TGF- β1 of cardiac tissue and ventricular remodeling in rats with acute myocardial infarction / 中国病理生理杂志

ABSTRACT

AIM: To explore the molecular mechanisms about fibrosis and transforming growth factor (TGF) - β1 as well as inflammation in rats heart after acute myocardial infarction (AMI). METHODS: AMI model in rats was produced by left coronary artery ligation. Samples of rat cardiac tissue were collected at the end of 1 week, 4 weeks and 8 weeks. Hemodynamics had been performed before rats were sacrificed. Reverse transcription polymerase chain reaction (RT- PCR) and immunohistochemical methods were used to analyze mRNA expression and protein production of TGF- β1, respectively. Hydroxyproline was determined by chloramines T method. HE staining was resorted to analyze pathological myocardium after AMI. RESULTS: There were remarkable differences in hemodynamics between AMI groups and sham group (P＜0.01). Compared with sham group, TGF-β1mRNA expression and protein production and hydroxyproline quantification were enhanced greatly. Among them, the levels of TGF -β1 and hydroxyproline at 1 week were higher than those at 4 weeks or 8 weeks. A positive correlation between TGF- β1 protein and hydroxyproline was presented (r=0.75 - 0.99, P＜0.05). In microscope, leucocytes infiltrated significantly in the infarcted and border myocardium at 1 week after AMI, and were rarely seen at 4 weeks and 8 weeks. TGF - β1 protein were detected in cytoplasm of cardiac myocyte and leucocytes at 1 week, and at 4 and 8 weeks in myofibroblast and interstitial. CONCLUSIONS:TGF- β1 is upregulated and found in cytoplasm of cardiac myocyte and leucocytes as well as myofibroblast in heart after AMI,which is associated with dynamic changes of hydroxyproline content and inflammation. TGF - β1 is showed to play an important role in myocardial inflammatory repair and ventricular remodeling after AMI.