Aim To investigate the effect and signal transduction pathway of UrotensinⅡ (UⅡ) on endothelin-1 (ET-1) production in cultured aortic tissues of rat. Methods Aortic slices were incubated with different concentration of UⅡ(10-10～10-7 mol/L) for 3 or 6 h. ET-1 both in medium and tissues were measured with radioimmunoassay. Different inhibitors were added to the medium to study the role of different signal transduction pathways in the stimulating effect of UⅡon production of ET-1. Results The study showed that UⅡ significantly stimulated ET-1 secretion (ET-1 in medium) and production (ET-1 both in medium and tissues) from rat aortic tissues, in a time and concentration dependent manner. After incubation for 3 h, ET-1 secretion and production were increased by 146% and 87.9% respectively in 10-8mol/L of UⅡ group than the control group. After incubation for 6h, ET-1 secretion was increased by 59.2%, 108%, 159.6% and 178.0% in UⅡ (10-10, 10-9, 10-8, 10-7 mol/L) group respectively. And ET-1 production was increased by 40.6%, 68.4%, 103.1% and 105.7% in 10-10～10-7 mol/L of UⅡ group respectively. Furthermore, the effect of UⅡ (10-8 mol/L) were inhibited by 34.1%, 24.5%, 32.2%, 32.1% and 27.6% (p<0.01) in secretion and by 33.5%, 31.5%, 25.8%, 28.0% and 36.8% (p<0.01) in production when incubated with nicardipine, H7, PD98059, actinomycin D and cyclophosphamide respectively, which are inhibitors of calcium channel, PKC, MAPK, mRNA production and protein synthesis respectively. Conclusion UⅡ could stimulate ET-1 synthesis and secretion in rat aortic tissues, and this effect might be mediated by Ca²⁺, PKC, and MAPK signal transduction pathway. It was also proposed that UⅡ might play vasoconstrictive actions partly through ET-1 production.