Inhibition of inducible nitric oxide synthase by beta-lapachone in rat alveolar macrophages and aorta.
Beta-lapachone, a plant product, has been shown to be a novel inhibitor of DNA topoisomerase. In this study, we performed experiments to examine the effects of beta-lapachone on lipopolysaccharide (LPS)-induced inducible nitric oxide (NO) synthase (iNOS) in rat alveolar macrophages and aortic rings. In alveolar macrophages, incubation with LPS (10 microg ml(-1)) for various time intervals resulted in a significant increase in nitrite production and iNOS protein synthesis, that was inhibited by coincubation with beta-lapachone (1-4.5 microM) without any cytotoxic effects. However, addition of beta-lapachone after induction of NO synthase by LPS failed to affect the nitrite production. Treatment with LPS (10 microg ml(-1)) for 6 h resulted in significant expression of mRNA for iNOS which was significantly inhibited in the presence of beta-lapachone (3 microM) in alveolar macrophages. In endothelium-intact rings of thoracic aorta, beta-lapachone (1 and 3 microM) markedly inhibited the hypocontractility to phenylephrine in aortic rings treated with LPS (10 microg ml(-1)) for 4 h. When beta-lapachone was added 3 h after LPS into the medium, the contractions evoked by phenylephrine were not significantly different in the presence or absence of beta-lapachone. Treatment with LPS (10 microg ml(-1)) for 4 h resulted in a significant increase in iNOS protein synthesis which was inhibited in the presence of beta-lapachone (3 microM), but did not affect the constitutive (endothelial and neuronal) NOS forms in aortic rings. These results indicate that beta-lapachone is capable of inhibiting expression and function of iNOS in rat alveolar macrophages and aortic rings. It is considered that beta-lapachone can be developed as a potential anti-inflammatory agent in the future.
Liu
S H
SH
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei.
Tzeng
H P
HP
Kuo
M L
ML
Lin-Shiau
S Y
SY
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D008070:Lipopolysaccharides / Q000494:pharmacology; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000201:enzymology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009285:Naphthoquinones / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D009573:Nitrites / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D059004:Topoisomerase I Inhibitors; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009285:Naphthoquinones; D009573:Nitrites; D059004:Topoisomerase I Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; C014638:beta-lapachone; C496320:NOS1 protein, human; C496319:NOS2 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; C496316:Nos3 protein, rat