Greenberg S, Xie J, Wang Y, Cai B, Kolls J, Nelson S, Hyman A, Summer W R, Lippton H
Department of Medicine, Louisiana State University Medical Center, New Orleans 70112.
J Appl Physiol (1985). 1993 May;74(5):2394-403. doi: 10.1152/jappl.1993.74.5.2394.
Tumor necrosis factor-alpha (TNF-alpha) stimulates nitric oxide (NO) in vascular endothelium by induction of the enzyme NO synthase II (NOS II). We examined the effects of TNF-alpha on 1) endothelium-dependent (EDR) and endothelium-independent (EIR) relaxation and 2) contraction of bovine intralobar pulmonary arteries (BPA) and veins (BPV) in vitro. Acetylcholine (ACh), bradykinin (BK), histamine, and A23187 produced EDR of BPA contracted with a 50% effective concentration of U-46619 (15 nM), because relaxation was abolished by endothelium-rubbing and attenuated by L-NG-mono-methylarginine (L-NMMA; 300 microM). TNF-alpha (0.00417, 0.0417, 0.417, and 1.25 micrograms/ml) incubated with BPA for 60 min inhibited EDR of the BPA to ACh, BK, and histamine. The effects of TNF required 30 min for onset. Recovery of EDR occurred 3-4 h after washout of TNF-alpha. Pentoxifylline (1 microM) did not affect ACh-induced EDR but selectively reversed TNF-alpha-mediated inhibition of ACh-induced EDR. TNF-alpha-mediated inhibition of EDR was not reversible by L-NMMA, an inhibitor of NOS I and NOS II, the cyclooxygenase inhibitor ibuprofen, or CV-3908 (1 microM), a platelet-activating factor antagonist. The inhibitory effect of TNF-alpha on EDR was not mediated by nonspecific sensitization of the endothelium to human protein because recombinant human granulocyte colony-stimulating factor (10, 50, and 500 x 10(3) U/ml) did not affect EDR of BPA. The effect of TNF-alpha was specific for release of NO from the endothelium of BPA because TNF-alpha did not affect 1) EDR of BPV to ACh, BK, or ATP; 2) EIR of BPA or BPV to nitroprusside; and 3) contraction of either BPA or BPV to KCl, U-46619, histamine, norepinephrine, or serotonin. Thus TNF-alpha appears to selectively inhibit receptor-mediated EDR and NO release in BPA. TNF-alpha-mediated inhibition of EDR differs from that of L-arginine-based inhibitors and may represent an endogenous physiological mechanism of regulation of NO in the endothelium.
肿瘤坏死因子-α（TNF-α）通过诱导一氧化氮合酶II（NOS II）来刺激血管内皮细胞产生一氧化氮（NO）。我们在体外研究了TNF-α对1）内皮依赖性舒张反应（EDR）和非内皮依赖性舒张反应（EIR）以及2）牛肺叶内肺动脉（BPA）和静脉（BPV）收缩的影响。乙酰胆碱（ACh）、缓激肽（BK）、组胺和A23187可使预先用50%有效浓度的U-46619（15 nM）收缩的BPA产生EDR，因为这种舒张反应可被擦去内皮所消除，并被L-NG-单甲基精氨酸（L-NMMA；300 μM）减弱。将TNF-α（0.00417、0.0417、0.417和1.25 μg/ml）与BPA孵育60分钟可抑制BPA对ACh、BK和组胺的EDR。TNF的作用需要30分钟才开始起效。在洗去TNF-α后3 - 4小时，EDR恢复。己酮可可碱（1 μM）不影响ACh诱导的EDR，但能选择性地逆转TNF-α介导的对ACh诱导的EDR的抑制作用。TNF-α介导的对EDR的抑制作用不能被NOS I和NOS II的抑制剂L-NMMA、环氧化酶抑制剂布洛芬或血小板活化因子拮抗剂CV-3908（1 μM）逆转。TNF-α对EDR的抑制作用不是由内皮对人蛋白的非特异性致敏介导的，因为重组人粒细胞集落刺激因子（10、50和500×10³ U/ml）不影响BPA的EDR。TNF-α的作用对BPA内皮释放NO具有特异性，因为TNF-α不影响1）BPV对ACh、BK或ATP的EDR；2）BPA或BPV对硝普钠的EIR；3）BPA或BPV对氯化钾、U-46619、组胺、去甲肾上腺素或5-羟色胺的收缩反应。因此，TNF-α似乎选择性地抑制BPA中受体介导的EDR和NO释放。TNF-α介导的对EDR的抑制作用不同于基于L-精氨酸的抑制剂，可能代表了内皮中NO调节的一种内源性生理机制。
