Leukotriene C promotes prostacyclin synthesis by human endothelial cells.

Abstract

Cultured endothelial cells from human umbilical vein were labeled with [3H]arachidonic acid for 16 hr. The radiolabel was localized primarily in phospholipids (93%) and 73% was distributed equally between phosphatidylcholine and phosphatidylethanolamine. Leukotriene C (10-1,000 nM) promoted a dose-dependent release of radiolabel into the culture medium. This response was 3.3 times control values at 100 nM. The major arachidonic acid metabolite synthesized was prostacyclin, which was 33% of the total released radiolabel. Endothelial cells also released small amounts of prostaglandin F2a (6.1%), unidentified lipoxygenase products (14.8%), and unreacted arachidonic acid (33%). The 30-min time course of release was independent of the leukotriene C concentration used. Leukotriene D at similar concentrations also promoted endothelial cells to release primarily prostacyclin and unreacted arachidonic acid. The release of prostacyclin, a potent vasodilatory agent, may be an important mediator in slow reacting substance effects on the vasculature.Slow reacting substances (SRS) consist of the cysteine-containing leukotrienes (LT) C, D, and E and are derived from the lipoxygenase pathway of arachidonic acid (20:4) metabolism (1). Although the effects of LTC, LTD, and LTE show both quantitative and species differences (2, 3), they are strong smooth muscle stimulants causing bronchial (4), ileal, and uterine (5) contraction. In addition, LTC and LTD are vasoactive. Both compounds produced a transient constriction of arterioles that was followed by exudation from postcapillary venules in the hamster cheek pouch (6). Likewise in monkeys, LTC promoted a rapid, transient pulmonary and systemic hypertension followed by a more prolonged fall in blood pressure with decreased cardiac output (7). This may be due to vasodilation and increased vascular permeability (6, 8), a direct or secondary effect of SRS.To explore possible mechanisms for the vasoactive effect of SRS, human endothelial cells prelabeled with [3H]20:4 were exposed to LTC. The results of this study demonstrate that 10-8 to 10-6 M LTC promotes the release of prostacyclin, a potent vasodilatory agent. MATERIALS AND METHODSMaterials. Radiolabeled prostaglandins (PG) were purchased from New England Nuclear and included 6-keto- [5,8,9,11,12,14,15-3H(N)]PGF1,, (120-180 Ci/mmol; 1 Ci = 3.7 X 10'°Bq), [5,6,8,9,11,12,14,15-3H(N)]thromboxane B2 (100-150 Ci/mnmol), [5,6,8,11,12,14,15_3 H(N)]PGF2,,, and [5,6,8,11,12,14,]PGE2 (100-200 Ci/mmol). Radiolabeled lipoxygenase products were prepared in this laboratory from various sources as described (9,10 [5,6,8,9, 11,12,14,15-3H]20:4 ([3H]20:4) (91.2 Ci/mmol; New England Nuclear). At the end of the labeling period (16 hr), the cells were washed three times with phosphate-buffered saline, placed in medium 199 without serum, and incubated at 370C. Duplicate 50-1l aliquots of medium were removed at the indicated times for radioactivity measurements. At the end of the experiment, the medium was removed, and after washing with ...

Cultured endothelial cells synthesize both platelet-activating factor and prostacyclin in response to histamine, bradykinin, and adenosine triphosphate.

“…This property is not shared by either the substratum or the smooth muscle cells and fibroblasts that underlie the endothelium. The difference in the endothelial cell surface that results in thromboresistance is not defined, but it is known that endothelium (1) and cultured endothelial cells (2) synthesize prostacyclin (PGO2)' in response to a number of physiologic stimuli (3)(4)(5)(6)(7). Initially, the synthesis of this potent inhibitor of platelet aggregation and activation was postulated to participate in the maintenance of a nonthrombogenic surface (1).…”

Leukotriene C4 binds to human glomerular epithelial cells and promotes their proliferation in vitro.

“…The stimulation of mesangial cell proliferation has been attributed to macrophage interleukin-I (12), but the identity of the macrophage-derived factor(s) that increase the growth of epithelial cells is still unknown (11). The purpose of the present study was to determine whether leukotrienes (LTs),' a class of compounds released characteristically by human mononuclear leukocytes (13) (20), and increased vascular permeability in vivo (21).…”

Regional variability of prostacyclin biosynthesis.

“…Pharmacologic and chemical agents that stimulate its production include arachidonate, thrombin, calcium ionophore A23187, trypsin, dipyridamole, histamine, bradykinin, nitroglycerin, angiotensin II, high density lipoprotein, leukotriene C, interieukin-l, and interieukin-ll. 9 - 23 Conversely, PGI 2 formation can be suppressed or abolished by indomethacin, aspirin, tranylcypromine, 15-hydroperoxyarachidonic acid, linoleic acid, low density lipoprotein, glucocorticoids, calcium channel blockers, and cigarette smoke condensate. 59 - 24 - 31 Physiologic alterations, such as disordered blood flow, mechanical stress, high blood pressure, stasis, and low oxygen tension, or morphologic changes can result in enhanced vascular PGI 2 production.…”