Endothelial cells can synthesize leukotriene B4

Abstract

Leukotriene B4 (LTB4) from vascular endothelium may play a key role in the genesis of atherosclerotic lesions. However, the ability of this tissue to synthesize LTB4 is controversial. To resolve this issue arachidonic acid metabolism was characterized in cultures of confluent monolayers of a rabbit aortic endothelial cell line by use of both high-pressure liquid chromatography and radioimmunoassay. Cells were grown to confluence in Dulbecco's modified Eagle's medium/Ham's F12 with 5% fetal bovine serum. Lipoxygenase activity was studied by placing the cells in Hank's balanced salt solution with 2 mumol/L indomethacin. After 30 minutes preincubation with indomethacin cells were exposed to either arachidonic acid (10 mumol/L) or arachidonic acid labeled with radioactive carbon (14C) (1 microCi; SA 58 mCi/mmol) and then stimulated with 9.5 mumol/L calcium ionophore A23187 for 55 minutes. Studies of the cyclooxygenase activity were performed without preincubating with indomethacin. Samples were prepared for high-pressure liquid chromatography by evaporation to dryness under a vacuum and resuspending in 2 ml of 1:1 methanol/water. Tritium-labeled standards were added before loading the 14C-labeled samples on the column. Radiolabeled arachidonic acid metabolites were separated by high-pressure liquid chromatography and detected by means of a dual channel flow-through radiodetector that monitors both 14C and 3H. Based on coelution with authentic standards three lipoxygenase metabolites of arachidonic acid have been identified: LTB4, 12- and 5-hydroxyeicosatetraneoic acid. Leukotriene B4 was further characterized by ultraviolet spectral analysis and inhibition studies with use of nordihydroguaiaretic acid. Quantitation was facilitated by commercially available radioimmunoassay kits. An average of 600 pg LTB4/10(6) cells was measured from separate experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Cysteinyl leukotrienes and leukotriene B4 mediate vasoconstriction to arginine vasopressin in rat basilar artery

“…The present data clearly indicate a connection between AVP‐induced contraction and the 5‐lipoxygenase pathway in the rat basilar artery. The expression of 5‐lipoxygenase and LTA 4 hydrolase (the enzyme involved in LTB 4 synthesis) has been reported in systemic vessels 21,29 and both endothelial and smooth muscle cells are able to produce leukotrienes 10–13 . Furthermore, 5‐lipoxygenase is upregulated in ageing‐associated cerebral disorders, such as atherosclerosis, cerebral ischaemia and vasospasm 21,30,31 …”

“…The expression of 5-lipoxygenase and LTA4 hydrolase (the enzyme involved in LTB4 synthesis) has been reported in systemic vessels 21,29 and both endothelial and smooth muscle cells are able to produce leukotrienes. [10][11][12][13] Furthermore, 5-lipoxygenase is upregulated in ageing-associated cerebral disorders, such as atherosclerosis, cerebral ischaemia and vasospasm. 21,30,31 Cysteinyl leukotrienes activate two types of receptors, CysLT1 and CysLT2 receptors, activation of both of which stimulates intracellular calcium mobilization.…”

“…The inflammatory enzyme 5‐lipoxygenase catalyses the production of cysteinyl leukotrienes (CysLTs; leukotriene (LT) C 4 , LTD 4 and LTE 4 ) and LTB 4 from arachidonic acid. In the arterial wall, leukotrienes are produced by both endothelial and smooth muscle cells 10–13 . Under pathological conditions (e.g.…”

“…In the arterial wall, leukotrienes are produced by both endothelial and smooth muscle cells. [10][11][12][13] Under pathological conditions (e.g. hypertension, atherosclerosis, after SAH), the infiltration of monocyte/macrophages into the vascular wall may contribute to an increase in the production of leukotrienes.…”

Cysteinyl leukotrienes mediate enhanced vasoconstriction to angiotensin II but not endothelin-1 in SHR

“…Moreover, LTD 4 -evoked pressor responses were shown to be higher in SHR (36). Recent studies (9,20,23,24) also demonstrated that leukotrienes are synthesized and generated from vascular endothelial cells and VSM cells. Therefore, the present study was undertaken to assess the role of leukotrienes in ANG II-evoked vasoconstrictor responses ex vivo in the perfused mesenteric vascular bed (MVB) isolated from Wistar-Kyoto (WKY) rats and SHR.…”