Tumor necrosis factor-alpha inhibits endothelium-dependent relaxation.
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.
Greenberg
S
S
Department of Medicine, Louisiana State University Medical Center, New Orleans 70112.
Xie
J
J
Wang
Y
Y
Cai
B
B
Kolls
J
J
Nelson
S
S
Hyman
A
A
Summer
W R
WR
Lippton
H
H
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002417:Cattle; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology; D007052:Ibuprofen / Q000494:pharmacology; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009126:Muscle Relaxation / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology; D010431:Pentoxifylline / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects; D011667:Pulmonary Veins / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D019323:omega-N-Methylarginine
D011450:Prostaglandin Endoperoxides, Synthetic; D014409:Tumor Necrosis Factor-alpha; D014662:Vasoconstrictor Agents; D019323:omega-N-Methylarginine; D011189:Potassium Chloride; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D006632:Histamine; D001120:Arginine; D000109:Acetylcholine; D010431:Pentoxifylline; D007052:Ibuprofen; D009638:Norepinephrine