Abstract: Aim Adrenomelullin is a novel vasodilator with a potent hemodynamic effect on human arterioals.The interaction of adrenomedulling with vasoconstrictors in normal volunteers have not been investigated.Methods 14 normal volunteers were divided into two groups randomly with a double blind manner.Group A (n =7) were treated with ADM or/and norepinephrine and group B(n =7),ADM or/and endothelin,through brachial artery infu-sion of different doses.Forearm blood flow were observed (with plethysmography)before,during and after durg administration.Results Intraarterial infusion of ADM resulted a three-fold increase of forearm blood flow.The vasodilation effect of ADM disappeared 40 minutes after drug discontinuation.Intraarterial infusion of norepinephrine and endothelin resulted 61%and 73%decrease of FBF,respectively.Combined infusion of low dose ADM with high dose norepinephine or endothelin could abolish the vasoconstrictive effects of pre-mentioned vasoconstristors.Conclusion ADM is a potent vasodilator.Its vasodila-tion effect lasts 40 min after discontinuation of infusion.In forearm resistance arteries,ADM can abolish the vasoconstrictive effects of high dose norepinephrine or endothelin.

Key words: adrenomedullin, endothelin, norepinephrine, forearm plethysmography