Evaluation of Modulatory Effects of Taurine in the Aortic and Myocardial Tissue of Nitroglycerin-Induced Tolerance Wistar Rats

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. 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)). 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. Taurine could prevent nitroglycerin-induced tolerance by increasing serum nitric oxide level and decreasing oxidative stress.