Effect of inhibition of 5-lipoxygenase metabolism of arachidonic acid on response to endotoxemia in sheep.
We studied the effects of a 5-lipoxygenase inhibitor, L-651,192, on the pulmonary dysfunction caused by endotoxemia in chronically instrumented unanesthetized sheep. The efficacy and selectivity of L-651,392 were tested by measuring in vivo production of leukotriene B4 (LTB4) and cyclooxygenase products of arachidonic acid after endotoxemia before and after pretreatment with L-651,392 and ex vivo from granulocytes and whole blood stimulated with calcium ionophore from sheep before and 24 h after pretreatment with L-651,392. A novel assay for LTB4 by high-performance liquid chromatography/gas chromatography/mass spectrometry techniques was developed as a measure of 5-lipoxygenase metabolism of arachidonic acid. L-651,392 proved to be an effective in vivo 5-lipoxygenase inhibitor in sheep. L-651,392 blocked the increase in LTB4 observed in lung lymph after endotoxemia in vivo in sheep as well as inhibited by 80% the ex vivo production of LTB4 by granulocytes removed from sheep treated 24 h earlier with L-651,392. Although L-651,392 blocked the increase in cyclooxygenase products of arachidonic acid observed in lung lymph after endotoxemia in vivo in sheep, the drug probably did not function directly as a cyclooxygenase inhibitor. L-651,392 did not attenuate the ex vivo production of thromboxane B2 by whole blood from sheep treated 24 h earlier with the drug. L-651,392 attenuated the alterations in pulmonary hemodynamics, lung mechanics, oxygenation, and lung fluid and solute exchange observed after endotoxemia in sheep. We speculate that 5-lipoxygenase products are a major stimulus for cyclooxygenase metabolism of arachidonic acid after endotoxemia in sheep.
Coggeshall
J W
JW
Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Christman
B W
BW
Lefferts
P L
PL
Serafin
W E
WE
Blair
I A
IA
Butterfield
M J
MJ
Snapper
J R
JR
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001091:Arachidonate Lipoxygenases / Q000037:antagonists & inhibitors*; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism*; D004731:Endotoxins / Q000633:toxicity; D005260:Female; D006098:Granulocytes / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D007975:Leukotriene B4 / Q000096:biosynthesis; D016859:Lipoxygenase Inhibitors; D008168:Lung / Q000187:drug effects / Q000503:physiopathology; D008196:Lymph / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010640:Phenothiazines / Q000494:pharmacology; D011652:Pulmonary Circulation / Q000187:drug effects; D012128:Respiratory Distress Syndrome / Q000209:etiology / Q000503:physiopathology; D012756:Sheep; D014115:Toxemia / Q000139:chemically induced / Q000503:physiopathology*
D001095:Arachidonic Acids; D004731:Endotoxins; D016859:Lipoxygenase Inhibitors; D010640:Phenothiazines; D007975:Leukotriene B4; D016718:Arachidonic Acid; C053726:4-bromo-2,7-dimethoxy-3H-phenothiazin-3-one; D001091:Arachidonate Lipoxygenases; D001094:Arachidonate 5-Lipoxygenase