Catecholamine toxicity triggers myocardial membrane destabilization in rats: thymol and its counter action

Abstract

We evaluated the protective effects of thymol on myocardial membrane destabilization by isoproterenol (ISO), a synthetic catecholamine which triggers cardiotoxicity in rats. Male albino Wistar rats were pre and co-treated with thymol (7.5 mg kg⁻¹) daily for 7 days. ISO (100 mg kg⁻¹) was injected subcutaneously into rats at an interval of 24 h for two days (6^th and 7^th days) to induce cardiotoxicity. Significantly increased levels/activity of cardiac troponin-T and lactate dehydrogenase (LDH) with increased concentrations of heart thiobarbituric acid reactive substances (TBARS), and decreased concentrations of superoxide dismutase and catalase, were observed in ISO induced cardiotoxic rats. The activity of sodium/potassium-dependent adenosine triphosphatase (Na⁺/K⁺-ATPase) was significantly decreased and the activities of calcium and magnesium-dependent adenosine triphosphatases (Ca²⁺-ATPase and Mg²⁺-ATPase) were significantly increased in the hearts of ISO induced cardiotoxic rats. Furthermore, ISO induced cardiotoxic rats also showed decreased concentrations of potassium (K⁺) and increased concentrations of sodium (Na⁺) and calcium (Ca²⁺) in the heart. Pre and co-treatment with thymol showed near normalized effects on all the biochemical parameters studied. Also, thymol greatly reduced myocardial infarct size. Thus, the present study revealed that thymol prevented the myocardial membrane destabilization in ISO induced cardiotoxic rats due to its strong membrane stabilizing properties.