Evaluation of modulatory effects of taurine in the aortic and myocardial tissue of nitroglycerin-induced tolerance Wistar rats.

Purpose: Important underlying mechanisms of nitroglycerine tolerance development include oxidative stress and endothelial dysfunction, and there is paucity of information on how to reduce the tolerance during long-term administration. Taurine, a sulfonic amino acid, was reported to possess antioxidant, cardio-regulatory, neuro-modulatory, and membrane-stabilizing effect. The present study was designed to investigate the potential ability of taurine to prevent nitroglycerine-induced tolerance. Methods: The effect of taurine on nitroglycerin-induced tolerance was investigated in endothelium intact and endothelium-denuded aortic ring preparations. In the in vivo study, male Wistar rats were pre-treated with taurine for ten days and co-treated with nitroglycerin (GTN) 50 mg/kg for 3 days. Then, the aortic ring was harvested and tested in vitro for GTN tolerance. The serum was used to test for oxidative stress parameter (malondialdehyde, reduced glutathione (GSH), catalase (CAT)). Results: Taurine (20 mM) co-incubated with GTN significantly augmented vasodilatory response to nitroglycerin (GTN) in endothelial-denuded aortic rings. Pre-treatment with taurine (100 and 200 mg/kg) also ameliorated GTN (50 mg/kg)-induced tolerance in isolated aortic ring in rats. Also, taurine (100 and 200 mg/kg) significantly (p < 0.05) increased serum nitrite, GSH, and CAT levels while reducing malondialdehyde (MDA) concentration. Conclusion: Taurine could prevent nitroglycerin-induced tolerance by increasing serum nitric oxide level and decreasing oxidative stress. [ABSTRACT FROM AUTHOR]