Clotting of whole human blood induces cysteinyl-leukotriene formation.
Using radioimmunoassay techniques we studied the formation of the 5-lipoxygenase-derived cysteinyl-leukotrienes (LT) in comparison to the cyclooxygenase product thromboxane (TX) B2 in whole human blood allowed to clot at 37 degrees C in vitro. Spontaneous clotting resulted in a time-dependent release of smaller amounts of cysteinyl-LT as well as release of large amounts of TXB2 into the serum. Cysteinyl-LT were characterized by their immunoreactive behaviour and their biological activity in the guinea pig ileum bioassay, an effect which could be antagonized by the SRS-A antagonist FPL 55712 (0.38 microM). By reversed phase HPLC cysteinyl-LT in the serum were identified as a mixture of LTC4, LTD4 and LTE4. At 90 and 120 min part of the immunoreactive material consisted of the omega-oxidized metabolite 20-OH-LTE4. Almost complete inhibition of cyclooxygenase activity by indomethacin (2.8 microM) did not affect cysteinyl-LT formation by clotting whole human blood in vitro nor did activation of platelets by compounds such as the TX mimetic U 46619 (10 microM), platelet-activating factor (PAF, 1 microM) or thrombin (3 IU/ml). In contrast, the lipoxygenase inhibitor nordihydroguaiaretic acid (NDGA, 10 microM), the Ca2+-chelating anticoagulants trisodium citrate (10 microM) and edetate disodium (EDTA, 5.4 mM) as well as the functionally unrelated heparin (20 IU/ml) significantly inhibited the formation of cysteinyl-LT as well as of TXB2. Thus, an event related to the process of clotting of whole human blood appears to be able to induce cysteinyl-LT formation in amounts which might be functionally relevant during thromboembolic events.
Simmet
T
T
Ruhr-University, Department of Pharmacology, Bochum, F.R.G.
Luck
W
W
D000328:Adult; D000818:Animals; D001681:Biological Assay; D001777:Blood Coagulation; D002851:Chromatography, High Pressure Liquid; D002867:Chromones / Q000494:pharmacology; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D004492:Edetic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D007700:Kinetics; D017999:Leukotriene E4; D008297:Male; D009637:Masoprocol / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D013189:SRS-A / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000097:blood* / Q000494:pharmacology; D013929:Thromboxane B2 / Q000097:blood
D002867:Chromones; D002951:Citrates; D013189:SRS-A; D019343:Citric Acid; D013929:Thromboxane B2; D017999:Leukotriene E4; D009637:Masoprocol; C006312:FPL 55712; D006493:Heparin; D004492:Edetic Acid