Abstract: 【Abstract】 Objective To investigate the effects of different doses of Tetramethylpyrazine (TMP) on collagen synthesis and Nogo expression in cardiac fibroblasts and the potential role of Nogo in myocardial fibrosis. Methods The cultured neonatal rat cardiac fibroblasts were induced by angiotensin Ⅱ and TMP at the same time. The mRNA expression of Nogo-A, Nogo-B and collagen Ⅰ were detected with real-time fluorescence quantitative PCR. And Nogo protein was semi-quantitatively detected by using Western blot method. Results Under the intervention of TMP, the increased mRNA expression of Nogo-A and collagen Ⅰ induced by angiotensin Ⅱ were decreased, while the decreased mRNA expression of Nogo-B was increased. Compared with the control group, the expression of Nogo-A protein and Nogo-B protein showed similar changes as evaluated with Western blot. Conlusion TMP could inhibit collagen synthesis in cardiac fibroblast induced by angiotensin Ⅱ. The accompanying differential expression of Nogo-A and Nogo-B indicated that the anti-fibrosis effect of TMP might be related to the regulation effects of Nogo gene.