To study the role of transforming growth factor-betal (TGF-β1) in cardiac hypertrophy and the connection of angietensis Ⅱ (Ang Ⅱ) with it.Cardiac muscle Ang Ⅱ was measured by radioimmunoassay;Subcellar distribution of TGF-β1 in cardiomyocytes was examined by immunohistochemistry after abdominal aorta constriction.The results showed that the levels of AngⅡ、the activities of angiotensin-converting enzyme and ratios of heart weight to body weight were significantly increased after abdominal aorta constriction ( P <0.01).Expression of TGF-β1 in cardiomyocytes cytoplasm increased significantly and reached peak at d7 post-operation;But in nuclei,the expression decreased and disappeared at d14 post-operation ( P <0.01).Trearment with low dose losartan (5mg/kg,selective angiotensin typel receptor antagonist),Carotid blood pressures were not different from coarctation ( P >0.05).Ratios of heart weight to body weight were significantly decreased.The expression of TGF-β1 decreased rapidly in cytoplasm and increased from 23% to 43% in nuclei( P <0.01).We concluded that TGF-β1 involve in the development of cardiac hypertrophy,it possible promote cardiac hypertrophy in cytoplasm and suppress cardiac hypertrophy in nuclei.The role of AngⅡ in the development of cardiac hypertrophy may be mediated by TGF-β1.Losartan can effectively block cardiac hypertrophy.
