Modulation of alveolar macrophage lipoxygenase metabolism by the sulfhydryl-reactive compound
N-ethylmaleimide (NEM), a sulfhydryl(SH)-reactive compound, has been previously shown to trigger arachidonic acid (AA) release and thromboxane (TxB/sub 2/) synthesis in alveolar macrophages (AMs). The present study was undertaken to characterize the effects of this agent on rat AM lipoxygenase metabolism. NEM caused dose-dependent stimulation of TxB/sub 2/ and, to a lesser extent, PGE/sub 2/ synthesis. However, NEM at either 5 or 10 ..mu..M failed to stimulate production of LTB/sub 4/ (control= 31 + 6, 5 ..mu..M = 36 + 8, 10 ..mu..M = 39 +/- 14 pg/ml; mean + SEM, n = 3) or LTC/sub 4/ (control = 109 +/- 29, 5 ..mu..M = 111 + 27, 10 ..mu..M = 113 +/- 40 pg/ml; n = 4). Indomethacin (5 ..mu..M) failed to shunt AA towards LTB/sub 4/ or LTC/sub 4/ synthesis in response to 10 ..mu..M NEM. In addition, /sup 14/C-5-HETE production by /sup 14/C-AA prelabeled AMs was no greater in NEM-treated cultures (308 +/- 96 cpm) than in control cultures (321 +/- 159 cpm/4 x 10/sup 6/ cells). The effect of NEM on zymosan-induced eicosanoid synthesis was examined by incubating AMs with zymosan (100 ..mu..g/ml) for 1 hour + NEM. NEM (10 ..mu..M) inhibited zymosan-induced LTC/sub 4/ synthesis (control = 122 +/- 43, zymosan = 266 +/- 35, zymosan + NEM = 105 +/- 38 pg/ml; n = 3; p = .05) without cytotoxicity, and while yielding additive increments in TxB/sub 2/ and PGE/sub 2/. Since the actions of both 5-lipoxygenase and glutathione transferase represent SH-dependent steps in the synthesis of LTs, it is postulated that the SH reactivity of NEM explains both its inability to stimulate LT synthesis and its ability to inhibit zymosan-induced LTC/sub 4/ synthesis.
- Research Organization:
- Univ. of Michigan, Ann Arbor
- OSTI ID:
- 5388960
- Report Number(s):
- CONF-8604222-; TRN: 86-030453
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
NEM
BIOLOGICAL EFFECTS
OXYGENASES
METABOLISM
ARACHIDONIC ACID
CARBON 14 COMPOUNDS
DOSE-RESPONSE RELATIONSHIPS
MACROPHAGES
RATS
TRACER TECHNIQUES
ZYMOSAN
ANIMAL CELLS
ANIMALS
ANTIMITOTIC DRUGS
CARBOXYLIC ACIDS
CONNECTIVE TISSUE CELLS
DRUGS
ENZYMES
IMIDES
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MAMMALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
PHAGOCYTES
RADIOSENSITIZERS
RODENTS
SOMATIC CELLS
VERTEBRATES
550201* - Biochemistry- Tracer Techniques