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COOH

CYCLO-OXYGÉNASE. CYTOCHROME P-450. 12-LIPOXYGÉNASE. 15-LIPOXYGÉNASE. 5-LIPOXYGÉNASE. La cascade de l’acide arachidonique. ACIDES EPOXY-EICOSATRIÈNOÏQUES, ETC. PROSTAGLANDINES. THROMBOXANE. COOH. ACIDE ARACHIDONIQUE (C20:4). 12-HETE. 15-HETE. HEPOXILINES. LEUCOTRIÈNES.

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COOH

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  1. CYCLO-OXYGÉNASE CYTOCHROME P-450 12-LIPOXYGÉNASE 15-LIPOXYGÉNASE 5-LIPOXYGÉNASE La cascade de l’acide arachidonique ACIDES EPOXY-EICOSATRIÈNOÏQUES, ETC PROSTAGLANDINES THROMBOXANE COOH ACIDE ARACHIDONIQUE (C20:4) 12-HETE 15-HETE HEPOXILINES LEUCOTRIÈNES

  2. La voie de la 5-Lipoxygenase COOH ACIDE ARACHIDONIQUE (C20:4) OOH COOH 5-LIPOXYGÉNASE 5-HpETE COOH O GLUTATHION-S- TRANSFERASE LTA4 OH COOH LTC4 S CH LTA4 HYDROLASE 2 C H (H20) 5 11 CHCONHCH COOH 2 NHCOCH CH CHCOOH 2 2 LTB4 NH HO 2 OH COOH

  3. Activités biologiques des leucotriènes OH COOH S CH2 HO OH C5H11 CHCONHCH2 COOH COOH NHCOCH2 CH2 CHCOOH NH2 LEUCOTRIÈNE B4 (LTB4) LEUCOTRIÈNE C4 (LTC4) -Constriction des muscles lisses du tract respiratoire • Activation & Chimiotaxisme • des phagocytes - Augmente la permeabilité vasculaire

  4. (AA LTA4 LTB4/LTC4) Types de cellules impliquées dans la synthèse de leucotriènes A: exprimant la 5-lipoxygenase Neutrophiles LTB4 Eosinophiles LTC4 Basophiles LTC4 Monocytes LTB4 + LTC4 Macrophages alvéolaires LTB4 Macrophages péritonéaux LTB4 + LTC4 Mastocytes LTB4 + LTC4

  5. (LTA4 LTB4/LTC4) Types de cellules impliquées dans la synthèse de leucotriènes B: exprimant la LTA4 hydrolase ou la GSH-transferase Erythrocytes Lymphocytes Cellules endothéliales Plaquettes

  6. Voie de la Cyclooxygénase COOH O •Vasodilatation COOH •Inhibition des fonctions plaquettaires OH OH AA PGI2 Prostacyclin Cyclooxygénase Synthase O O O COOH COOH PGE2 COOH Synthase OH O •Vasodilatation OH OH OH PGE2 •Douleur O O •Cartilage PGG2 PGH2 Thromboxane COOH O Synthase O OH •Vasoconstriction TXA2 •Aggrégation plaquettaire

  7. O COOH O COOH O OH O Métabolisme des acides gras n-3/n-6 COOH (C20:4 n-6) LTA4 PGG2 AA (PGE2, PGI2, TXA2…) (LTB4, LTC4,…) (Aggrégation) 5-Lipoxygénase Cyclooxygénase (Chimiotaxisme) EPA (C20:5 n-3) O COOH COOH COOH O O OH O LTA5 PGG3 (LTB5, LTC5,…) (PGE3, PGI3, TXA3…) (Moins actif) (Pas d’aggrégation)

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