Cardioprotective effects of losartan and diminazene against the ischemia/reperfusion injury in hyperthyroidism rats

Hyperthyroidism is a condition where the thyroid gland produces high levels of thyroid hormone. Heart diseases are one of the main complications of hyperthyroidism. Several studies have shown that losartan (LOS) and diminazene aceturate (DIZE) possess cardioprotection effects against cardiac hypertrophy, ischemic heart disease, and heart failure. The research aimed to investigate the cardioprotection of LOS, DIZE, and their combination in the case of levothyroxine (LT4)-induced cardiomyopathy in rats. Hyperthyroidism was induced by LT4 in drinking water (12 mg/L) for 28 days. LOS (10 mg/kg, orally) and/or DIZE (15 mg/kg, subcutaneously) were administrated in rats with hyperthyroidism for 28 days. Decreased serum creatine kinase myoglobin and lactate dehydrogenase levels and cardiac hypertrophy by DIZE and combination therapy in hyperthyroidism rats have been reported. Cardiac hemodynamic findings showed that DIZE and its combination with LOS decreased the LT4-mediated left ventricular developed pressure (LVDP), rate pressure product (RPP), and RPP recovery percentage. Elevated cardiac oxidative stress and inflammation were confirmed by decreasing cardiac superoxide dismutase (SOD) activity and increasing the total oxidative stress and tumor necrosis factor-alpha (TNF-α) levels. SOD activity and TNF-α level were reversed by LOS and DIZE administration, respectively. Generally, DIZE and combination therapy with LOS improved cardiac dysfunction caused by hyperthyroidism in rats, whereas LOS alone has not been able to effectively respond to this dysfunction.