generates superoxide) but not of MAHMA/NO or FK409. 4 The inhibitory effects of the NO donors were not affected by the free radical scavenger, hydroxocobalamin (1 mM) or the guanylate cyclase inhibitor, ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 3 microM). 5. L-Cysteine (1 mM; source of excess thiol residues) abolished or markedly reduced the inhibitory effects of MAHMA/NO, SIN-1, FK409 and peroxynitrite. 6. It is concluded that inhibition of SERT by the NO donors cannot be attributed exclusively to NO free radical nor to nitroxyl anion. It does not involve guanosine-3',5'-cyclic monophosphate, but may involve nitrosation of cysteine residues on the SERT protein. Peroxynitrite mediates the effect of SIN-1, but not the other drugs. 7. Data in mice with hypoxic pulmonary hypertension suggest that SERT inhibitors may attenuate pulmonary vascular remodelling. Thus, NO donors may be useful in pulmonary hypertension, not only as vasodilators, but also because they inhibit SERT, provided they display this effect in vivo at appropriate doses.
Department of Physiology & Pharmacology, School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
Lesley J
LJ
Bryan-Lluka
Marisa H
MH
Papacostas
Filip A
FA
Paczkowski
Janet C
JC
Wanstall
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D019556:COS Cells; D002374:Catalase / Q000494:pharmacology; D002522:Chlorocebus aethiops; D003470:Culture Media; D003545:Cysteine / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D006801:Humans; D006879:Hydroxocobalamin / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D009574:Nitro Compounds / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology; D030421:Peroxynitrous Acid / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D012701:Serotonin / Q000378:metabolism*; D050486:Serotonin Plasma Membrane Transport Proteins; D013482:Superoxide Dismutase / Q000494:pharmacology; D014162:Transfection
C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D003470:Culture Media; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D008562:Membrane Glycoproteins; D049990:Membrane Transport Modulators; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D020030:Nitric Oxide Donors; D009574:Nitro Compounds; D010069:Oxadiazoles; D010879:Piperazines; D011810:Quinoxalines; C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins; D030421:Peroxynitrous Acid; D012701:Serotonin; C043425:vanoxerine; C061872:FK 409; D002374:Catalase; D013482:Superoxide Dismutase; D006162:Guanylate Cyclase; D003545:Cysteine; D006879:Hydroxocobalamin