【Abstract】Objective To investigate the vasodilation effect of luteolin (Lut) on isolated rat thoracic aorta with endothelium denuded (DRTA) vascular rings and whether its mechanism is related to Kv7 channel. Methods The tension of the DRTA vascular rings was measured with an ex vivo tissue perfusion muscle tone detection system. The DRTA vascular rings were pre-contracted with 60 mM KCl or 0.3 uM U46619, and the effect of luteolin on vascular ring relaxation was observed at 1, 3, 10, 30, 100 and 300 uM. And the effect of 4-AP, XE-991 and ML213 on vasodilation of luteolin was observed. The expression of KCNQ1-KCNQ5 in thoracic aorta was detected by Real-time fluorescence quantitative PCR, and the effect of luteolin on the expression of KCNQ1-KCNQ5 was observed. Western blot was used to detect the expression of Kv7.1 and Kv7.4 proteins inDRTA . Results The maximum vasodilation rates of luteolin on 60 mM KCl and 0.3 uM U46619 pre-contracted in DRTAwere (97.67 ± 8.51)% and (98.42 ± 9.76)%, respectively. And the vasodilation effect showed concentration-dependent characteristics (P<0.05). 4-AP (3 mM) could significantly decline the vasodilation effect of luteolin on DRTA vascular rings at 10 uM, 30 uM and 100 uM (P<0.05). And XE-991 (3 uM) could significantly decline the vasodilation effect of luteolin on DRTA vascularrings at 30 uM and 100 uM (P<0.05). ML213 (1uM) can significantly enhance the vasodilation effect of luteolin on DRTA vascular rings at 3 uM, 10 uM, and 30 uM (P<0.05). In the normalDRTA , The gene expression levels of each subtype of Kv7 channel from high to low were KCNQ1 > KCNQ5 > KCNQ4 > KCNQ3 > KCNQ2. KCNQ1 was the most expressed. Luteolin significantly enhanced the expression of KCNQ1 at 3, 10, 30, 100 uM, and increased the expression of KCNQ2 at 1, 3, 10, 30, 100 uM (P<0.05), and enhanced the expression of KCNQ3 at 3, 10, 30, 100 uM, and enhanced the expression KCNQ4 at 10, 30, 100 uM (P<0.05), however, luteolin did not significantly enhance the expression of KCNQ5 at 1, 3, 10, 30, 100 uM (P>0.05). Luteolin significantly increased the expression of Kv7.1 protein at 3, 10, 30, 100 uM (P<0.05), and significantly increased the expression of Kv7.4 protein at 10, 30, 100 uM in DRTA (P<0.05). Conclusion Luteolin can dilateDRTA vascular rings, which can be attenuated by Kv7 nihibitors. And luteolin can promote the expression of Kv7.1 and Kv7.4 proteins. It is suggested that the vasodilation effect of luteolin may be related to the enhancement of Kv7.1 and Kv7.4 protein expression. This effect makes luteolin a potential therapeutic agent for the prevention and improvement of vascular myogenic response disorder or vasospasm of the thoracic aorta.