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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: 4-Aminopyridine, Acetylcholine, Administration, Oral, Animals, Aorta, Blood Glucose, Blood Pressure, Cyclooxygenase Inhibitors, Disease Models, Animal, Dose-Response Relationship, Drug, Drug Synergism, Endothelium, Vascular, Endothelium-Dependent Relaxing Factors, Fructose, Glyburide, In Vitro Techniques, Indomethacin, Insulin, Insulin Resistance, Male, NG-Nitroarginine Methyl Ester, Nitric Oxide, Nitric Oxide Donors, Nitroprusside, Peptides, Phenylephrine, Potassium Channel Blockers, Potassium Chloride, Rats, Rats, Sprague-Dawley, Taurine, Tetraethylammonium, Vasoconstriction, Vasodilation.
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Are effects of taurine on aortic rings isolated from fructose-fed insulin resistance Sprague-Dawley rat changed? Context: 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). 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. 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.
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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. Final Decision: yes