Effects of Ang Ⅱ on the production of ET-1, NO from adult rat myocardial fibroblasts

AIM: To investigate the effects of Ang Ⅱon the production of ET-1, NO from myocardial fibroblasts (MFs) of adult rat. METHODS: MFs were extracted by enzymatic digestion and anchorage velocity-dependent separation method. In this study, the changes of ET-1 and NO production from MFs in the second passage were examined by radioimmunoassay and by nitrate reductase-dependent assay, separatively. RESULTS: In a specific concentration range, AngⅡ increased ET-1 synthesis in MFs in a concentration-dependent manner. Losartan, the antagonist of angiotensin Ⅱ 1 type recepters (AT₁R), blocked the above effects. Ang Ⅱ may inhibit NO synthesis in MFs. When MFs were treated with losartan+Ang Ⅱ, the production of NO increased significantly, and was higher than that treated with the others (P<0.01). CONCLUSION: Ang Ⅱ may increase the production of ET-1 in MFs via AT₁R and affect NO production in MFs mainly via AT₁R to change the ratio of ET-1 and NO. Ang Ⅱ maybe exert inductive effects on myocardial hypertrophy and heart failure by affecting these complicated balances between bioactive factors produced from MFs.