Effects of TNF-alpha on the production of vasoactive substances by cerebral endothelial and smooth muscle cells in culture.
The effects of tumor necrosis factor-alpha (TNF-alpha) on the production of the vasoactive substances nitric oxide (NO) and endothelin-1 (ET-1) were investigated in cerebrovascular cells in culture. Bovine cerebral endothelial cells (BCEC) stained positively for NADPH-diaphorase/NO synthase activity and spontaneously produced nitrite, a stable NO oxidation product, which accumulated in the culture medium in a linear way for 48 h. Low concentrations of TNF-alpha (0.5-2 ng/ml) significantly enhanced nitrite production after a 24-h incubation. Higher concentrations or longer exposure times resulted in a cytotoxic effect that altered cell morphology, released lactate dehydrogenase (LDH) to the culture medium, and reduced the protein content. Dexamethasone, but not the NO synthase inhibitor N-iminoethyl-L-ornithine (L-NIO), prevented the cytotoxic effect of TNF-alpha in BCEC. TNF-alpha also significantly enhanced nitrite production in bovine cerebral smooth muscle cells (BCSMC). The enhancement was detected at all times between 8 and 72 h and at all concentrations tested (2-100 ng/ml). Signs of cytotoxicity were not observed in BCSMC after incubation with TNF-alpha. ET-1 was constitutively secreted by BCEC. The production of ET-1 was stimulated by thrombin. TNF-alpha enhanced the release of ET-1 in BCEC, and this enhancement was not modified by the simultaneous addition of interferon-gamma (IFN-gamma). BCSMC did not produce ET-1, either spontaneously or in the presence of TNF-alpha, IFN-gamma, or of both together.(ABSTRACT TRUNCATED AT 250 WORDS)
Estrada
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Department of Physiology, Faculty of Medicine, Universidad Autónoma de Madrid, Spain.
Gómez
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Martín
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D000818:Animals; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002560:Cerebrovascular Circulation / Q000187:drug effects* / Q000502:physiology*; D016232:Endothelins / Q000096:biosynthesis; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D016232:Endothelins; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide