Abstract: AIM To observe the effects of vasonatrin peptide (VNP) on rat abdominal aorta and on ATP-sensitive potassium channels (ATP-sensitive potassium channel, KATP). METHODS Isolated vascular perfusion method was used to determine the effects of VNP on vascular tension and patch clamp was used to observe the effects of VNP on KATP channel. RESULTS VNP evoked concentration-dependent and endothelium-independent relaxations on isolated abdominal aortic artery. Emax of VNP on endothelium intact abdominal aortic artery was (81±8)% and Emax on endothelial denuded abdominal aortic artery was (74±6)%. The relaxations induced by VNP on blood vessels were attenuated by preincubation in organ chambers with glibenclamide (1×10-6 mol/L). VNP enhanced KATP channel currents of abdominal aortic vascular smooth muscle cell. Emax of VNP (1×10-6 M) reinforced KATP channel currents was (112±24)%, and the effects were eliminated by glibenclamide (1×10-6 mol/L). CONCLUSION VNP is an effective vasorelaxing peptide whose action is caused by enhancing currents of ATP-sensitive potassium channel.