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Xue W, Zhang M, Li J, Wu D, Niu L, Liang Y: Effects of taurine on aortic rings isolated from fructose-fed insulin resistance Sprague-Dawley rat are changed. Cardiovasc Drugs Ther. 2008 Dec;22(6):461-8. Epub 2008 Jul 10.
PURPOSE: To observe and compare the effect of taurine on contractions of aortic rings isolated from normal (NC) and insulin resistance (IR) Sprague-Dawley rats, and to explore its underlying mechanism (s). METHODS: The IR animal model was made by feeding rats with high fructose diet for 8 weeks. Aortic rings were isolated and suspended in a tissue bath, and tensions were recorded isometrically. The effects of taurine on provoked contractions of the rings were assessed in absence or presence of different potassium channel or NO-synthase inhibitors. RESULTS: Taurine (20-80 mM) concentration-dependently relaxed precontractions induced by KCl (30 mM) and phenylephrine (1 microM) in NC rings, but enhanced the precontractions in IR rings. Denudation of the endothelium and pretreatment with N (G)-nitro-L-arginine methylester ester (0.1 mM) reversed the contraction enhancement of taurine to relaxation in IR rings. Tetraethylammonium (10 mM) nearly abolished taurine-induced relaxation of NC rings, and augmented taurine-induced contraction enhancement in IR rings. Iberiotoxin (100 nM) only augmented the contraction enhancement in IR rings. 4-Aminopyridine (1 mM), glibenclamide (10 microM) and indomethacin (10 muM) had no influence on the effect of taurine in both NC and IR rings. CONCLUSION: Taurine enhances contractions in IR aortic rings but relaxes the contractions in normal rat aortic ring; the enhancement is endothelium-dependent and the relaxation is endothelium-independent. TEA-sensitive K (+) channel may be involved in these actions; BK (Ca) channel dysfunction and endothelium-derived substances may be related to the contraction enhancement induced by taurine in IR aorta. |
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