Myocardial Iron Metabolism in the Regulation of Cardiovascular Diseases in Rats

The iron homeostasis plays an important role in cardiac function. To understand how it acts in diabetic and ischemic myocardial injury, we studied the myocardial iron metabolism in diabetic and myocardial ischemic rats. Diabetic rats were induced by intraperitoneal injection of streptozocin (STZ) after intragastric administration of a high-fat diet while the ischemic rat hearts were subjected to coronary artery ligation for 0.5, 1, 6, 12 or 24 h, respectively. In STZ-induced diabetic rats, the contents of serum and myocardial iron were found elevated obviously accompany with the decrease of hepatic iron determined by the flame emission atomic absorption spectroscopy. The levels of superoxide dismutase (SOD), malonaldehyde (MDA) and serum ferritin were increased in diabetic rats. Moreover, protein level of divalent metal transporter 1 (DMT1) was decreased while that for transferrin receptor (TfR) and metal transporter protein 1 (MTP1) was increased. In contrast, no alteration of iron concentration was observed in the ischemic rats. The expression of DMT1, TfR and MTP1 has not changed after infraction. The findings suggested that diabetes mellitus (DM) induced the iron overload in the myocardium, at least in part by up-regulation of TfR. Meanwhile, down-regulation of DMT1 and up-regulation of MTP1 were induced to alleviate the excessive iron in the myocardium. However, myocardial infraction (MI) has not broken the balance of myocardial iron. In conclusion, the iron homeostasis reacts differently in DM and MI.