Stimulation of 12-HETE production in human platelets by an immunomodulator, LF 1695. Evidence for activation of arachidonate liberation coupled to cyclo-oxygenase inhibition.
Upon incubation with human platelets previously labelled with [14C]arachidonic acid, a new immunomodulator, LF 1695, induced the accumulation of [14C]-12-(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). Although the time course of [14C]HETE accumulation was identical with 60 microM LF 1695 and calcium ionophore A23187, the latter compound also promoted the formation of 14C-labelled thromboxane B2 and 12-(S)-hydroxy-5,8,10-heptadecatrienoic acid (HHT), whereas 12-HETE was the only arachidonic acid metabolite generated under the action of LF 1695, suggesting that the drug inhibited cyclo-oxygenase. This was further confirmed by the fact that LF 1695 inhibited the second wave of platelet aggregation induced by ADP as well as arachidonic acid effects. Cell lipid analysis revealed that arachidonic acid was liberated from both triacylglycerol and phosphatidylcholine. The effect was observed in the concentration range 15-90 microM, with a half-maximal effect at 30 microM for HETE production, 15 microM for triacylglycerol hydrolysis and 45 microM for phosphatidylcholine deacylation. Incubation of platelets with [14C]arachidonic acid in the presence of 60 microM LF 1695 resulted in a strong inhibition of arachidonic acid incorporation into the various cell lipids, indicating that arachidonic acid mobilization might be due to inhibition of reacylation processes. It is concluded that LF 1695 displays an original and complex effect on platelet lipid metabolism, resulting in the specific generation of lipoxygenase metabolites.
Hullin
F
F
INSERM Unité 101, Biochimie des Lipides, Hôpital Purpan, Toulouse, France.
Ragab-Thomas
J M
JM
Sepulchre
C
C
Pascal
M
M
Chap
H
H
Douste-Blazy
L
L
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood*; D001241:Aspirin / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D000001:Calcimycin / Q000502:physiology; D016861:Cyclooxygenase Inhibitors; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis*; D066298:In Vitro Techniques; D010880:Piperidines / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects; D010975:Platelet Aggregation Inhibitors; D013917:Thrombin / Q000502:physiology
D000276:Adjuvants, Immunologic; D001095:Arachidonic Acids; D016861:Cyclooxygenase Inhibitors; D006893:Hydroxyeicosatetraenoic Acids; D010880:Piperidines; D010975:Platelet Aggregation Inhibitors; D015117:5,8,11,14-Eicosatetraynoic Acid; D016718:Arachidonic Acid; D000001:Calcimycin; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C046743:LF 1695; D013917:Thrombin; D001241:Aspirin