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Effect of iron on vasoconstriction in the isolated rat aorta

KUANG Wei, Chen Yingying, SHEN Yue-Liag, Xia Qiang

Department of Physiology, Zhejiang University Medicine, Hangzhou 310031；Department of Physiology of Technical College，Ningbo 315000

Abstract

The present stu勿was to examine the effect of iron on isolated rat aortic rings，and to elucidate the underlying mechanism .The thoracic aortic rings without endothelium of male Sprague- Dawley rats were mounted on a bath system .Isometric contractions of aortic rings were measured. The results obtained are as follows.(1)Ferric ammonium citrate(FAQ(100 p mol/ L) caused a phasic response with an initial transient contraction followed by a relaxation in thoracic aortic ring.The maximal contractile amplitude was 24. 02士2.37‘the maximal contraction induced by K the duration of phasic contraction lasted for about 20 min.(2) In high Ca~(2+)Krebs- Henseleit(K H) solution(twice of the normal concentration)，the contractile amplitude induced FAC
was enhanced.After the aortic rings were incubated with nifedipine for 15 min to block the L type Ca~(2+)channel，the iron-induced contraction was attenuated.(3) In Ca~(2+)--free K H solution，addition of FAC caused a strong
and sustained contraction in the presence of PDBi.(4) Pretreatment of FAC for 30 min decreased the KCI-induced contraction and also caused a significant reduction in the contractile response to phenylephrine(PE).Pretreatment of the arteries with DMSO，catalase or glutathione before FAC exposure prevented the decrease in contraction responses to PE(P<0.05).It is therefore concluded that iron causes phasic contraction of vascular smooth muscle，in which both extracellular Ca~(2+)entry through L -type Ca~(2+)channel and increase in Ca~(2+)sensitivity of smooth muscle cells are involved .Exposure to iron causes inhibitory effects on K〔一or PE induced contractions in isolated thoracic arteries.Reactive oxygen species and glutathione may be involved in iron-induced contraction dysfunction.
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Key words: iron;thoracic aorta;vasoconstriction;L type Ca~(2+)channel;reactive oxygen species

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Citing This Article：

KUANG Wei, Chen Yingying, SHEN Yue-Liag, Xia Qiang. Effect of iron on vasoconstriction in the isolated rat aorta. Acta Physiol Sin 2003; 55 (3): (in Chinese with English abstract).