Abstract: Objective To investigate the effect of urotensin II on myocardial fibrosis in rats. Methods The pressure overload animal model was established in rats by abdominal aorta coarctation. The rats were divided into sham operation group, modeled for 4, 8 and 12 weeks group. The expression changes of UⅡ, GPR14, col-Ⅰ, col-Ⅲ, and PKA in cardiac tissues were detected by Western blot. Isolated and cultured cardiac myofibroblasts (CFs) from new-born SD rats were treated with UⅡ、KT5720 or SB-611812, and then the proliferation of CFs were observed by microscope and CKK-8. Results The expression of UⅡ,GPR14, col-Ⅰ,col-Ⅲand PKA increased markedly in cardiac tissues of model rat, which were time-dependent. UⅡpromoted the proliferation of CFs (P<0.05), which could be inhibited by KT5720 or SB-611812. Conclusion UⅡ/UT system promoted the occurring and development of myocardial fibrosis.

Key words: urotensin II (UⅡ), myocardial fibrosis, signal transduction, protein kinase A (PKA)