title: Vasodilatory effects of homologous adrenomedullin 2 and adrenomedullin 5 on isolated blood vessels of two species of eel.
abstract: In mammals, adrenomedullin (AM) is a potent vasodilator through signalling pathways that involve the endothelium. In teleost fishes, a family of five AMs are present (AM1/4, AM2/3 and AM5) with four homologous AMs (AM1, AM2/3 and AM5) recently cloned from the Japanese eel, Anguilla japonica. Both AM2 and AM5 have been shown to be strong in vivo vasodepressors in eel, but the mechanism of action of homologous AMs on isolated blood vessels has not been examined in teleost fish. In this study, both eel AM2 and AM5 caused a marked vasodilation of the dorsal aorta. However, only AM5 consistently dilated the small gonadal artery in contrast to AM2 that had no effect in most preparations. Neither AM2 nor AM5 had any effect when applied to the first afferent branchial artery; in contrast, eel ANP always caused a large vasodilation of the branchial artery. In the dorsal aorta, indomethacin significantly reduced the AM2 vasodilation, but had no effect on the AM5 vasodilation. In contrast, removal of the endothelium significantly enhanced the AM5 vasodilation only. In the gonadal artery, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ) significantly reduced the AM5 vasodilation suggesting a role for soluble guanylyl cyclase in the dilation, but l-NNA and removal of the endothelium had no effect. The results of this study indicate that AM2 and AM5 have distinct vasodilatory effects that may be due to the peptides signalling via different receptors to regulate vascular tone in eel.
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia. Electronic address: msca@deakin.edu.au.
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Cameron
authors.affiliation: Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba 277-8564, Japan.
authors.forename: Shigenori
authors.initials: S
authors.lastname: Nobata
authors.affiliation: Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Chiba 277-8564, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takei
authors.affiliation: School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3216, Australia.
authors.forename: John A
authors.initials: JA
authors.lastname: Donald
mesh_terms: D053607:Adrenomedullin / Q000737:chemistry / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000811:Anguilla / Q000502:physiology*; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000502:physiology; D009320:Atrial Natriuretic Factor / Q000737:chemistry / Q000378:metabolism; D001808:Blood Vessels / Q000187:drug effects / Q000502:physiology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D008969:Molecular Sequence Data; D009213:Myography; D017386:Sequence Homology, Amino Acid; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D053607:Adrenomedullin; D009320:Atrial Natriuretic Factor
keywords: Adrenomedullin; Anguilla; Endothelium; Nitric oxide; Teleost; Vasodilation