[Ixeris sonchifolia induced vasoconstriction effect and its mechanism in rat thoracic aorta].
OBJECTIVE
To investigate the vasoconstriction effect of Ixeris sonchifolia in rat thoracic aortic rings and the underlying mechanisms.


METHODS
I. sonchifolia 10-160 g x L(-1) was cumulatively added into organ bath to observe the isometric tension of thoracic aortic rings with intact endothelium or denuded endothelium in basal tension, preconstricted by phenylephrine (PE) or potassium chloride (KCl), and thoracic aortic rings with intact endothelium preincubated frist with captopril, phosphoramidon and indomethacin, respectively, then preconstricted by PE and KCl. The response was recorded and expressed by "relative contraction".


RESULTS
Cumulative administration of I. sonchifolia 10-160 g x L(-1) did not affect the vasomotion of aortic rings with endothelium or without endothelium in basal tension. Exposure of intact endothelium rings preconstricted by PE or KCl to I. sonchifolia at concentration (20-160 g x L(-1) induced a significant constriction, which was inhibited by preincubation with captopril, but was not inhibited by preincubation with phosphoramidon or indomethacin. Exposure of endothelium-denuded rings preconstricted by PE or KCl to I. sonchifolia at concentration (10 to approximately 160 g x L(-1) did not effect the vasoconstriction.


CONCLUSIONS
The results indicate that I. sonchifolia (20 to approximately 160 g x L(-1) can contract the rat thoracic aortic rings with endothelium. The effect of contraction may enhance angiotensin converting enzyme activity and promote endothelium to synthesize angiotensin II. It has no relationship to endothelin or thromboxane A2.
Lin
Yang-Chuang
YC
Department of Cardiology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China.
Hu
Shen-Jiang
SJ
Xu
Dan-Lei
DL
Zheng
Gao-Shu
GS
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000502:physiology; D019659:Asteraceae / Q000737:chemistry*; D002216:Captopril / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D010946:Plants, Medicinal / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D004365:Drugs, Chinese Herbal; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D002216:Captopril