[Effect of iron on vasoconstriction in the isolated rat aorta].
The present study 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 (FAC) (100 micromol/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+/-2.37% of the maximal contraction induced by KCl, 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 by 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 PDBu. (4) Pretreatment of FAC for 30 min decreased the KCl-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 KCl- or PE-induced contractions in isolated thoracic arteries. Reactive oxygen species and glutathione may be involved in iron-induced contraction dysfunction.
Kuang
Wei
W
Department of Physiology, Zhejiang University School of Medicine, Hangzhou 310031.
Chen
Ying-Ying
YY
Shen
Yue-Liang
YL
Xia
Qiang
Q
D000818:Animals; D001013:Aorta, Thoracic / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D005290:Ferric Compounds / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D066298:In Vitro Techniques; D007501:Iron / Q000494:pharmacology*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects* / Q000502:physiology
D020746:Calcium Channels, L-Type; D005290:Ferric Compounds; D000644:Quaternary Ammonium Compounds; D017382:Reactive Oxygen Species; D007501:Iron; D005978:Glutathione; D002118:Calcium; C013531:ferric ammonium citrate