Antagonism by paraquat of the relaxing effects of acetylcholine and A23187 in rat thoracic aorta

Hsu Kuei-Sen Hsu, Lin-Shiau Shoei-Yn Lin-Shiau

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


Paraquat, a widely used herbicide, has been reported to be capable of producing superoxide. In the present paper, therefore, the possibility of paraquat inhibiting endothelium-dependent relaxation, mediated by the production of nitric oxide, was tested. The relaxing effects of acetylcholine and A23187, but not that of sodium nitroprusside, in the rat thoracic aorta were found to be inhibited by paraquat in a concentration-dependent manner. In contrast, paraquat was totally inactive with regard to the aortic contractions induced by either norepinephrine or prostaglandin F. The inhibitory action of paraquat could be antagonized by superoxide dismutase but not by catalase and indomethacin. All of these findings indicate that superoxide anions produced by paraquat in the endothelium contribute to a decrease in the relaxation response to acetylcholine and A23187 by interfering with endothelium-derived nitric oxide.

Original languageEnglish
Pages (from-to)315-320
Number of pages6
JournalEuropean Journal of Pharmacology: Environmental Toxicology and
Issue number3-4
Publication statusPublished - 1995 Mar 16

All Science Journal Classification (ASJC) codes

  • Toxicology
  • Pharmacology
  • Pollution


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