title: Functional receptors for fish neuropeptide urotensin II in major rat arteries.
abstract: Receptor binding of fish neuropeptide urotensin II (UII) was characterized in membranes isolated from major rat arteries. Monoiodinated UII radioligand (125I-UII) was prepared and purified using high-pressure liquid chromatography (HPLC). The contractile potency of iodinated UII (I-UII) on rat thoracic aorta strips was somewhat lower than that of native UII. The binding of 125I-UII to the membrane preparations of rat thoracic aorta was saturable, specific and time-dependent. Scatchard analysis indicated a single population of binding sites with an apparent dissociation constant of 5.9 x 10(-9) M. The calculated maximal number of binding sites was about 155 fmol/mg protein. The specific binding to the membrane preparations from the abdominal aorta and mesenteric artery was about 27 and 8%, respectively, of those in the thoracic aorta, which corresponds to the order of contractile potency of UII on rat blood vessels: thoracic aorta greater than abdominal aorta greater than mesenteric artery. The displacement of 125I-UII binding by the UII peptide or its fragments (UII-(5-12), UII-(6-12) and UII-(6-11] were also comparable to their contractile effects on rat thoracic aorta strips (UII greater than UII-(5-12) greater than UII-(6-12) much greater than UII-(6-11]. These results suggest that the fish neuropeptide, UII, can induce contraction of rat vascular tissue by interacting with its functional receptors.
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Medicine, University of Calgary, Alberta, Canada.
authors.forename: H
authors.initials: H
authors.lastname: Itoh
authors.forename: D
authors.initials: D
authors.lastname: McMaster
authors.forename: K
authors.initials: K
authors.lastname: Lederis
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001158:Arteries / Q000378:metabolism; D001665:Binding Sites; D005399:Fishes / Q000378:metabolism*; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014579:Urotensins / Q000378:metabolism*
chemical_list: D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D010455:Peptides; D014579:Urotensins; C029677:urotensin II