Polte T, Schröder H
School of Pharmacy, Martin Luther University, Wolfgang-Langenbeck-Strasse 4, Halle (Saale), 06099, Germany.
Biochem Biophys Res Commun. 1998 Oct 20;251(2):460-5. doi: 10.1006/bbrc.1998.9486.
Incubation with TNF-alpha (50 ng/ml) for 72 hours markedly reduced viability of endothelial cells. A 6-hour preincubation with S-nitroso-N-acetyl-D,L-penicillamine (SNAP, 3-100 microM) protected cells in a concentration-dependent manner and decreased TNF-alpha-mediated toxicity by up to 70%. Cytoprotection by SNAP was completely abolished by the adenylyl cyclase inhibitor 2', 5'-dideoxyadenosine and mimicked by 8-bromo cyclic AMP or forskolin. SNAP produced significant increases in cyclic GMP and cyclic AMP, both being abrogated in the presence of the NO scavenger 2-phenyl-4, 4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). Moreover, no endothelial protection by SNAP was detected in the presence of the protein kinase A inhibitor KT5720, whereas the protein kinase G inhibitor KT5823 left cytoprotection virtually unaltered. Our results demonstrate a crucial role for cyclic AMP in mediating NO-induced endothelial protection against TNF-alpha, possibly through cyclic GMP-dependent inhibition of cyclic AMP breakdown. NO-dependent endothelial protection may ultimately result from cyclic AMP-induced up-regulation of antioxidant proteins or down-regulation of cytotoxic processes.
用肿瘤坏死因子-α（TNF-α，50纳克/毫升）孵育72小时可显著降低内皮细胞的活力。用亚硝基硫醇（S-nitroso-N-acetyl-D,L-penicillamine，SNAP，3 - 100微摩尔）预孵育6小时可浓度依赖性地保护细胞，并将TNF-α介导的毒性降低多达70%。腺苷酸环化酶抑制剂2'，5'-二脱氧腺苷可完全消除SNAP的细胞保护作用，而8-溴环磷酸腺苷（8-bromo cyclic AMP）或福斯可林（forskolin）可模拟该作用。SNAP可显著增加环磷酸鸟苷（cyclic GMP）和环磷酸腺苷（cyclic AMP），在一氧化氮清除剂2-苯基-4,4,5,5-四甲基咪唑啉-1-氧基-3-氧化物（PTIO）存在的情况下，二者的增加均被消除。此外，在蛋白激酶A抑制剂KT5720存在的情况下未检测到SNAP对内皮细胞的保护作用，而蛋白激酶G抑制剂KT5823对细胞保护作用几乎没有影响。我们的结果表明，环磷酸腺苷在介导一氧化氮诱导的内皮细胞对TNF-α的保护中起关键作用，可能是通过环磷酸鸟苷依赖性抑制环磷酸腺苷的分解。一氧化氮依赖性内皮细胞保护最终可能源于环磷酸腺苷诱导的抗氧化蛋白上调或细胞毒性过程下调。
