Abstract: AIM:To explore the effect and mechanism of endothelin receptor antagonist on local angiotensin system of hypertrophic myocardial tissue.METHODS: Twenty four rats were randomly divided into 3 groups, control group (CG), hypertrophy group (HG) and endothelin receptor antagonist group (EG). The ratios of left ventricle weight to body weight (LVW BW) and left ventricle weight to heart weight (LVW/HW) were measured to reflect myocardial hypertrophy. Protein expression of AT1 R was detected by immunohistochemistry. The concentration of Ang Ⅱ was determined by ria. Activity of ACE was examined by spectrophotometry. A piece of myocardial tissue was observed in light microscope after HE or VG dyeing.RESULTS:(1) In comparison to CG, LVW BW, LVW/HW, ACE activity, the concentration of Ang Ⅱ and the expression of AT₁R of HG were increased significantly (P<0. 05). (2) In EG, ACE activity, the concentration of Ang Ⅱ and the expression of AT₁R were reduced markedly compared with HG (P<0. 05), but ACE activity and the expression of AT₁R were still higher than those in CG (P<0. 05).CONCLUSION:Local angiotensin system is activated in myocardial hypertrophic tissue induced by ne, which leads to hypertrophy of myocardial cell and hyperplasy of collagen. Endothelin-1 probably participates in the activation, which could be inhibited partially by endothelin receptor antagonist, pd142893.

Key words: endothelin, pd142893, angiotensin Ⅱ, angiotensin-convertion enzyme, angiotensin receptor-1